Young Ji International School / College
Page 1
Chapter 1
The Nature of Science
What is science? What is technology? You know that science and technology are fields of study which are full of wonders and amazing discoveries. Today‘s world is an environment equipped with sophisticated machineries, which are brought about by the impact of science and technology. Term
Definition
Biology Biotechnology Concoction Curiosity Creativity Intellectual honesty
-
Open-mindedness Rationality Technology -
is the study of living things. refers to all developed technologies related to living things. refers to the boiled water with accompanying herbal leaves to cure some diseases. is the strong desire to understand events/phenomena. is the ability to find answer to a problem using unusual or uncommon method. refers to not claiming the works of others as one‘s own. not jumping to conclusions. is a belief in cause and effect. is an application of science principles to practical use.
Impact of Science and Technology in Daily Life
For sure the words ―science‖ and ―technology‖ have an impact in your life. You know very well that science refers to a highly organized and systematic body of knowledge from which all other concepts or ideas come from. The study of general science doesn‘t just add to our understanding of our natural surroundings; it allows us to make discoveries that help us. Technology is the use of scientific discoveries. Technology has produced such diverse and important things as television, artificial hearts, jets, computers, calculators, telephones and satellites name just few.
Yet, knowledge alone, if not applied, is practically useless. For example, we learn to appreciate the usefulness of wheels when these are attached to cabinets, TV racks and refrigerators, and moving these appliances becomes easy.
Science, technology and society (STS), also referred to as science and technology studies, is the study of how social, political, and cultural values affect scientific research and technological innovation, and how these, in turn, affect society, politics and culture. STS scholars are Young Ji International School / College
Page 2
interested in a variety of problems including the relationships between scientific and technological innovations and society, and the directions and risks of science and technology. More than two dozen universities worldwide offer bachelor's degrees in STS. About half of these also offer doctoral or master's degrees. An STS model has been developed by scholars to consider the internal and external effects. The field of STS is related to history and philosophy of science although with a much broader emphasis on social aspects of science and technology.
Early developments The key disciplinary components of STS took shape independently, beginning in the 1960s, and developed in isolation from each other well into the 1980s, although Ludwik Fleck's monograph (1935) Genesis and Development of a Scientific Fact anticipated many of STS's key themes: Science studies, a branch of the sociology of scientific knowledge that places scientific controversies in their social context. History of technology, that examines technology in its social and historical context. Starting in the 1960s, some historians questioned technological determinism, a doctrine that can induce public passivity to technologic and scientific 'natural' development. At the same time, some historians began to develop similarly contextual approaches to the history of medicine. History and philosophy of science (1960s). After the publication of Thomas Kuhn's well-known The Structure of Scientific Revolutions (1962), which attributed changes in scientific theories to changes in underlying intellectual paradigms, programs were founded at the University of California, Berkeley and elsewhere that brought historians of science and philosophers together in unified programs.
Science, technology, and society In the mid- to late-1960s, student and faculty social movements in the U.S., UK, and European universities helped to launch a range of new interdisciplinary fields (such as women's studies) that were seen to address relevant topics that the traditional curriculum ignored. One such development was the rise of "science, technology, and society" programs, which are also—confusingly—known by the STS acronym. Drawn from a variety of disciplines, including anthropology, history, political science, and sociology, scholars in these programs created undergraduate curricula devoted to exploring the issues raised by science and technology. Unlike scholars in science studies, history of technology, or the history and philosophy of science, they were and are more likely to see themselves as activists working for change rather than dispassionate, "ivory tower" researchers. As an example of the activist impulse, feminist scholars in this
Young Ji International School / College
Page 3
and other emerging STS areas addressed themselves to the exclusion of women from science and engineering. Science, engineering, and public policy studies emerged in the 1970s from the same concerns that motivated the founders of the science, technology, and society movement: A sense that science and technology were developing in ways that were increasingly at odds with the public's best interests. The science, technology, and society movement tried to humanize those who would make tomorrow's science and technology, but this discipline took a different approach: It would train students with the professional skills needed to become players in science and technology policy. Some programs came to emphasize quantitative methodologies, and most of these were eventually absorbed into systems engineering. Others emphasized sociological and qualitative approaches, and found that their closest kin could be found among scholars in science, technology, and society departments. Earth Science Earth science or Geoscience is an all-embracing term referring to the fields of science dealing with planet Earth. It is arguably a special branch of planetary science, though with a much older history. There are both reductionist and holistic approaches to Earth sciences. The formal discipline of Earth sciences may include the study of the atmosphere, hydrosphere, oceans and biosphere, as well as the solid earth. Typically, Earth scientists will use tools from physics, chemistry, biology, chronology, and mathematics to build a quantitative understanding of how the Earth system works, and how it evolved to its current state. Just as general science can be divided into four general areas of earth science, Chemistry, Physics, and Biology and earth science Geology is the study of Earth, its matter and the processes that form and change earth. Some of the things you‘ll look at are volcanoes, earthquakes, maps fossils, mountains and land use. Geologist search for oil, study volcanoes, identify rocks and minerals, study fossils and glaciers and determine how mountains form.
Meteorology is the study of weather and the forces and processes that cause it. You‘ll learn about storm patterns, climates and what factors cause our daily weather. A meteorologist is a scientist who studies weather patterns in order to predict daily weather.
Young Ji International School / College
Page 4
Astronomy is the study of objects in space, including stars, planets and comets. Before telescopes were invented, this branch of earth science mainly dealt with descriptions of the positions of the stars and planets. Today, scientists who study space objects seek evidence about the beginning of the universe. The study of astronomy help scientists understands Earth‘s origin. Oceanography is the study of Earth‘s oceans. Scientists who study the oceans conduct research on the physical and chemical properties of ocean water. Oceanographers also study the processes that occur within oceans and the effects humans have on these processes.
The Effects of Technology Not all of the changes created by technology are good. Advances in medical technology have extended the time people live. But sometimes the quality of life for these people is very low. For example, people can be kept alive by machines, even though they are permanently unconscious- in a coma. Technology has also led to the development of modern machines, such as cars. Cars allow us to mobile and travel freely, but they also create pollution and contribute to congestion in cities. Another machine, the air conditioner, provides cool comfort but uses electricity; and the Freon chemical released during its use harms the environment. Concept Review 1. List ways technology helps you. 2. What problems can technology cause?
Solving Problems To solve any problem, you need to have a strategy.
Identifying the problem is the first step of any strategy.
Next, you need to collect information about the problem. You need to know the basic facts of when soccer practice begins and ends how much homework you have, what chores need to be done, and when the TV set be put on.
After you have determined these things, you might try writing out a time schedule.
Young Ji International School / College
Page 5
First write in the activities that have fixed times. Then, fill in each the other activities. You may have to try different arrangements before you find the solution that you think is the best. In solving this problem, making is list helped you organize the parts of your problem. There are other ways to solve problems. You might try the strategy of eliminating possibilities. You could do this by trying options until you find the one that works. This method is also known as trial and error. Sometimes it is easier to solve a problem by finding out what does not work. Another strategy is to solve a simpler, related problem, or to make a model, drawing or graph to help you visualize the problem, if your first strategy does not work, keep trying different strategies.
Lava flows from the Kīlauea volcano into the ocean on the Island of Hawaii The following fields of science are generally categorized within the Earth sciences: Geology describes the rocky parts of the Earth's crust (or lithosphere) and its historic development. Major sub disciplines are mineralogy and petrology, geochemistry, geomorphology, paleontology, st ratigraphy, structural geology, engineering geology, and sediment logy.
Physical geography covers aspects of geomorphology, soil study, hydrology, meteorology, climatology, and biogeography.
Geophysics and geodesy investigate the shape of the Earth, its reaction to forces and its magnetic and gravity fields. Geophysicists explore the Earth's core and mantle as well as the tectonic and seismic activity of the lithosphere. Geophysics is commonly used to supplement the work of geologists in developing a comprehensive understanding of crustal geology, particularly in mineral and petroleum exploration. See Geophysical survey.
Soil science covers the outermost layer of the Earth's crust that is subject to soil formation processes (or pedosphere). Major sub disciplines include edaphology and pedology.
Young Ji International School / College
Page 6
Ecology covers the interactions between the biota, with their natural environment. This field of study differentiates the study of the Earth, from the study of other planets in our Solar System; the Earth being the only planet teeming with life.
Hydrology (includes oceanography and limnology) describe the marine and freshwater domains of the watery parts of the Earth (or hydrosphere). Major subdisciplines include hydrogeology and physical, chemical, [citation needed] and biological oceanography. Glaciology covers the icy parts of the Earth (or cryosphere).
Atmospheric sciences cover the gaseous parts of the Earth (or atmosphere) between the surface and the exosphere (about 1000 km). Major subdisciplines include meteorology, climatology, atmospheric chemistry, and atmospheric physics.
Using Scientific Method Scientist uses a series of planned steps, called scientific method, to solve problems. The basic scientific methods are the following:
1. 2. 3. 4. 5.
Commonly used Scientific methods Determine the problem Make a hypothesis Test your hypothesis Analyze the results Draw conclusions A hypothesis is a testable prediction of a problem. A variable is a changeable factor in an experiment. A control is a standard for comparison.
Theories and Laws Many things we learn about in science, such as how animals evolve or how continents move, are called theories. Scientists are constantly testing hypotheses. When new data gathered over a long period of time support a hypothesis, scientists become convinced that the hypotheses is correct. They can sue such hypotheses to form theories. An explanation backed by results obtained from repeated test or experiments is a theory. A scientific law is a ―rule of nature‖ that describes the behavior of something in nature. Generally, laws predict or describe what will happen in a given situation, but don‘t explain why.
Young Ji International School / College
Page 7
An example of the law is Newton‘s fists law of motion. It states that an object continues in motion, or at rest, until its acted upon by an outside force. Concept Review 1. What are some strategies you can use to solve the problems/ 2. Apply: Imagine that your bike chain came off after riding over a stick, and you think the stick must have been the cause. Is that a hypotheses or a theory. Measurement and Safety Measurement is the assignment of numbers to objects or events. It is a cornerstone of most natural sciences, technology, economics, and quantitative research in other social sciences. Any measurement of an object can be judged by the following metameasurement criteria values: level of measurement (which includes magnitude), dimensions (units), and uncertainty. They enable comparisons to be done between different measurements and reduce confusion. Even in cases of clear qualitative similarity or difference, increased precision through quantitative measurement is often preferred in order to aid in replication. For example, different colors may be operationalized based either on wavelengths of light or (qualitative) terms such as "green" and "blue" which are often interpreted differently by different people. The science of measurement is called metrology.
A typical tape measure with both metric and US units and two US pennies for comparison 
Mass is a property of a physical body which determines the body's resistance to being accelerated by a force and the strength of its mutual gravitational attraction with other bodies. The SI unit of mass is the kilogram (kg).
Mass is not the same thing as weight, even though we commonly calculate an object's mass by measuring its weight. A man standing on the Moon would weigh less than he would on Earth because of the lower gravity, but he would have the same mass (he would have to recalibrate his bathroom scale for lunar gravity). Young Ji International School / College
Page 8
For everyday objects and energies well-described by Newtonian physics, mass describes the amount of matter in an object. However, at very high speeds or for subatomic particles, special relativity shows that energy is an additional source of mass. Thus, any stationary body having mass has an equivalent amount of energy, and all forms of energy resist acceleration by a force and have gravitational attraction. There are several distinct phenomena which can be used to measure mass. Although some theorists have speculated some of these phenomena could be independent of each other, current experiments have found no difference among any of the ways used to measure mass: Inertial mass measures an object's resistance to being accelerated by a force (represented by the relationship F=ma).
Active gravitational mass measures the gravitational force exerted by an object.
Passive gravitational mass measures the gravitational force experienced by an object in a known gravitational field.
Mass-Energy measures the total amount of energy contained within a body, using E=mc²
Weight is a measure of gravitational force.
The standard unit for weight is a Newton, named after Sir Isaac Newton, who was the first person describe gravity. In SI, a can of soup weights 0.4 newtons.
Area, Volume, and Density Some measurements, such as area, volume and density require a combination of SI units.
Area is the amount of surface included within a set of boundaries. Let say you want to know the area of your desk top.
Density is a measure of the amount of matter that occupies a particular space. It‘s determined by dividing the mass of an object by its volume.
Volume is a measure of how much space an object occupies, so if you wanted to know the volume of a solid object, like your book, you‘d need to know its length, width and height. Then, you‘d multiply three measurements to find the volume.
Young Ji International School / College
Page 9
The cubic meter (m3) is the basic unit of volume in SI, but liquid volumes are often measured in liters (L) and milliliters (mL). Density= mass Volume
D= m v
An SI unit that is often used to express density is grams per cubic centimeter (g/cm3). How might you express the density of a liquid? We often use grams per milliliter (g/mL).
Units of mass
The kilogram is one of the seven SI base units; one of three which is defined ad hoc, without reference to another base unit. The standard International System of Units (SI) unit of mass is the kilogram (kg). The kilogram is 1000 grams (g), which were first defined in 1795 as one cubic decimeter of water at the melting point of ice. Then in 1889, the kilogram was redefined as the mass of the international prototype kilogram, and as such is independent of the meter, or the properties of water. As of January 2013, there are several proposals for redefining the kilogram yet again, including a proposal for defining it in terms of the Planck constant. Other units are accepted for use in SI: The tonne (t) (or "metric ton") is equal to 1000 kg.
The electronvolt (eV) is a unit of energy, but because of the mass–energy equivalence it can easily be converted to a unit of mass, and is often used like one. In this context, the mass has units of eV/c2. The electronvolt is common in particle physics.
The atomic mass unit (u) is 1/12 of the mass of a carbon-12 atom, approximately 1.66×10−27 kg. The atomic mass unit is convenient for expressing the masses of atoms and molecules. Young Ji International School / College
Page 10
The weight of an object is usually taken to be the force on the object due to gravity. Its magnitude (a scalar quantity), often denoted by an italic letter W, is the product of the mass m of the object and the magnitude of the local gravitational acceleration g; thus: W = mg. The unit of measurement for weight is that of force, which in the International System of Units (SI) is the Newton. For example, an object with a mass of one kilogram has a weight of about 9.8 Newton‘s on the surface of the Earth, and about one-sixth as much on the Moon. In this sense of weight, a body can be weightless only if it is far away from any gravitating mass.
A spring scale measures the weight of an object. SI unit
newton (N)
Derivations from other quantities
W=m¡g
Area is the quantity that expresses the extent of a two-dimensional figure or shape, or planar lamina, in the plane. Surface area is its analog on the twodimensional surface of a three-dimensional object. Area can be understood as the amount of material with a given thickness that would be necessary to fashion a model of the shape, or the amount of paint necessary to cover the surface with a single coat. It is the two-dimensional analog of the length of a curve (a onedimensional concept) or the volume of a solid (a three-dimensional concept). The area of a shape can be measured by comparing the shape to squares of a fixed size. In the International System of Units (SI), the standard unit of area is the square meter (written as m2), which is the area of a square whose sides are one meter long. A shape with an area of three square meters would have the same area as three such squares. In mathematics, the unit square is defined to have area one, and the area of any other shape or surface is a dimensionless real number. Volume is the quantity of three-dimensional space enclosed by some closed boundary, for example, the space that a substance (solid, liquid, gas, or plasma) or Young Ji International School / College
Page 11
shape occupies or contains. Volume is often quantified numerically using the SI derived unit, the cubic meter. The volume of a container is generally understood to be the capacity of the container, i. e. the amount of fluid (gas or liquid) that the container could hold, rather than the amount of space the container itself displaces. Three dimensional mathematical shapes are also assigned volumes. Volumes of some simple shapes, such as regular, straight-edged, and circular shapes can be easily calculated using arithmetic formulas. Volumes of a complicated shape can be calculated by integral calculus if a formula exists for the shape's boundary. Where a variance in shape and volume occurs, such as those that exist between different human beings, these can be calculated using three-dimensional techniques such as the Body Volume Index. One-dimensional figures (such as lines) and twodimensional shapes (such as squares) are assigned zero volume in the threedimensional space. The density, or more precisely, the volumetric mass density, of a substance is its mass per unit volume. The symbol most often used for density is Ď . Mathematically, density is defined as mass divided by volume:
where Ď is the density, m is the mass, and V is the volume. In some cases (for instance, in the United States oil and gas industry), density is loosely defined as its weight per unit volume, although this is scientifically inaccurate – this quantity is more specifically called specific weight. A temperature is a comparative objective measure of hot and cold. The comparison is through detection of heat radiation, particle velocity, kinetic energy, or most commonly, by the bulk behavior of a thermometric material. It may be calibrated in any of various temperature scales, Celsius, Fahrenheit, Kelvin, etc. Measurements with a small thermometer, or by detection of heat radiation, can show that the temperature of a body of material can vary from time to time and from place to place within it. If changes happen too fast, or with too small a spacing, within a body, it may be impossible to define its temperature. Thus the concept of temperature in general has an empirical content.
Young Ji International School / College
Page 12
Temperature
Temperature is a measure of how hot or cold something is.
As you probably know, temperature is measured with a thermometer. What you probably didn‘t know is that SI unit for temperature is a Kelvin. On the Kelvin scale, absolute zero is 0, the coldest temperature. The symbol for Kelvin is K. instead of using Kelvin thermometers, many scientists use Celsius thermometers. The symbol for a Celsius degree is °C. the Celsius temperature scale is based on the freezing and boiling points of water. Degrees Celsius + 273.16 = Kelvin Making accurate measurements in SI is an important part of nay experiment. If you don‘t make a accurate measurements, your results and conclusions are invalid. Concept Review 1. List the SI units for the following measurement: length, mass, weight, area, volume, density, and temperature. 2. Explain the differences between mass and weight and between area and volume. 3. When should you use safety goggles/ 4. Apply: Why do you suppose you should always slant test tubes away from yourself and others when heating them? Why should tie back long hair and loose clothing?
Young Ji International School / College
Page 13
Understanding Concepts Complete each sentence 1. Finding out how sea lilies feed would be studied in ___________. 2. Soils are studied in the field of ________________. 3. _________ could be used to find how light affects plants. 4. The SI unit of _______ is the Newton. 5. ____________ is a measure of how much space an object occupies.
1. 2. 3. 4.
Think and Write Critically Why would a scientist studying a volcano like. Mount Saint Helens also need some knowledge of physics and chemistry? How have advances in technology been harmful to our planet? How does a theory differ from a hypothesis? How would you determine the volume of a cardboard box given that its area is 100 m2?
Chapter 2
Motion and Forces
Motion is a change in position of an object with respect to time and its reference point. Motion is typically described in terms of displacement, direction, velocity, acceleration, and time. Motion is observed by attaching a frame of reference to a body and measuring its change in position relative to that frame. If the position of a body is not changing with the time with respect to a given frame of reference the body is said to be at rest, motionless, immobile, stationary, or to have constant (time-invariant) position. An object's motion cannot change unless it is acted upon by a force, as described by Newton's first law. Momentum is a quantity which is used for measuring motion of an object. An object's momentum is directly related to the object's mass and velocity, and the total momentum of all objects in an isolated system (one not affected by external forces) does not change with time, as described by the law of conservation of momentum. The study of motion deals with 1. The study of motion of solids (mechanics). 2. study of motion of fluids (fluid mechanics) 
Force is any interaction which tends to change the motion of an object. [1] In other words, a force can cause an object with mass to change its velocity (which includes to begin moving from a state of rest), i.e., to accelerate. Force can also be described by intuitive concepts such as a push or a pull. A force has both magnitude and direction, making it a vector quantity. It is measured in the SI unit of Newton‘s and represented by the symbol F.
Young Ji International School / College
Page 14
The original form of Newton's second law states that the net force acting upon an object is equal to the rate at which its momentum changes with time. If the mass of the object is constant, this law implies that the acceleration of an object is directly proportional to the net force acting on the object, is in the direction of the net force, and is inversely proportional to the mass of the object. As a formula, this is expressed as:
where the arrows imply a vector quantity possessing both magnitude and direction.
Distance, or farness, is a numerical description of how far apart objects are. In physics or everyday usage, distance may refer to a physical length, or estimation based on other criteria (e.g. "two counties over"). In mathematics, a distance function or metric is a generalization of the concept of physical distance. A metric is a function that behaves according to a specific set of rules, and is a concrete way of describing what it means for elements of some space to be "close to" or "far away from" each other. In most cases, "distance from A to B" is interchangeable with "distance between B and A". Time is the fourth dimension and a measure in which events can be ordered from the past through the present into the future, and also the measure of durations of events and the intervals between them. Time has long been a major subject of study in religion, philosophy, and science, but defining it in a manner applicable to all fields without circularity has consistently eluded scholars. Nevertheless, diverse fields such as business, industry, sports, the sciences, and the performing arts all incorporate some notion of time into their respective measuring systems. Some simple, relatively uncontroversial definitions of time include "time is what clocks measure ―and "time is what keeps everything from happening at once".
In everyday use and in kinematics, the speed of an object is the magnitude of its velocity (the rate of change of its position); it is thus a scalar quantity. The average speed of an object in an interval of time is the distance travelled by the object divided by the duration of the interval;[2] the instantaneous speed is the limit of the average speed as the duration of the time interval approaches zero. Like velocity, speed has the dimensions of a length divided by a time; the SI unit of speed is the meter per second, but the most usual unit of speed in everyday usage is the kilometer per hour or, in the US and the UK, miles per hour. For air and marine travel the knot is commonly used.
Direction is the information contained in the relative position of one point with respect to another point without the distance information. Directions may be
Young Ji International School / College
Page 15
either relative to some indicated reference or absolute according to some previously agreed upon frame of reference. Direction is often indicated manually by an extended index finger or written as an arrow. On a vertically oriented sign representing a horizontal plane, such as a road sign, "forward" is usually indicated by an upward arrow. Mathematically, direction may be uniquely specified by a unit vector, or equivalently by the angles made by the most direct path with respect to a specified set of axes.
Distance Time graph
In mathematics, the slope or gradient of a line is a number that describes both the direction and the steepness of the line. Slope is often denoted by the letter m. The direction of a line is increasing, decreasing, horizontal or vertical.
A line is increasing if it goes up from left to right. The slope is positive, i.e. .
A line is decreasing if it goes down from left to right. The slope is negative, i.e. . If a line is horizontal the slope is zero. This is a constant function. If a line is vertical the slope is undefined. The steepness, incline, or grade of a line is measured by the absolute value of the slope. A slope with a greater absolute value indicates a steeper line Young Ji International School / College
Page 16
Concept Review 1. A jogging path is 400 meters long. A jogger travels the entire length in 90nseconds. What is the speed of the jogger/ 2. Can you give the velocity of the jogger in Question 1? Explain your answer. 3. Write one complete sentence for each term listed below. Motion speed distance-time graph Distance velocity slope Average Speed The average speed is the total distance traveled divided by the total time passed. To find the average speed of an object, you do not have to know its actual speeds. You need to know only the time the object took to travel a total distance. For example, the car traveled 90 kilometers in 3 hours. Its average speed was:\ Average speed = total distance time
= 90 km 3h
= 30 km/hr
Finding acceleration
Young Ji International School / College
Page 17
Acceleration is the rate at which the velocity of an object changes over time. An object's acceleration is the net result of any and all forces acting on the object, as described by Newton's Second Law. The SI unit for acceleration is the meter per second squared (m/s2). Accelerations are vector quantities (they have magnitude and direction) and add according to the parallelogram law. As a vector, the calculated net force is equal to the product of the object's mass (a scalar quantity) and the acceleration. For example, when a car starts from a standstill (zero relative velocity) and travels in a straight line at increasing speeds, it is accelerating in the direction of travel. If the car turns there is acceleration toward the new direction. For this example, we can call the accelerating of the car forward a "linear acceleration", which passengers in the car might experience as force pushing them back into their seats. When changing directions, we might call this "nonlinear acceleration", which passengers might experience as a sideways force. If the speed of the car decreases, this is acceleration in the opposite direction of the direction of the vehicle, sometimes called deceleration. Passengers may experience deceleration as a force lifting them away from their seats. Mathematically, there is no separate formula for deceleration, as both are changes in velocity. Each of these accelerations (linear, non-linear, deceleration) might be felt by passengers until their velocity and direction match that of the car. For example, find the acceleration of a swimmer who changes speed in the last 3 seconds of a race. The speed increased from 2 m/s to 8 m/s. the acceleration is acceleration = final speed – original speed time = 8 m/s -2 m/s 3s = 6 m/s 3s = 2 m/s2 The acceleration is 2 m/s per second. However, the swimmer‘s speed may not have increase by exactly 2 m/s each second. It may have increased more in one second. Slowing Down Acceleration can also mean a decrease in speed. Young Ji International School / College
Page 18
The kind of acceleration in which speed decreases is called deceleration. You can find the deceleration of an object the same way you find acceleration. For example, suppose a runner traveling at 4 m/s comes to a stop in 2 seconds. What is the deceleration? deceleration = final speed – original speed time = 0 m/s - 4 m/s 2s = - 4 m/s 2s = -2 m/s2
Concept Review 1. What is the average speed of a race car that travels 60 meters in 20 seconds/ 2. What is the acceleration of a plane that increases its speed from 800 km/hr in 5 seconds? 3. Richard was swimming at a speed of 3 m/s when she started to slow down. She slowed to a stop in 2 seconds. What was her acceleration? What is this kind of acceleration called? 4. Write one complete sentence for each term listed below. Average speed deceleration acceleration
Push and Pull A push or a pull can change the motion of an object. A push or a pull is an example of a force.  A force is any cause of a change in motion. Forces change the speed and direction of an object. In short, forces cause acceleration. When you punch a volley-ball or pull a bowstring, you are applying a muscular force.
Young Ji International School / College
Page 19
A muscular force comes from the expanding and contracting of muscle tissue. When it is released, the bowstring applies an elastic force to the arrow.
An elastic force is produced by any bent or stretched object that returns to its original shape.
A push–pull system in business describes the movement of a product or information between two subjects. On markets the consumers usually "pull" the goods or information they demand for their needs, while the offers or suppliers "push" them toward the consumers. In logistics chains or supply chains the stages are operating normally both in push- and pull-manner. Push production is based on forecast demand and pull production is based on actual or consumed demand. The interface between these stages is called the push–pull boundary or decoupling point.
Example of push and full Force You need to apply a muscular force to shove a crate across a floor. At the same time, another force is also acting on the crate. That force is friction. Friction opposes the motion of one surface past another. A Pull to Earth Friction acts on a ball that is tossed up into the air. The ball rubs against gases in the air. The rubbing slows and stops the ball. Another force is also stopping the ball. The force, gravity, pulls the ball to the ground. Gravity is a force of attraction between two objects.
Muscular force
Young Ji International School / College
Page 20
Elasticity is the tendency of solid materials to return to their original shape after being deformed. Solid objects will deform when forces are applied on them. If the material is elastic, the object will return to its initial shape and size when these forces are removed. Perfect elasticity is an approximation of the real world, and few materials remain purely elastic even after very small deformations. In engineering, the amount of elasticity of a material is determined by two types of material parameter. The first type of material parameter is called a modulus, which measures the amount of force per unit area (stress) needed to achieve a given amount of deformation. The units of modulus are Pascal’s (Pa) or pounds of force per square inch (psi, also lbf/in2). A higher modulus typically indicates that the material is harder to deform. The second type of parameter measures the elastic limit. The limit can be a stress beyond which the material no longer behaves elastic and deformation of the material will take place. If the stress is released, the material will elastically return to a permanent deformed shape instead of the original shape. Friction Friction is the force resisting the relative motion of solid surfaces, fluid layers, and material elements sliding against each other. There are several types of friction: Dry friction resists relative lateral motion of two solid surfaces in contact. Dry friction is subdivided into static friction ("stiction") between non-moving surfaces, and kinetic friction between moving surfaces. Fluid friction describes the friction between layers of a viscous fluid that are moving relative to each other. Lubricated friction is a case of fluid friction where a lubricant fluid separates two solid surfaces. Skin friction is a component of drag, the force resisting the motion of a fluid across the surface of a body. Internal friction is the force resisting motion between the elements making up a solid material while it undergoes deformation. Gravity Gravitation or gravity is a natural phenomenon by which all physical bodies attract each other. Gravity gives weight to physical objects and causes them to fall toward the ground when dropped. Gravitation is most accurately described by the general theory of relativity (proposed by Einstein) which describes gravitation as a consequence of the curvature of space-time. For most situations gravity is well approximated by Newton's law of universal gravitation, which postulates that the gravitational force of two bodies of mass is directly proportional to the product of their masses and inversely proportional to the square of the distance between them. In pursuit of a theory of everything, the merging of general relativity and quantum mechanics (or quantum field theory) into a more general theory Young Ji International School / College
Page 21
of quantum gravity has become an area of active research. It is hypothesized that the gravitational force is mediated by a massless spin-2 particle called the graviton, and that gravity would have separated from the electronuclear force during the grand unification epoch.  The First Law of Motion Newton's laws of motion are three physical laws that together laid the foundation for classical mechanics. They describe the relationship between a body and the forces acting upon it, and its motion in response to said forces. They have been expressed in several different ways over nearly three centuries, and can be summarized as follows:  First law: When viewed in an inertial reference frame, an object either remains at rest or continues to move at a constant velocity, unless acted upon by an external force. The First Law of Motion states: 1. An object at rest remains at rest unless acted upon by an unbalanced force. 2. An object in motion continues to move at a constant speed and in a straight line unless acted upon by an unbalanced force.
Newton's first law The first law states that if the net force (the vector sum of all forces acting on an object) is zero, then the velocity of the object is constant. Velocity is a vector quantity which expresses both the object's speed and the direction of its motion; therefore, the statement that the object's velocity is constant is a statement that both its speed and the direction of its motion are constant.  The first law can be stated mathematically as
Consequently, An object that is at rest will stay at rest unless an external force acts upon it. An object that is in motion will not change its velocity unless an external force acts upon it. This is known as uniform motion. An object continues to do whatever it happens to be doing unless a force is exerted upon it. If it is at rest, it continues in a state of rest (demonstrated when a tablecloth is skillfully whipped from under dishes on a tabletop and the dishes remain in their initial state of rest). If an object is moving, it continues to move without turning or changing its speed. This is evident in space probes that continually move in outer space. Changes in motion must be imposed against the tendency of an object to retain its state of motion. In the Young Ji International School / College
Page 22
absence of net forces, a moving object tends to move along a straight line path indefinitely. Newton placed the first law of motion to establish frames of reference for which the other laws are applicable. The first law of motion postulates the existence of at least one frame of reference called a Newtonian or inertial reference frame, relative to which the motion of a particle not subject to forces is a straight line at a constant speed. Newton's first law is often referred to as the law of inertia. Thus, a condition necessary for the uniform motion of a particle relative to an inertial reference frame is that the total net force acting on it is zero. Concept Review 1. Give an example of each of these forces acting on an object: muscular, elastic, frictional, and gravity. 2. How can an unbalanced force change the motion of an object? 3. State Newton‘s First law of Motion. 4. Write one complete sentence for each term listed below. force friction centripetal force 
inertia muscular force elastic force
gravity
Second law: . The vector sum of the forces on an object is equal to the mass of that object multiplied by the acceleration vector of the object.
The second law states that the net force on an object is equal to the rate of change (that is, the derivative) of its linear momentum p in an inertial reference frame:
The second law can also be stated in terms of an object's acceleration. Since Newton's second law is only valid for constant-mass systems, mass can be taken outside the differentiation operator by the constant factor rule in differentiation. Thus,
where F is the net force applied, m is the mass of the body, and a is the body's acceleration. Thus, the net force applied to a body produces a proportional acceleration. In other words, if a body is accelerating, then there is a force on it. Consistent with the first law, the time derivative of the momentum is non-zero when the momentum changes direction, even if there is no change in its magnitude; such is the case with uniform circular motion. The relationship also implies the conservation of momentum: when the net force on the body is zero, the momentum of the body is constant. Any net force is equal to the rate of change of the momentum.
Young Ji International School / College
Page 23
Newton's second law requires modification if the effects of special relativity are to be taken into account, because at high speeds the approximation that momentum is the product of rest mass and velocity is not accurate. Impulse is a concept frequently used in the analysis of collisions and impacts. For example, a gave the desk acceleration of 1 m/s2. Assume the mass of the desk is 50 kg. The force is: F=mxa = 50kg x 1 m/s2 = 50 N Or F = ma = 50kg x 2 m/s2 = 100 N Concept Review 1. A student pushes a set of beams across a gym floor. She reaches an acceleration of 4 m/s/s. if she had pushed with twice as much force, what acceleration would she have reached? 2. Write one complete sentence for each term listed below. Newton weight
Third law: When one body exerts a force on a second body, the second body simultaneously exerts a force equal in magnitude and opposite in direction on the first body. The third law states that all forces exist in pairs: if one object A exerts a force FA on a second object B, then B simultaneously exerts a force FB on A, and the two forces are equal and opposite: FA = −FB. The third law means that all forces are interactions between different bodies, and thus that there is no such thing as a unidirectional force or a force that acts on only one body. This law is sometimes referred to as the action-reaction law, with FA called the "action" and FB the "reaction". The action and the reaction are simultaneous, and it does not matter which is called the action and which is called reaction; both forces are part of a single interaction, and neither force exists without the other. The two forces in Newton's third law are of the same type (e.g., if the road exerts a forward frictional force on an accelerating car's tires, then it is also a frictional force that Newton's third law predicts for the tires pushing backward on the road). From a conceptual standpoint, Newton's third law is seen when a person walks: they push against the floor, and the floor pushes against the person. Similarly, the tires of a car push against the road while the road pushes back on the tires—the tires and road simultaneously push against each other. In swimming, a person interacts with the water, pushing the water backward, while the water simultaneously pushes the person forward—both the person and the water push against each other. Young Ji International School / College
Page 24
The reaction forces account for the motion in these examples. These forces depend on friction; a person or car on ice, for example, may be unable to exert the action force to produce the needed reaction force. In fluid dynamics, drag (sometimes called air resistance, a type of friction, or fluid resistance, another type of friction or fluid friction) refers to forces acting opposite to the relative motion of any object moving with respect to a surrounding fluid. This can exist between two fluid layers (or surfaces) or a fluid and a solid surface. Unlike other resistive forces, such as dry friction, which are nearly independent of velocity, drag forces depend on velocity. Drag forces always decrease fluid velocity relative to the solid object in the fluid‘s path. Concept Review 1. Identify a pair forces in each of the following situations. a. You are standing on the front edge of a skateboard and carefully step onto the ground. You move forward and the board moves back. b. State Newton‘s thirds law of motion. How does this law describe each force of the pairs of forces in question # 1. Examples of drag Examples of drag include the component of the net aerodynamic or hydrodynamic force acting opposite to the direction of movement of the solid object relative to the Earth as for cars, aircraft and boat hulls; or acting in the same geographical direction of motion as the solid, as for sails attached to a downwind sail boat, or in intermediate directions on a sail depending on points of sail. In the case of viscous drag of fluid in a pipe, drag force on the immobile pipe decreases fluid velocity relative to the pipe. Types of drag Types of drag are generally divided into the following categories: parasitic drag, consisting of form drag, skin friction, interference drag, lift-induced drag, and wave drag (aerodynamics) or wave resistance (ship hydrodynamics). The terminal velocity of an object is the velocity of the object when the sum of the drag force (Fd) and buoyancy equals the downward force of gravity (FG) acting on the object. Since the net force on the object is zero, the object has zero acceleration.[1]
Young Ji International School / College
Page 25
In fluid dynamics, an object is moving at its terminal velocity if its speed is constant due to the restraining force exerted by the fluid through which it is moving. As the speed of an object increases, the drag force acting on the object, resultant of the substance (e.g., air or water) it is passing through, increases. At some speed, the drag or force of resistance will equal the gravitational pull on the object (buoyancy is considered below). At this point the object ceases to accelerate and continues falling at a constant speed called terminal velocity (also called settling velocity). An object moving downward with greater than terminal velocity (for example because it was thrown downwards or it fell from a thinner part of the atmosphere or it changed shape) will slow down until it reaches terminal velocity. Drag depends on the projected area, and this is why objects with a large projected area relative to mass, such as parachutes, have a lower terminal velocity than objects with a small projected area relative to mass, such as bullets. Archimedes’s principle Archimedes' principle indicates that the upward buoyant force that is exerted on a body immersed in a fluid, whether fully or partially submerged, is equal to the weight of the fluid that the body displaces. Archimedes' principle is a law of physics fundamental to fluid mechanics. Archimedes of Syracuse formulated this principle, which bears his name. Archimedes, a Greek scientist who lived over 2, 000 years ago, made similar observations of sinking and floating.
However, he observed objects in other fluids besides just water. He observed how objects behave in gases as well.
Archimedes concluded that an object placed in any fluid is acted upon by an upward force equal to the weight of the fluid displaced by the object.
This statement, Archimedes‘ Principle, applies to any fluid, that is to any liquid or gas.
Concepts Review 1. What causes a sky diver to reach terminal speed? 2. Describe how to forces cause an arrow to fall in a curved path. 3. How can you measure the buoyant force acting on a rock that sinks in water? Potential energy Energy stored in an object due to its position in a force field or in a system due to its configuration. Common types include the gravitational potential energy of an object that depends on its vertical position and mass, the elastic potential
Young Ji International School / College
Page 26
energy of an extended spring, and the electric potential energy of a charge in an electric field. The SI unit for energy is the joule (symbol J).  Potential energy was introduced by the 19th century Scottish engineer and physicist William Rankine, although it has links to Greek philosopher Aristotle's concept of potentiality. Potential energy is associated with forces that act on a body in a way that depends only on the body's position in space. These forces can be represented by a vector at every point in space forming what is known as a vector field of forces, or a force field. If the work of force field acting on a body that moves from a start to an end position is determined only by these two positions, and does not depend on the trajectory of the body, then there is a function known as potential energy that can be evaluated at the two positions to determine this work. Furthermore, the force field is determined by this potential energy and is described as derivable from a potential.
In the case of a bow and arrow, when the archer does work on the bow, drawing the string back, some of the chemical energy of the archer's body is transformed into elastic potential-energy in the bent limbs of the bow. When the string is released, the force between the string and the arrow does work on the arrow. Thus, the potential energy in the bow limbs is transformed into the kinetic energy of the arrow as it takes flight. 
Kinetic energy of an object is the energy that it possesses due to its motion.[1] It is defined as the work needed to accelerate a body of a given mass from rest to its stated velocity. Having gained this energy during its acceleration, the body maintains this kinetic energy unless its speed changes. The same amount of work is done by the body in decelerating from its current speed to a state of rest. In classical mechanics, the kinetic energy of a non-rotating object of mass m traveling at a speed v is . In relativistic mechanics, this is a good approximation only when v is much less than the speed of light.
Young Ji International School / College
Page 27
The cars of a roller coaster reach their maximum kinetic energy when at the bottom of their path. When they start rising, the kinetic energy begins to be converted to gravitational potential energy. The sum of kinetic and potential energy in the system remains constant, ignoring losses to friction . Concept Review 1. Use the conservation of energy to describe the motion of a sled traveling down an icy hill and hitting a snowbank at the button. 2. Write a complete sentence for the term below. a. gravitational potential energy Power Power is the rate of doing work. It is equivalent to an amount of energy consumed per unit time. In the MKS system, the unit of power is the joule per second (J/s), known as the watt in honor of James Watt, the eighteenth-century developer of the steam engine. The integral of power over time defines the work performed. Because this integral depends on the trajectory of the point of application of the force and torque, this calculation of work is said to be path dependent. The same amount of work is done when carrying a load up a flight of stairs whether the person carrying it walks or runs, but more power is needed for running because the work is done in a shorter amount of time. The output power of an electric motor is the product of the torque that the motor generates and the angular velocity of its output shaft. The power involved in moving a vehicle is the product of the traction force of the wheels and the velocity of the vehicle. The rate at which a light bulb converts electrical energy into light and heat is measured in watts—the higher the wattage, the more power, or equivalently the more electrical energy is used per unit time. Power is a measure of how fast work is done. Young Ji International School / College
Page 28
It takes more power to run up a flight of stairs than it takes to walk up. Power is measured in watts, abbreviated W. One watt equals one joule per second. You can find the amount of power developed by using the formula; Power = work done time Horsepower Horsepower (hp) is a unit of measurement of power (the rate at which work is done). There are many different standards and types of horsepower. The most common horsepower—especially for electrical power—is 1 hp = 746 watts. The term was adopted in the late 18th century by Scottish engineer James Watt to compare the output of steam engines with the power of draft horses. It was later expanded to include the output power of other types of piston engines, as well as turbines, electric motors and other machinery
One metric horsepower is needed to lift 75 kilograms (avg. body weight of a person) by 1 meter (3.28 feet) in 1 second. Since power is the rate at which work is done, you first need to know the work you did. The work you do goes into your potential energy at the top of the stairs. the work you do is: work = force x distance = 440 N x 6 m = 2, 640 J You can now find the power power = work done time = 2, 460 J 4s = 660 W Young Ji International School / College
Page 29
Since 746 W equals one horsepower, you can see that your power is almost one horsepower. You could not keep working at this power for very long! Simple machine A simple machine is a mechanical device that changes the direction or magnitude of a force. In general, they can be defined as the simplest mechanisms that use mechanical advantage (also called leverage) to multiply force. Usually the term refers to the six classical simple machines which were defined by Renaissance scientists: Lever Wheel and axle Pulley Inclined plane Wedge Screw A simple machine uses a single applied force to do work against a single load force. Ignoring friction losses, the work done on the load is equal to the work done by the applied force. The machine can increase the amount of the output force, at the cost of a proportional decrease in the distance moved by the load. The ratio of the output to the applied force is called the mechanical advantage. Simple machines can be regarded as the elementary "building blocks" of which all more complicated machines (sometimes called "compound machines") are composed. For example, wheels, levers, and pulleys are all used in the mechanism of a bicycle. The mechanical advantage of a compound machine is just the product of the mechanical advantages of the simple machines of which it is composed. Although they continue to be of great importance in mechanics and applied science, modern mechanics has moved beyond the view of the simple machines as the ultimate building blocks of which all machines are composed, which arose in the Renaissance as a neoclassical amplification of ancient Greek texts on technology. The great variety and sophistication of modern machine linkages, which arose during the Industrial Revolution, is inadequately described by these six simple categories. As a result, various post-Renaissance authors have compiled expanded lists of "simple machines", often using terms like basic machines, compound machines, or machine elements to distinguish them from the classical simple machines above. Lever A lever is a machine consisting of a beam or rigid rod pivoted at a fixed hinge, or fulcrum. It is one of the six simple machines identified by Renaissance scientists. The word comes from the French lever, "to raise", cf. a levant. A lever amplifies an input force to provide a greater output force, which is said to provide leverage. The ratio of the output force to the input force is the mechanical advantage of the lever. Young Ji International School / College
Page 30
Lever balance Mechanical advantage Mechanical advantage is a measure of the force amplification achieved by using a tool, mechanical device or machine system. Ideally, the device preserves the input power and simply trades off forces against movement to obtain a desired amplification in the output force. The model for this is the law of the lever. Machine components designed to manage forces and movement in this way are called mechanisms. An ideal mechanism transmits power without adding to or subtracting from it. This means the ideal mechanism does not include a power source, and is frictionless and constructed from rigid bodies that do not deflect or wear. The performance of a real system relative to this ideal is expressed in terms of efficiency factors that take into account friction, deformation and wear. Concepts Review 1. Give two ways machines help work. 2. How can a wheelbarrow and a fishing pole both be levers? 3. Write one complete sentence for each term below. a. Simple machine b. Effort c. Output force d. Lever e. Fulcrum f. Mechanical advantage Pulleys A pulley is a wheel on an axle that is designed to support movement and change of direction of a cable or belt along its circumference. Pulleys are used in a variety of ways to lift loads, apply forces, and to transmit power. In nautical contexts, the assembly of wheel, axle, and supporting shell is referred to as a "block." A pulley is also called a sheave or drum and may have a groove between two flanges around its circumference. The drive element of a pulley system can be a rope, cable, belt, or chain that runs over the pulley inside the groove.
Young Ji International School / College
Page 31
Pulley A pulley is a grooved wheel that turns by the action of a rope in the groove. A fixed pulley helps make work easier by changing the direction of the effort. It is easier to full down on a rope than to lift up the television with your bare hands. However, a fixed pulley does not multiply the effort. The effort used to lift the television is the same as the output force of the machine. When the effort and the output force of a machine are the same, what is the MA of the machine? You can find the MA of any machine as you did for a lever. In this case:
MA = output force Effort = 400 N 400 N =1 A wheel and axle can help your force reach places it could not reach otherwise A wheel and axle is made of a handle or axle attached to the center of a wheel. The radius is the length between the center and edge of a circle. The kind of wheel is called a gear. A gear is a wheel teeth cut into the rim.
Inclined Planes Up to now you have been looking at simple machines that have moving parts. Now look at a simple machine that has no moving parts. It is called an inclined plane.
An inclined plane is a straight, slanted surface. A ramp is an example of an inclined plane. Two kinds of Inclined Planes Two other simple machines are actually kinds of inclined planes. A wedge, like an inclined plane, has s slanted surface. Some wedges, in fact have two slanted surface. Unlike an inclined plane, however, a wedge must Young Ji International School / College
Page 32
be moved in order to do work. You hammer a wedge in one direction. It lifts or splits apart an object in other direction; a wedge helps your effort get under heavy objects, or inside them.
A screw is another kind of inclined plane.
A screw is actually an inclined plane wrapped around a central bar. The steeper the inclined plane is, the farther apart the threads of a screw are. Various ways of rigging a tackle A set of pulleys assembled so that they rotate independently on the same axle form a block. Two blocks with a rope attached to one of the blocks and threaded through the two sets of pulleys form a block and tackle. A block and tackle is assembled so one block is attached to fixed mounting point and the other is attached to the moving load. The mechanical advantage of the block and tackle is equal to the number of parts of the rope that support the moving block. Concept Review 1. (a) You have a pulley and some rope. There is a book on ceiling and a hook on a heavy crate. Describe two ways of using the pulley to lift the crate from the floor. (b) A wheel has a radius of 4 cm. it is attached to an axle that has a radius of 2 cm. how many times may the wheel and axle multiply an effort of 2o N applied to the wheel? 2. How can an inclined plane help do work? 3. How are wedges and screws kinds of inclined planes? 4. Write one complete sentence for each term listed below. Pulley gear Wheel and axle inclined plane Work Output and Input
Work input is amount of work you put into a machine when you use it.
Work output is the amount of work you obtain from a machine when you use it.
The efficiency of a machine is a measure of the useful work a machine can do. It is usually expressed as a percent:
Concept Review 1. How does friction affect the amount of work you get from a machine? Young Ji International School / College
Page 33
2. In a machine, which is usually greater, the work output or the work input? Why? 3. Write one complete sentence for each term listed below. Work input work output efficiency
Chapter 3:
Matter and Its Changes
Matter is anything that takes up space and has mass. All matter is composed of ―building blocks‖. The structure of these building blocks determines the structure of the matter you observe. Think about when you were younger and played with snap-together blocks. You could snap the blocks together in many ways to build cars, ships or buildings. Matter is put together in a similar way. The building blocks of matter are atoms. The arrangement and types of atoms give matter its properties. Atoms combine, like the block snapping together, to form many different types of matter. The Structure of Atoms Let‘s construct a mental model of the internal structure of an atom. There basic particles make up an atom – protons, neutrons, and electrons. Protons and neutrons are located in the center of an atom and make up its nucleus. Protons are particles that have a positive electric charge. Neutrons are particles that have no electric charge. The nucleus, therefore, has a positive charge because of the positively charged protons in it. This positive electric charge of the nucleus is balanced by the electrons of the atom. Electrons are negatively charged particles that circle the nucleus. Concept Review 1. List two factors are true of all matter. 2. What is the electric charge of each of the particles of an atom?
Young Ji International School / College
Page 34
Chapter 4: Minerals A mineral is a naturally occurring substance that is solid and inorganic represent able by a chemical formula, usually a biogenic, and has an ordered diatomic. It is different from a rock, which can be an aggregate of minerals or nonminerals and does not have a specific chemical composition. The exact definition of a mineral is under debate, especially with respect to the requirement a valid species is a biogenic, and to a lesser extent with regard to it having an ordered atomic structure. The study of minerals is called mineralogy.
Amethyst, a variety of quartz Although more than 400 different minerals are found on earth, they all share five characteristics. Let‘s look at rock salt, diamonds and graphite, and the characteristics they share. First, all minerals are formed by natural processes. Rock salt, diamonds, and graphite minerals because they formed naturally. You‘ll investigate more about these processes later in this lesson. Second, minerals are nonliving. They aren‘t alive and never were alive. Diamonds and coal are both made from the element carbon, but they are not both minerals. Diamonds form from nonliving carbon inside earth, whereas cola is made of carbon from living things. The third characteristics that minerals share are that they are all solids. Remember that all solids have a definite volume and shape. A gas such as air or a liquid such as water isn‘t a mineral because its shape changes. Fourth, every mineral is an element or compound with a chemical composition unique to that mineral. Rock salt‘ composition gives it is a distinctive flavor. Finally, the atoms in minerals are arranged in a pattern, repeated over and over again. A crystals is a solid in which the atoms are arranged in repeating patterns.
Young Ji International School / College
Page 35
Basic definition The general definition of a mineral encompasses the following criteria: Naturally occurring Stable at room temperature Represented by a chemical formula Usually a biogenic (not resulting from the activity of living organisms) Ordered atomic arrangement The first three general characteristics are less debated than the last two. The first criterion means that a mineral has to form by a natural process, which excludes anthropogenic compounds. Stability at room temperature, in the simplest sense, is synonymous to the mineral being solid. More specifically, a compound has to be stable or metastable at 25 °C. Classical examples of exceptions to this rule include native mercury, which crystallizes at −39 °C, and water ice, which is solid only below 0 °C; as these two minerals were described prior to 1959, they were grandfathered by the International Mineralogical Association (IMA). Modern advances have included extensive study of liquid crystals, which also extensively involve mineralogy. Minerals are chemical compounds, and as such they can be described by fixed or a variable formula. Many mineral groups and species are composed of a solid solution; pure substances are not usually found because of contamination or chemical substitution. For example, the olivine group is described by the variable formula (Mg, Fe)2SiO4, which is a solid solution of two end-member species, magnesiumrich forsterite and iron-rich fayalite, which are described by a fixed chemical formula. Mineral species themselves could have a variable compositions, such as the sulfide mackinawite, (Fe, Ni)9S8, which is mostly a ferrous sulfide, but has a very significant nickel impurity that is reflected in its formula. [1]
The requirement of a valid mineral species to be a biogenic has also been described as similar to have to be inorganic; however, this criterion is imprecise and organic compounds have been assigned a separate classification branch. Finally, the requirement of an ordered atomic arrangement is usually synonymous to being crystalline; however, crystals are periodic in addition to being ordered, so the broader criterion is used instead. The presence of an ordered atomic arrangement translates to a variety of macroscopic physical properties, such as crystal form, hardness, and cleavage. There have been several recent proposals to amend the definition to consider biogenic or amorphous substances as minerals. The formal definition of a mineral approved by the IMA in 1995: "A mineral is an element or chemical compound that is normally crystalline and that has been formed as a result of geological processes." In addition, biogenic substances were explicitly excluded: "Biogenic substances are chemical compounds produced entirely by biological processes without a geological component (e.g., urinary calculi, oxalate crystals in Young Ji International School / College
Page 36
plant tissues, shells of marine molluscs, etc.) and are not regarded as minerals. However, if geological processes were involved in the genesis of the compound, then the product can be accepted as a mineral.‖ Recent advances Mineral classification schemes and their definitions are evolving to match recent advances in mineral science. Recent changes have included the addition of an organic class, in both the new Dana and the Strunz classification schemes.[7][8]The organic class includes a very rare group of minerals with hydrocarbons. The IMA Commission on New Minerals and Mineral Names adopted in 2009 a hierarchical scheme for the naming and classification of mineral groups and group names and established seven commissions and four working groups to review and classify minerals into an official listing of their published names. According to these new rules, "mineral species can be grouped in a number of different ways, on the basis of chemistry, crystal structure, occurrence, association, genetic history, or resource, for example, depending on the purpose to be served by the classification." The Nickel (1995) exclusion of biogenic substances was not universally adhered to. For example, Lowenstam (1981) stated that "organisms are capable of forming a diverse array of minerals, some of which cannot be formed inorganically in the biosphere." The distinction is a matter of classification and less to do with the constituents of the minerals themselves. Skinner (2005) views all solids as potential minerals and includes biominerals in the mineral kingdom, which are those that are created by the metabolic activities of organisms. Skinner expanded the previous definition of a mineral to classify "element or compound, amorphous or crystalline, formed through biogeochemical processes," as a mineral. Recent advances in high-resolution genetic and x-ray absorption spectroscopy is opening new revelations on the biogeochemical relations between microorganisms and minerals that may make Nickel's (1995) biogenic mineral exclusion obsolete and Skinner's (2005) biogenic mineral inclusion a necessity.  For example, the IMA commissioned 'Environmental Mineralogy and Geochemistry Working Group ‗deals with minerals in the hydrosphere, atmosphere, and biosphere. Mineral forming microorganisms inhabit the areas that this working group deals with. These organisms exist on nearly every rock, soil, and particle surface spanning the globe reaching depths at 1600 metres below the sea floor (possibly further) and 70 kilometres into the stratosphere (possibly entering the mesosphere). Biologists and geologists have started to research and appreciate the magnitude of mineral geoengineering that these creatures are capable of. Bacteria have contributed to the formation of minerals for billions of years and critically define the biogeochemical cycles on this planet. Microorganisms can precipitate metals from solution contributing to the formation of ore deposits in addition to their ability to catalyze mineral dissolution, to respire, precipitate, and form minerals. Young Ji International School / College
Page 37
Prior to the International Mineralogical Association's listing, over 60 biominerals had been discovered, named, and published. These minerals (a sub-set tabulated in Lowenstam (1981) are considered minerals proper according to the Skinner (2005) definition. These biominerals are not listed in the International Mineral Association official list of mineral names, however, many of these biomineral representatives are distributed amongst the 78 mineral classes listed in the Dana classification scheme. Another rare class of minerals (primarily biological in origin) includes the mineral liquid crystals that are crystalline and liquid at the same time. To date over 80,000 liquid crystalline compounds have been identified. Concerning the use of the term ―mineral‖ to name this family of liquid crystals, one can argue that the term inorganic would be more appropriate. However, inorganic liquid crystals have long been used for organometallic liquid crystals. Therefore, in order to avoid any confusion between these fairly chemically different families, and taking into account that a large number of these liquid crystals occur naturally in nature, we think that the use of the old fashioned but adequate ―mineral‖ adjective taken sensus largo is more specific that an alternative such as ―purely inorganic‖, to name this subclass of the inorganic liquid crystals family. The Skinner (2005) definition of a mineral takes this matter into account by stating that a mineral can be crystalline or amorphous. Liquid mineral crystals are amorphous. Biominerals and liquid mineral crystals, however, are not the primary form of minerals, most are geological in origin, but these groups do help to identify at the margins of what constitutes a mineral proper. The formal Nickel (1995) definition explicitly mentioned crystalline nature as a key to defining a substance as a mineral. A 2011 article defined icosahedrite, an aluminium-iron-copper alloy as mineral; named for its unique natural icosahedral symmetry, it is also a quasicrystal. Unlike a true crystal, quasicrystals are ordered but not periodic. Rocks, ores, and gems
Schist is a metamorphic rock characterized by an abundance of platy minerals. In this example, the rock has prominent sillimaniteporphyroblasts as large as 3 cm (1.2 in). Minerals are not equivalent to rocks. Whereas a mineral is a naturally occurring usually solid substance, stable at room temperature, represent able by a chemical Young Ji International School / College
Page 38
formula, usually abiogenic, and has an ordered atomic structure, a rock is either an aggregate of one or more minerals, or not composed of minerals at all.  Rocks like limestone or quartzite are composed primarily of one mineral— calcite or aragonite in the case of limestone, and quartz in the latter case. Other rocks can be defined by relative abundances of key (essential) minerals; a granite is defined by proportions of quartz, alkali feldspar, and plagioclase feldspar. The other minerals in the rock are termed accessory, and do not greatly affect the bulk composition of the rock. Rocks can also be composed entirely of non-mineral material; coal is a sedimentary rock composed primarily of organically derived carbon. In rocks, some mineral species and groups are much more abundant than others; these are termed the rock-forming minerals. The major examples of these are quartz, the feldspars, the micas, the amphiboles, the pyroxenes, the olivines, and calcite; except the last one, all of the minerals are silicates. [32] Overall, around 150 minerals are considered particularly important, whether in terms of their abundance or aesthetic value in terms of collecting. Commercially valuable minerals and rocks are referred to as industrial minerals. For example, muscovite, a white mica, can be used for windows (sometimes referred to as isinglass), as a filler, or as an insulator. [34] Ores are minerals that have a high concentration of a certain element, typically a metal. Examples are cinnabar (HgS), an ore of mercury, sphalerite (ZnS), an ore of zinc, or cassiterite (SnO2), an ore of tin. Gems are minerals with an ornamental value, and are distinguished from non-gems by their beauty, durability, and usually, rarity. There are about 20 mineral species that qualify as gem minerals, which constitute about 35 of the most common gemstones. Gem minerals are often present in several varieties, and so one mineral can account for several different gemstones; for example, ruby and sapphire are both corundum, Al2O3. Nomenclature and classification In general, a mineral is defined as naturally occurring solid, that is stable at room temperature, represent able by a chemical formula, usually abiogenic, and has an ordered atomic structure. However, a mineral can be also narrowed down in terms of a mineral group, series, species, or variety, in order from most broad to least broad. The basic level of definition is that of mineral species, which is distinguished from other species by specific and unique chemical and physical properties. For example, quartz is defined by its formula, SiO2, and a specific crystalline structure that distinguishes it from other minerals with the same chemical formula (termed polymorphs). When there exists a range of composition between two minerals species, a mineral series is defined.  For *example, the biotite series is represented by variable amounts of the end members phlogopite, siderophyllite, annite, and eastonite. In contrast, a mineral group is a grouping of mineral species with some common chemical properties that share a crystal structure. The pyroxene group has a common Young Ji International School / College
Page 39
formula of XY(Si,Al)2O6, where X and Y are both cations, with X typically bigger than Y; the pyroxenes are single-chain silicates that crystallize in either the orthorhombic or monoclinic crystal systems. Finally, a mineral variety is a specific type of mineral species that differs by some physical characteristic, such as color or crystal habit. An example is amethyst, which is a purple variety of quartz. Two common classifications are used for minerals; both the Dana and Strunz classifications rely on the composition of the mineral, specifically with regards to important chemical groups, and its structure. The Dana System of Mineralogy was first published in 1837 by James Dwight Dana, a leading geologist of his time; it is in its eighth edition (1997 ed.). The Dana classification, assigns a four-part number to a mineral species. First is its class, based on important compositional groups; next, the type gives the ratio of cations to anions in the mineral; finally, the last two numbers group minerals by structural similarity with a given type or class. The less commonly used Strunz classification, named for German mineralogist Karl Hugo Strunz, is based on the Dana system, but combines both chemical and structural criteria, the latter with regards to distribution of chemical bonds. There are over 4,660 approved mineral species. They are most commonly named after a person (45%), followed by discovery location (23%); names based on chemical composition (14%) and physical properties (8%) are the two other major groups of mineral name etymologies. The common suffix -ite of mineral names descends from the ancient Greek suffix - ί τ η ς (-ites), meaning "connected with or belonging to". Concept Review 1. 2. 3. 4. 5.
List briefly the five conditions a substance must meet to be a mineral. To what crystals system does halite belong? What is the silicate minerals made of? What are two ways that minerals can from? Apply: Is ice a mineral? Explain.
Mineral chemistry
Hübnerite, the manganese-rich end-member of the wolframite series, with minor quartz in the background Young Ji International School / College
Page 40
The abundance and diversity of minerals is controlled directly by their chemistry, in turn dependent on elemental abundances in the Earth. The majority of minerals observed are derived from the Earth's crust. Eight elements account for most of the key components of minerals, due to their abundance in the crust. These eight elements, summing to over 98% of the crust by weight, are, in order of decreasing abundance: oxygen, silicon,aluminium, iron, magnesium, calcium, sodium and potassium. Oxygen and silicon are by far the two most important — oxygen composes 46.6% of the crust by weight, and silicon accounts for 27.7%. The minerals that form are directly controlled by the bulk chemistry of the parent body. For example, a magma rich in iron and magnesium will form mafic minerals, such as olivine and the pyroxenes; in contrast, a more silica-rich magma will crystallize to form minerals than incorporate more SiO 2, such as the feldspars and quartz. In a limestone, calcite or aragonite (both CaCO3) form because the rock is rich in calcium and carbonate. A corollary is that a mineral will not be found in a rock whose bulk chemistry does not resemble the bulk chemistry of a given mineral with the exception of trace minerals. For example, kyanite, Al2SiO5 forms from the metamorphism of aluminiumrich shales; it would not likely occur in aluminum-poor rock, such quartzite. The chemical composition may vary between end member species of a mineral series. For example, the plagioclasefeldspars comprise a continuous series from sodium-rich end member albite (NaAlSi3O8) to calciumrich anorthite(CaAl2Si2O8) with four recognized intermediate varieties between them (given in order from sodiumto calciumrich):oligoclase, andesine, labradorite, and bytownite. Other examples of series include the olivine series of magnesium-rich forsterite and iron-rich fayalite, and the wolframite series of manganese-rich hübnerite and ironrich ferberite. Chemical substitution and coordination polyhedra explain this common feature of minerals. In nature, minerals are not pure substances, and are contaminated by whatever other elements are present in the given chemical system. As a result, it is possible for one element to be substituted for another. Chemical substitution will occur between ions of a similar size and charge; for example, K + will not substitute for Si4+ because of chemical and structural incompatibilities caused by a big difference in size and charge. A common example of chemical substitution is that of Si4+ by Al3+, which are close in charge, size, and abundance in the crust. In the example of plagioclase, there are three cases of substitution. Feldspars are all framework silicates, which have a silicon-oxygen ratio of 2:1, and the space for other elements is given by the substitution of Si4+ by Al3+ to give a base unit of [AlSi3O8]-; without the substitution, the formula would be charge-balanced as SiO2, giving Young Ji International School / College
Page 41
quartz. The significance of this structural property will be explained further by coordination polyhedra. The second substitution occurs between Na + and Ca2+; however, the difference in charge has to accounted for by making a second substitution of Si4+ by Al3+. Coordination polyhedra are geometric representation of how a cation is surrounded by an anion. In mineralogy, due its abundance in the crust, coordination polyhedra are usually considered in terms of oxygen. The base unit of silicate minerals is the silica tetrahedron — one Si4+ surrounded by four O2-. An alternate way of describing the coordination of the silicate is by a number: in the case of the silica tetrahedron, the silicon is said to have a coordination number of 4. Various cations have a specific range of possible coordination numbers; for silicon, it is almost always 4, except for very high-pressure minerals where compound is compressed such that silicon is in six-fold (octahedral) coordination by oxygen. Bigger cations have a bigger coordination number because of the increase in relative size as compared to oxygen (the last orbital subshell of heavier atoms is different too). Changes in coordination numbers between leads to physical and mineralogical differences; for example, at high pressure such as in the mantle, many minerals, especially silicates such as olivine and garnet will change to a perovskite structure, where silicon is in octahedral coordination. Another example are the aluminosilicates kyanite, andalusite, and sillimanite (polymorphs, as they share the formula Al2SiO5), which differ by the coordination number of the Al3+; these minerals transition from one another as a response to changes in pressure and temperature. In the case of silicate materials, the substitution of Si4+ by Al3+ allows for a variety of minerals because of the need to balance charges.
When minerals react, the products will sometimes assume the shape of the reagent; the product mineral is termed to be a pseudomorph of (or after) the reagent. Illustrated here is a pseudomorph of kaolinite after orthoclase. Here, the pseudomorph preserved the Carlsbad twinning common in orthoclase. Changes in temperature and pressure, and composition alter the mineralogy of a rock sample. Changes in composition can be caused by processes such as weathering or metasomatism (hydrothermal alteration). Changes in temperature and pressure occur when the host rock undergoes tectonic or magmatic movement into differing physical regimes. Changes in thermodynamic conditions make it favorable for mineral assemblages to react with each other to produce new minerals; as such, it is possible for two rocks to have an identical or a very similar bulk rock chemistry without having a similar mineralogy. This process of mineralogical alteration is Young Ji International School / College
Page 42
related to the rock cycle. An example of a series of mineral reactions is illustrated as follows. Orthoclase feldspar (KAlSi3O8) is a mineral commonly found in granite, a plutonicigneous rock. When exposed to weathering, it reacts to form kaolinite(Al2Si2O5(OH)4, a sedimentary mineral, and silicic acid): 2 KAlSi3O8 + 5 H2O + 2 H+ → Al2Si2O5(OH)4 + 4 H2SiO3 + 2 K+ Under low-grade metamorphic conditions, kaolinite reacts with quartz to form pyrophyllite (Al2Si4O10(OH)2): Al2Si2O5(OH)4 + SiO2 → Al2Si4O10(OH)2 + H2O As metamorphic grade increases, the pyrophyllite reacts to form kyanite and quartz: Al2Si4O10(OH)2 → Al2SiO5 + 3 SiO2 + H2O Alternatively, a mineral may change its crystal structure as a consequence of changes in temperature and pressure without reacting. For example, quartz will change into a variety of its SiO2 polymorphs, such as tridymite and cristobalite at high temperatures, and coesite at high pressures. Physical properties of minerals Classifying minerals ranges from simple to difficult. A mineral can be identified by several physical properties, some of them being sufficient for full identification without equivocation. In other cases, minerals can only be classified by more complex optical, chemical or X-ray diffraction analysis; these methods, however, can be costly and time-consuming. Physical properties applied for classification include crystal structure and habit, hardness, luster, diaphaneity, color, streak, cleavage and fracture, and specific gravity. Other less general tests include fluorescence, phosphorescence,magnetism, radioactivity, tenacity (response to mechanical induced changes of shape or form), piezoelectricity and reactivity to dilute acids. Crystal structure and habit
Topaz has a characteristic orthorhombic elongated crystal shape.
Young Ji International School / College
Page 43
Crystal structure results from the orderly geometric spatial arrangement of atoms in the internal structure of a mineral. This crystal structure is based on regular internal atomic or ionic arrangement that is often expressed in the geometric form that the crystal takes. Even when the mineral grains are too small to see or are irregularly shaped, the underlying crystal structure is always periodic and can be determined by X-ray diffraction. Minerals are typically described by their symmetry content. Crystals are restricted to 32 point groups, which differ by their symmetry. These groups are classified in turn into more broad categories, the most encompassing of these being the six crystal families. These families can be described by the relative lengths of the three crystallographic axes, and the angles between them; these relationships correspond to the symmetry operations that define the narrower point groups. They are summarized below; a, b, and c represent the axes, and α, β, γ represent the angle opposite the respective crystallographic axis (e.g. α is the angle opposite the aaxis, viz. the angle between the b and c axes): Crystal family Lengths Angles
Common examples
Isometric
a=b=c
α=β=γ=90°
Garnet, halite, pyrite
Tetragonal
a=b≠c
α=β=γ=90°
Rutile, zircon, andalusite
Orthorhombic a≠b≠c
α=β=γ=90°
Olivine, aragonite, orthopyroxenes
Hexagonal
a=b≠c
α=β=90°, γ=120°
Quartz, calcite, tourmaline
Monoclinic
a≠b≠c
α=γ=90°, β≠90°
Clinopyroxenes, orthoclase, gypsum
Triclinic
a≠b≠c
α≠β≠γ≠90°
Anorthite, albite, kyanite
The hexagonal crystal family is also split into two crystal systems — the trigonal, which has a three-fold axis of symmetry, and the hexagonal, which has a six-fold axis of symmetry. Chemistry and crystal structure together define a mineral. With a restriction to 32 point groups, minerals of different chemistry may have identical crystal structure. For example, halite (NaCl), galena (PbS), and periclase (MgO) all belong to the hex octahedral point group (isometric family), as they have a similar stoichiometry between their different constituent elements. In contrast, polymorphs are groupings of minerals that share a chemical formula but have a different structure. For example, pyrite and marcasite, both iron sulfides, have the formula FeS2; however, the former is isometric while the latter is orthorhombic. This polymorphism extends to other sulfides with the generic AX2 formula; these two groups are collectively known as the pyrite and parasite groups. Young Ji International School / College
Page 44
Differences in crystal structure and chemistry greatly influence other physical properties of the mineral. The carbon allotropes diamond and graphite have vastly different properties; diamond is the hardest natural substance, has an adamantine luster, and belongs to the isometric crystal family, whereas as graphite is very soft, has a greasy luster, and crystallizes in the hexagonal family. This difference is accounted by differences in bonding. In diamond, the carbons are in sp 3 hybrid orbital‘s, which means they form a framework where each carbon is covalently bonded to three neighbors in a tetrahedral fashion; on the other hand, graphite is composed of sheets of carbons in sp2 hybrid orbital‘s, where each carbon is bonded covalently to only two others. These sheets are held together by much weaker van der Waals forces, and this discrepancy translates to big macroscopic differences.

Contact twins, as seen in spinel Twinning is the intergrowth of two or more crystal of a single mineral species. The geometry of the twinning is controlled by the mineral's symmetry. As a result, there are several types of twins, including contact twins, reticulated twins, geniculated twins, penetration twins, cyclic twins, and polysynthetic twins. Contact, or simple twins, consists of two crystals joined at a plane; this type of twinning is common in spinel. Reticulated twins, common in rutile, are interlocking crystals resembling netting. Geniculated twins have a bend in the middle that is caused by start of the twin. Penetration twins consist of two single crystals that have grown into each other; examples of this twinning include cross-shaped staurolite twins and Carlsbad twinning in orthoclase. Cyclic twins are caused by repeated twinning around a rotation axis.
Mohs scale of mineral hardness
Diamond is the hardest natural material, and has a Mohs hardness of 10. Young Ji International School / College
Page 45
The hardness of a mineral defines how much it can resist scratching. This physical property is controlled by the chemical composition and crystalline structure of a mineral. A mineral's hardness is not necessarily constant for all sides, which is a function of its structure; crystallographic weakness renders some directions softer than others. An example of this property exists in kyanite, which has a Mohs hardness of 5½ parallel to [001] but 7 parallel to [100]. The most common scale of measurement is the ordinal Mohs hardness scale. Defined by ten indicators, a mineral with a higher index scratches those below it. The scale ranges from talc, a phyllosilicate, to diamond, a carbon polymorph that is the hardest natural material. The scale is provided below: Mohs hardness
Mineral
Chemical formula
1
Talc
Mg3Si4O10(OH)2
2
Gypsum
CaSO4·2H2O
3
Calcite
CaCO3
4
Fluorite
CaF2
5
Apatite
Ca5(PO4)3(OH,Cl,F)
6
Orthoclase KAlSi3O8
7
Quartz
SiO2
8
Topaz
Al2SiO4(OH,F)2
9
Corundum Al2O3
10
Diamond
C
Luster (mineralogy)
Pyrite has a metallic luster. Luster indicates how light reflects from the mineral's surface, with regards to its quality and intensity. There are numerous qualitative terms used to describe this property, which are split into metallic and non-metallic categories. Metallic and submetallic minerals have high reflectivity like metal; examples of minerals with this luster are galena and pyrite. Non-metallic luster include: adamantine, such as in diamond; vitreous, which is a glassy luster very common in silicate minerals; pearly, such as in talc and apophyllite, resinous, such as members of the garnet group, silky which common in fibrous minerals such as asbestiform chrysotile. Young Ji International School / College
Page 46
The diaphaneity of a mineral describes the ability of light to pass through it. Transparent minerals do not diminish the intensity of light passing through it. An example of such a mineral is muscovite (potassium mica); some varieties are sufficiently clear to have been used for windows. Translucent minerals allow some light to pass, but less than those that are transparent. Jadeite and nephrite(mineral forms of jade are examples of minerals with this property). Minerals that do not allow light to pass are called opaque. The diaphaneity of a mineral depends on thickness of the sample. When a mineral is sufficiently thin (e.g., in a thin section for petrography), it may become transparent even if that property is not seen in hand sample. In contrast, some minerals, such as hematite or pyrite are opaque even in thin-section. Streak (mineralogy)

Color is the most obvious property of a mineral, but it is often nondiagnostic. It is caused by electromagnetic radiation interacting with electrons (except in the case of incandescence, which does not apply to minerals). Two broad classes of elements are defined with regards to their contribution to a mineral's color. Idiochromatic elements are essential to a mineral's composition; their contribution to a mineral's color is diagnostic. Examples of such minerals are malachite (green) and azurite (blue). In contrast, all chromatic elements in minerals are present in trace amounts as impurities. An example of such a mineral would be the ruby and sapphire varieties of the mineral corundum. The colors of pseudo chromatic minerals are the result of interference of light waves. Examples include opal,labradorite, ammolite and bornite.
Young Ji International School / College
Page 47
In addition to simple body color, minerals can have various other distinctive optical properties, such as play of colours,asterism, chatoyancy, iridescence, tarnish, and pleochroism. Several of these properties involve variability in color. Play of color, such as in opal, results in the sample reflecting different colors as it is turned, while pleochroism describes the change in color as light passes through a mineral in a different orientation. Iridescence is a variety of the play of colors where light scatters off a coating on the surface of crystal, cleavage planes, or off layers having minor gradations in chemistry. In contrast, the play of colors in opal is caused by light refracting from ordered microscopic silica spheres within its physical structure. Chatoyancy ("cat's eye") is the wavy banding of color that is observed as the sample is rotated; asterism, a variety of chatoyancy, gives the appearance of a star on the mineral grain. The latter property is particularly common in gem-quality corundum. The streak of a mineral refers to the color of a mineral in powdered form, which may or may not be identical to its body color. The most common way of testing this property is done with a streak plate, which is made out of porcelain and colored either white or black. The streak of a mineral is independent of trace elements or any weathering surface. A common example of this property is illustrated with hematite, which is colored black, silver, or red in hand sample, but has a cherry-red to reddishbrown streak. Streak is more often distinctive for metallic minerals, in contrast to non-metallic minerals whose body color is created by all chromatic elements. Streak testing is constrained by the hardness of the mineral, as those harder than 7 powders the streak plate instead. Cleavage (crystal) and Fracture (mineralogy)
Perfect basal cleavage as seen in biotite (black), and good cleavage seen in the matrix (pink orthoclase). By definition, minerals have a characteristic atomic arrangement. Weakness in this crystalline structure causes planes of weakness, and the breakage of a mineral along such planes is termed cleavage. The quality of cleavage can be described based on how cleanly and easily the mineral breaks; common descriptors, Young Ji International School / College
Page 48
in order of decreasing quality, are "perfect", "good", "distinct", and "poor". In particularly transparent mineral, or in thin-section, cleavage can be seen a series of parallel lines marking the planar surfaces when viewed at a side. Cleavage is not a universal property among minerals; for example, quartz, consisting of extensively interconnected silica tetrahedra, does not have a crystallographic weakness which would allow it to cleave. In contrast, micas, which have perfect basal cleavage, consist of sheets of silica tetrahedra which are very weakly held together. As cleavage is a function of crystallography, there are a variety of cleavage types. Cleavage occurs typically in either one, two, three, four, or six directions. Basal cleavage in one direction is a distinctive property of the micas. Two-directional cleavage is described as prismatic, and occurs in minerals such as the amphiboles and pyroxenes. Minerals such as galena or halite have cubic (or isometric) cleavage in three directions, at 90°; when three directions of cleavage are present, but not at 90°, such as in calcite or rhodochrosite, it is termed rhombohedra cleavage. Octahedral cleavage (four directions) is present in fluorite and diamond, and sphalerite has six-directional dodecahedral cleavage. Minerals with many cleavages might not break equally well in all of the directions; for example, calcite has good cleavage in three direction, but gypsum has perfect cleavage in one direction, and poor cleavage in two other directions. Angles between cleavage planes vary between minerals. For example, as the amphiboles are double-chain silicates and the pyroxenes are single-chain silicates, the angle between their cleavage planes is different. The pyroxenes cleave in two directions at approximately 90°, whereas the amphiboles distinctively cleave in two directions separated by approximately 120° and 60°. The cleavage angles can be measured with a contact goniometer, which is similar to a protractor. Parting, sometimes called "false cleavage", is similar in appearance to cleavage but is instead produced by structural defects in the mineral as opposed to systematic weakness. Parting varies from crystal to crystal of a mineral, whereas all crystals of a given mineral will cleave if the atomic structure allows for that property. In general, parting is caused by some stress applied to a crystal. The sources of the stresses include deformation (e.g. an increase in pressure), exsolution, or twinning. Minerals that often display parting include the pyroxenes, hematite, magnetite, and corundum. When a mineral is broken in a direction that does not correspond to a plane of cleavage, it is termed to have been fractured. There are several types of uneven fracture. The classic example is conchoidal fracture, like that of quartz; rounded surfaces are created, which are marked by smooth curved lines. This type of fracture occurs only in very homogeneous minerals. Other types of fracture are fibrous, splintery, and hackly. The latter describes a break along a rough, jagged surface; an example of this property is found in native copper. Tenacity is related to both cleavage and fracture. Whereas fracture and cleavage describes the surfaces that are created when a mineral is broken, tenacity describes how resistant a mineral is to such breaking. Minerals can be described as brittle, ductile, malleable, sectile, flexible, or elastic. Young Ji International School / College
Page 49
Specific gravity
Galena, PbS, is a mineral with a high specific gravity. Specific gravity numerically describes the density of a mineral. The dimensions of density are mass divided by volume with units: kg/m3 or g/cm3. Specific gravity measures how much water a mineral sample displaces. Defined as the quotient of the mass of the sample and difference between the weight of the sample in air and its corresponding weight in water, specific gravity is a unitless ratio. Among most minerals, this property is not diagnostic. Rock forming minerals — typically silicates or occasionally carbonates — have a specific gravity of 2.5–3.5. High specific gravity is a diagnostic property of a mineral. A variation in chemistry (and consequently, mineral class) correlates to a change in specific gravity. Among more common minerals, oxides and sulfides tend to have a higher specific gravity as they include elements with higher atomic mass. A generalization is that minerals with metallic or adamantine lustre tend to have higher specific gravities than those having a non-metallic to dull lustre. For example, hematite, Fe 2O3, has a specific gravity of 5.26 while galena, PbS, has a specific gravity of 7.2–7.6, which is a result of their high iron and lead content, respectively. A very high specific gravity becomes very pronounced in native metals; kamacite, an iron-nickel alloy common in iron meteorites has a specific gravity of 7.9, and gold has an observed specific gravity between 15 and 19.3.
Other properties
Carnotite (yellow) is a radioactive uranium-bearing mineral.
Young Ji International School / College
Page 50
Other properties can be used to diagnose minerals. These are less general, and apply to specific minerals. Dropping dilute acid (often 10% HCl) aids in distinguishing carbonates from other mineral classes. The acid reacts with the carbonate ([CO3]2-) group, which causes the affected area to effervesce, giving off carbon dioxide gas. This test can be further expanded to test the mineral in its original crystal form or powdered. An example of this test is done when distinguish calcite from dolomite, especially within rocks (limestone and dolostone respectively). Calcite immediately effervesces in acid, whereas acid must be applied to powdered dolomite (often to a scratched surface in a rock), for it to effervesce. Zeolite minerals will not effervesce in acid; instead, they become frosted after 5–10 minutes, and if left in acid for a day, they dissolve or become a silica gel. When tested, magnetism is a very conspicuous property of minerals. Among common minerals, magnetite exhibits this property strongly, and it is also present, albeit not as strongly, in pyrrhotite and ilmenite. Minerals can also be tested for taste or smell. Halite, NaCl, is table salt; its potassium-bearing counterpart, sylvite, has a pronounced bitter taste. Sulfides have a characteristic smell, especially as samples are fractured, reacting, or powdered.  Radioactivity is a rare property; minerals may be composed of radioactive elements. They could be a defining constituent, such as uranium in uraninite, autunite, and carnotite, or as trace impurities. In the latter case, the decay of a radioactive element damages the mineral crystal; the result, termed a radioactive halo or pleochroic halo, is observable by various techniques, such as thin-section petrography. Mineral classes As the composition of the Earth's crust is dominated by silicon and oxygen, silicate elements are by far the most important class of minerals in terms of rock formation and diversity. However, non-silicate minerals are of great economic importance, especially as ores. Non-silicate minerals are subdivided into several other classes by their dominant chemistry, which included native elements, sulfides, halides, oxides and hydroxides, carbonates and nitrates, borates, sulfates, phosphates, and organic compounds. The majority of non-silicate mineral species are extremely rare (constituting in total 8% of the Earth's crust), although some are relative common, such as calcite, pyrite, magnetite, and hematite. There are two major structural styles observed in non-silicates: close-packing and silicate-like linked tetrahedra. The close-packed structures, which is a way to densely pack atoms while minimizing interstitial space. Hexagonal close-packing involves stacking layers where every other layer is the same ("ababab"), whereas cubic close-packing involves stacking groups of three layers ("abcabcabc"). Analogues to linked silica tetrahedra include SO4 (sulfate), PO4 (phosphate), AsO4 (arsenate), and VO4(vanadate). The nonYoung Ji International School / College
Page 51
silicates have great economic importance, as they concentrate elements more than the silicate minerals do. The largest grouping of minerals by far are the silicates; most rocks are composed of greater than 95% silicate minerals, and over 90% of the Earth's crust is composed of these minerals. The two main constituents of silicates are silicon and oxygen, which are the two most abundant elements in the Earth's crust. Other common elements in silicate minerals correspond to other common elements in the Earth's crust, such aluminum, magnesium, iron, calcium, sodium, and potassium. Some important rock-forming silicates include the feldspars, quartz, olivines, pyroxenes, amphiboles,garnets, and micas. Silicate minerals
Aegirine, an iron-sodium clinopyroxene, is part of the inosilicate subclass. The base of unit of a silicate mineral is the [SiO 4]4- tetrahedron. In the vast majority of cases, silicon is in four-fold or tetrahedral coordination with oxygen. In very high-pressure situations, silicon will be six-fold or octahedral coordination, such as in the perovskite structure or the quartz polymorph stishovite (SiO2). In the latter case, the mineral no longer has a silicate structure, but that of rutile(TiO2), and its associated group, which are simple oxides. These silica tetrahedra are then polymerized to some degree to create various structures, such as one-dimensional chains, two-dimensional sheets, and three-dimensional frameworks. The basic silicate mineral where no polymerization of the tetrahedra has occurred requires other elements to balance out the base 4- charge. In other silicate structures, different combinations of elements are required to balance out the resultant negative charge. It is common for the Si4+ to be substituted by Al3+because of similarity in ionic radius and charge; in those case, the [AlO4]5-tetrahedra form the same structures as do the unsubstituted tetrahedra, but their charge-balancing requirements are different.
Young Ji International School / College
Page 52
The degree of polymerization can be described by both the structure formed and how many tetrahedral corners (or coordinating oxygens) are shared (for aluminium and silicon in tetrahedral sites). Orthosilicates (or nesosilicates) have no linking of polyhedra, thus tetrahedra share no corners. Disilicates (or sorosilicates) have two tetrahedra sharing one oxygen atom. Inosilicates are chain silicates; singlechain silicates have two shared corners, whereas double-chain silicates have two or three shared corners. In phyllosilicates, a sheet structure is formed which requires three shared oxygens; in the case of double-chain silicates, some tetrahedra must share two corners instead of three as otherwise a sheet structure would result. Framework silicates, or tectosilicates, have tetrahedra that share all four corners. The ring silicates, or cyclosilicates, only need tetrahedra to share two corners to form the cyclical structure. The silicate subclasses are described below in order of decreasing polymerization. Tectosilicates
Natrolite is a mineral series in the zeolite group; this sample has a very prominent acicular crystal habit. Tectosilicates, also known as framework silicates, have the highest degree of polymerization. With all corners of a tetrahedra shared, the silicon:oxygen ratio becomes 1:2. Examples are quartz, the feldspars,feldspathoids, and the zeolites. Framework silicates tend to be particularly chemically stable as a result of strong covalent bonds. Forming 12% of the Earth's crust, quartz (SiO2) is the most abundant mineral species. It is characterized by its high chemical and physical resistivity. Quartz has several polymorphs, including tridymite and cristobalite at high temperatures, highpressure coesite, and ultra-high pressure stishovite. The latter mineral can only be formed on Earth by meteorite impacts, and its structure has been composed so much that it had changed from a silicate structure to that of rutile(TiO2). The silica polymorph that is most stable at the Earth's surface is α-quartz. Its counterpart, βquartz, is present only at high temperatures and pressures (changes to α-quartz below 573 °C at 1 bar). These two polymorphs differ by a "kinking" of bonds; this Young Ji International School / College
Page 53
change in structure gives β-quartz greater symmetry than α-quartz, and they are thus also called high quartz (β) and low quartz (α). Phyllosilicates
Muscovite, a mineral species in the mica group, within the phyllosilicate subclass Phyllosilicates consist of sheets of polymerized tetrahedra. They are bound at three oxygen sites, which gives a characteristic silicon:oxygen ratio of 2:5. Important examples include the mica,chlorite, and the kaolinite-serpentine groups. The sheets are weakly bound by van der Waals forces or hydrogen bonds, which causes a crystallographic weakness, in turn leading to a prominent basal cleavage among the phyllosilicates. In addition to the tetrahedra, phyllosilicates have a sheet of octahedra (elements in six-fold coordination by oxygen) that balanced out the basic tetrahedra, which have a negative charge (e.g. [Si4O10]4-) These tetrahedra (T) and octahedra (O) sheets are stacked in a variety of combinations to create phyllosilicate groups. Within an octahedral sheet, there are three octahedral sites in a unit structure; however, not all of the sites may be occupied. In that case, the mineral is termed dioctahedral, whereas in other case it is termed trioctahedral. Understanding Concepts Complete each sentence 1. Halite forms _____ crystals. 2. ____________ contain the two most abundant elements in earth‘s crust. 3. The mineral ___________ is harder than apatite and softer than quartz. 4. Diamonds and cool are both made of ______. 5. ________ have a definite volume and shape. Think and Write Critically 1. What‘s the difference between an ore and a gem? 2. Describe the dangers of asbestos fibers. 3. Explain why air is not a mineral? Young Ji International School / College
Page 54
4. Compare and contracts the properties of cleavage and fracture. List an example of a mineral that cleaves and one that fractures. 5. Why is asbestos removal a controversy/
1.
2. 3. 4.
Apply Water is nonliving substance formed by natural processes on earth. It has a unique composition. Sometimes water is a mineral and other time it is not. Explain. How many sides are there to perfect salt crystals? Suppose you let a sugar solution evaporates, leaving sugar crystals behind. Are these crystals minerals? Explain. Will diamond leave a streak on a streak plate? Explain.
Chapter 5
Rock
What is a rock? A rock is a mixture of minerals. The rock cycle is a basic concept in geology that describes the dynamic transitions through geologic time among the three main rock types: sedimentary, metamorphic, and igneous. As the diagram to the right illustrates, each of the types of rocks is altered or destroyed when it is forced out of its equilibrium conditions. An igneous rock such as basalt may break down and dissolve when exposed to the atmosphere, or melt as it is sub ducted under a continent. Due to the driving forces of the rock cycle, plate tectonics and the water cycle, rocks do not remain in equilibrium and are forced to change as they encounter new environments. The rock cycle is an illustration that explains how the three rock types is related to each other, and how processes change from one type to another over time.
A diagram of the rock cycle. Legend: 1 = magma; 2 = crystallization (freezing of rock); 3 = igneous rocks; 4 = erosion; 5 = sedimentation; 6 Young Ji International School / College
Page 55
= sediments &sedimentary rocks; 7 = tectonic burial and metamorphism; 8 = metamorphic rocks; 9 = melting.
The Rock cycle
Structures of Igneous Rock. Legend: A = magma chamber (batholith); B = dyke/dike; C = laccolith; D =pegmatite; E = sill; F = stratovolcano; processes: 1 = newer intrusion cutting through older one; 2 = xenolith or roof pendant; 3 = contact metamorphism; 4 = uplift due to laccolith emplacement. Transition to igneous When rocks are pushed deep under the Earth's surface, they may melt into magma. If the conditions no longer exist for the magma to stay in its liquid state, it will cool and solidify into an igneous rock. A rock that cools within the Earth is called intrusive or plutonic and will cool very slowly, producing a coarse-grained texture. As a result of volcanic activity, magma (which is called lava when it reaches Earth's surface) may cool very rapidly while being on the Earth's surface exposed to the atmosphere and are called extrusive or volcanic rocks. These rocks are finegrained and sometimes cool so rapidly that no crystals can form and result in a natural glass, such as obsidian. Any of the three main types of rocks (igneous, sedimentary, and metamorphic rocks) can melt into magma and cool into igneous rocks. Secondary changes Epigenetic change (secondary processes) may be arranged under a number of headings, each of which is typical of a group of rocks or rock-forming minerals, though usually more than one of these alterations will be found in progress in the same rock. Silicification, the replacement of the minerals by crystalline or cryptocrystalline silica, is most common in felsic rocks, such as rhyolite, but is also found in serpentine, etc. Kaolinization is the decomposition of the feldspars, which are the most common minerals in igneous rocks, into kaolin (along with quartz and other clay minerals); it is best shown by granites and syenites. Serpentinization is the alteration of olivine to serpentine (with magnetite); it is typical of peridotites, but occurs in most of the mafic rocks. In uralitization secondary hornblende replaces augite; this occurs very generally Young Ji International School / College
Page 56
indiabases; chloritization is the alteration of augite (biotite or hornblende) to chlorite, and is seen in many diabases, dioritesand greenstones. Epidotization occurs also in rocks of this group, and consists in the development of epidote from biotite, hornblende, augite or plagioclase feldspar. Concept Review 1. How do igneous rocks form? 2. Which type of magma and lava form igneous rocks that are dark colored and dense? 3. How do intrusive and extrusive igneous rocks differ/ 4. Apply: How are granite and rhyolite similar? How are they different? Transition to metamorphic
This diamond is a mineral from within an igneous or metamorphic rock that formed at high temperature and pressure. Rocks exposed to high temperatures and pressures can be changed physically or chemically to form a different rock, called metamorphic. Regional metamorphism refers to the effects on large masses of rocks over a wide area, typically associated with mountain building events within organic belts. These rocks commonly exhibit distinct bands of differing mineralogy and colors, called foliation. Another main type of metamorphism is caused when a body of rock comes into contact with an igneous intrusion that heat up this surrounding country rock. This contact metamorphism results in a rock that is altered and recrystallized by the extreme heat of the magma and/or by the addition of fluids from the magma that add chemicals to the surrounding rock (metasomatism). Any preexisting type of rock can be modified by the processes of metamorphism. Transition to sedimentary Rocks exposed to the atmosphere are variably unstable and subject to the processes of weathering and erosion. Weathering and erosion break the original rock down into smaller fragments and carry away dissolved material. This fragmented material accumulates and is buried by additional material. While an individual grain of sand is still a member of the class of rock it was formed from, a rock made up of such grains fused together is sedimentary. Sedimentary rocks can be formed from the lithification of these buried smaller fragments Young Ji International School / College
Page 57
(clastic sedimentary rock), the accumulation and lithification of material generated by living organisms (biogenic sedimentary rock - fossils), or lithification of chemically precipitated material from a mineral bearing solution due to evaporation (precipitate sedimentary rock). Clastic rocks can be formed from fragments broken apart from larger rocks of any type, due to processes such as erosion or from organic material, like plant remains. Biogenic and precipitate rocks form from the deposition of minerals from chemicals dissolved from all other rock types. Origin of Sedimentary Rocks Most of the rocks below earth‘s surface are igneous rocks. Igneous rocks are the most common rocks on earth. But chances are, you‘ve seen more sedimentary rocks than igneous rocks. Seventy-five percent of the rocks at Earth‘s surface are sedimentary rocks. Sedimentary rocks form when sediments become pressed or cemented together or when sediments fall out of solution. Sediments are loose materials such as rock fragments, minerals grains, and bits of plant and animal remains that have been transported. Weathering is the process that breaks rocks into smaller pieces. Concept Review 1. What type of mine removes coal by removing overlying vegetation, soil, and rock? 2. List two environmental problems caused by underground mining.
1. 2. 3. 4. 5.
Think and write critically Explain why the rock cycle has no beginning and no end. Compare magma and lava. Compare and contrast classic rocks with organic and chemical rocks. How do strip mines harm wildlife? List the steps from first to last that a mining company would have to take to reclaim an area that was strip mined.
Chapter 6
Plate tectonics
Spreading ridges The start of boundaries where
the cycle can be placed at the mid-ocean divergent new magma is produced by mantle upwelling and a
Young Ji International School / College
Page 58
shallow melting zone. This new or juvenile basaltic magma is the first phase of the igneous portion of the cycle. It should be noted that the least dense magma phases tend to be favored in eruptions. As the ridge spreads and the new rock is carried away from the ridge, the interaction of heated circulating seawater through crevices starts the initial retrograde metamorphism of the new rock. Subduction zones
The Juan de Fuca plate sinks below the North America plate at the Cascadia subduction zone. Subduction The new basaltic oceanic crust eventually meets a subduction zone as it moves away from the spreading ridge. As this crust is pulled back into the mantle, the increasing pressure and temperature conditions cause a restructuring of the mineralogy of the rock, this metamorphism alters the rock to form eclogite. As the slab of basaltic crust and some included sediments are dragged deeper, water and other more volatile materials are driven off and rise into the overlying wedge of rock above the subduction zone which is at a lower pressure. The lower pressure, high temperature, and now volatile rich material in this wedge melts and the resulting buoyant magma rises through the overlying rock to produce island arc or continental marginvolcanism. This volcanism includes more silicic lavas the further from the edge of the island arc or continental margin, indicating a deeper source and a more differentiated magma. At times some of the metamorphosed down going slab may be thrust up or obducted onto the continental margin. These blocks of mantle peridotite and the metamorphic eclogites are exposed as ophiolite complexes. The newly erupted volcanic material is subject to rapid erosion depending on the climate conditions. These sediments accumulate within the basins on either side of an island arc. As the sediments become more deeply buried lithification begins and sedimentary rock results. Continental collision On the closing phase of the classic Wilson cycle, two continental or smaller terrenes meet at a convergent zone. As the two masses of continental crust meet, Young Ji International School / College
Page 59
neither can be subducted as they are both low density silicic rock. As the two masses meet, tremendous compression forces distort and modify the rocks involved. The result is regional metamorphism within the interior of the ensuing orogeny or mountain building event. As the two masses are compressed, folded and faulted into a mountain range by the continental collision the whole suite of pre-existing igneous, volcanic, sedimentary and earlier metamorphic rock units are subjected to this new metamorphic event. Accelerated erosion The high mountain ranges produced by continental collisions are immediately subjected to the forces of erosion. Erosion wears down the mountains and massive piles of sediment are developed in adjacent ocean margins, shallow seas, and as continental deposits. As these sediment piles are buried deeper they become lithified into sedimentary rock. The metamorphic, igneous, and sedimentary rocks of the mountains become the new piles of sediments in the adjoining basins and eventually become sedimentary rock. An evolving process The plate tectonics rock cycle is an evolutionary process. Magma generation, both in the spreading ridge environment and within the wedge above a subduction zone, favors the eruption of the more silicic and volatile rich fraction of the crustal or upper mantle material. This lower density material tends to stay within the crust and not be subducted back into the mantle. The magmatic aspect of plate tectonics tends to gradual segregation within or between the mantle and crust. As magma forms, the initial melt is composed of the more silicic phases that have a lower melting point. This leads to partial melting and further segregation of the lithosphere. In addition the silicic continental crust is relatively buoyant and is not normally subducted back into the mantle. So over time the continental masses grow larger and larger. The role of water Water cycle The presence of abundant water on Earth is of great importance for the rock cycle. Most obvious perhaps are the water driven processes of weathering and erosion. Water in the form of precipitation and acidic soil water and groundwater is quite effective at dissolving minerals and rocks, especially those igneous and metamorphic rocks and marine sedimentary rocks that are unstable under near surface and atmospheric conditions. The water carries away the ions dissolved in solution and the broken down fragments that are the products of weathering. Running water carries vast amounts of sediment in rivers back to the ocean and inland basins. The accumulated and buried sediments are converted back into rock. Weathering and soil Weathering is the breaking down of rocks, soil and minerals as well as artificial materials through contact with the atmosphere, biota and waters. Young Ji International School / College
Page 60
Weathering occurs in situ, roughly translated to: "with no movement" , and thus should not be confused with erosion, which involves the movement of rocks and minerals by agents such as water, ice, snow, wind, waves and gravity and then being transported and deposited in other locations. Two important classifications of weathering processes exist – physical and chemical weathering; each sometimes involves a biological component. Mechanical or physical weathering involves the breakdown of rocks and soils through direct contact with atmospheric conditions, such as heat, water, ice and pressure.  The second classification, chemical weathering, involves the direct effect of atmospheric chemicals or biologically produced chemicals also known as biological weathering in the breakdown of rocks, soils and minerals. While physical weathering is accentuated in very cold or very dry environments, chemical reactions are most intense where the climate is wet and hot. However, both types of weathering occur together, and each tends to accelerate the other. For example, physical abrasion (rubbing together) decreases the size of particles and therefore increases their surface area, making them more susceptible to rapid chemical reactions. The various agents act in concert to convert primary minerals (feldspars and micas) to secondary minerals (clays and carbonates) and release plant nutrient elements in soluble forms. The materials left over after the rock breaks down combined with organic material creates soil. The mineral content of the soil is determined by the parent material, thus a soil derived from a single rock type can often be deficient in one or more minerals for good fertility, while a soil weathered from a mix of rock types (as in glacial, aeolian or alluvial sediments) often makes more fertile soil. In addition, many of Earth's landforms and landscapes are the result of weathering processes combined with erosion and re-deposition. Soil Soil is the mixture of minerals, organic matter, gases, liquids, and the myriad of organisms that together support plant life. It is a natural body that exists as part of the pedosphere and which performs four important functions: it is a medium for plant growth; it is a means of water storage, supply and purification; it is a modifier of the atmosphere; and it is a habitat for organisms that take part in decomposition of organic matter and the creation of a habitat for new organisms. Soil is considered to be the "skin of the earth" with interfaces between the lithosphere, hydrosphere, atmosphere, and biosphere. Soil consists of a solid phase (minerals and organic matter) as well as a porous phase that holds gases and water. Accordingly, soils are often treated as a three-state system. Soil is the end product of the influence of the climate, relief (elevation, orientation, and slope of terrain), biotic activities (organisms), and parent materials (original minerals) interacting over time. Soil continually undergoes development by Young Ji International School / College
Page 61
way of numerous physical, chemical and biological processes, which include weathering with associated erosion. Most soils have a density between 1 and 2 g/cm3. Little of the soil of planet Earth is older than the Pleistocene and none is older than the Cenozoic, although fossilized soils are preserved from as far back as the Archean. Soil science has two main branches of study: Edaphology and Pedology. Pedology is focused on the formation, description (morphology), and classification of soils in their natural environment, whereas edaphology is concerned with the influence of soils on organisms. In engineering terms, soil is referred to as regolith, or loose rock material that lies above the 'solid geology'. Soil is commonly referred to as "earth" or "dirt"; technically, the term "dirt" should be restricted to displaced soil. As soil resources serve as a basis for food security, the international community advocates for its sustainable and responsible use through different types of Soil Governance.
A represents soil; A regolith B represents laterite,; C represents saprolite, a less-weathered regolith; the bottom-most layer represents bedrock Erosion and deposition Water supply is the provision of water by public utilities, commercial organizations, community endeavors or by individuals, usually via a system of pumps and pipes. Irrigation is covered separately. Air Weather is the condition of the atmosphere at a particular place over a short period of time. For example, on a particular day in Trinidad, the weather is warm in the afternoon. But later in the day, when there are clouds blocking Sun's rays, the weather would become cooler. Climate refers to the weather pattern of a place over a long period, maybe 30 years or more, long enough to yield meaningful averages. For example, although the weather in Pakistan may be cool and dry today, Pakistan's climate is hot most of the time. Young Ji International School / College
Page 62
Meteorology studies weather, while Climatology studies climate. Both are Atmospheric sciences, and indeed, several university departments are named in this manner to avoid division.
Elements There are several elements that make up the weather and climate of a place. The major of these elements are five: temperature, pressure, wind, humidity, and rain. Analysis of these elements can provide the basis for forecasting weather and defining its climate. These same elements make also the basis of climatology study; of course, within a longer time scale rather than it does in meteorology. Temperature is how hot or cold the atmosphere is, how many degrees it is above or below freezing. Temperature is a very important factor in determining the weather, because it influences or controls other elements of the weather, such as precipitation, humidity, clouds and atmospheric pressure. Humidity is the amount of water vapor in the atmosphere. Precipitation is the product of a rapid condensation process (if this process is slow, it only causes cloudy skies). It may include snow, hail, sleet, drizzle, fog, mist and rain. Atmospheric pressure (or air pressure) is the weight of air resting on the earth's surface. Pressure is shown on a weather map, often called a synoptic map, with lines called isobars. Wind is the movement of air masses, especially on the Earth's surface. Modifying factors The more important are also five: latitude, altitude, distance to the ocean and/ or sea, orientation of mountain ranges toward prevailing winds and ocean currents. Climate change is a change in the statistical distribution of weather patterns when that change lasts for an extended period of time (i.e., decades to millions of years). Climate change may refer to a change in average weather conditions, or in the time variation of weather around longer-term average conditions (i.e., more or fewer extreme weather events). Climate change is caused by factors such as biotic processes, variations in solar radiation received by Earth, plate tectonics, and volcanic eruptions. Certain human activities have also been identified as significant causes of recent climate change, often referred to as "global warming". Terminology The most general definition of climate change is a change in the statistical properties of the climate system when considered over long periods of time, regardless of cause. Accordingly, fluctuations over periods shorter than a few decades, such as El Niño, do not represent climate change.
Young Ji International School / College
Page 63
The term sometimes is used to refer specifically to climate change caused by human activity, as opposed to changes in climate that may have resulted as part of Earth's natural processes. In this sense, especially in the context of environmental policy, the term climate change has become synonymous with anthropogenic global warming. Within scientific journals, global warming refers to surface temperature increases while climate change includes global warming and everything else that increasing greenhouse gas levels will affect.  Causes On the broadest scale, the rate at which energy is received from the sun and the rate at which it is lost to space determine the equilibrium temperature and climate of Earth. This energy is distributed around the globe by winds, ocean currents, and other mechanisms to affect the climates of different regions. Factors that can shape climate are called climate forcings or "forcing mechanisms‖. These include processes such as variations in solar radiation, variations in the Earth's orbit, variations in the albedo or reflectivity of the continents and oceans, mountain-building and continental drift and changes in greenhouse gas concentrations. There are a variety of climate change feedbacks that can either amplify or diminish the initial forcing. Some parts of the climate system, such as the oceans and ice caps, respond more slowly in reaction to climate forcings, while others respond more quickly. There are also key threshold factors which when exceeded can produce rapid change. Forcing mechanisms can be either "internal" or "external". Internal forcing mechanisms are natural processes within the climate system itself (e.g., the thermohaline circulation). External forcing mechanisms can be either natural (e.g., changes in solar output) or anthropogenic (e.g., increased emissions of greenhouse gases). Whether the initial forcing mechanism is internal or external, the response of the climate system might be fast (e.g., a sudden cooling due to airborne volcanic ash reflecting sunlight), slow (e.g. thermal expansion of warming ocean water), or a combination (e.g., sudden loss of albedo in the arctic ocean as sea ice melts, followed by more gradual thermal expansion of the water). Therefore, the climate system can respond abruptly, but the full response to forcing mechanisms might not be fully developed for centuries or even longer.  Internal forcing mechanisms Scientists generally define the five components of earth's climate system to include atmosphere, hydrosphere,cryosphere, lithosphere (restricted to the surface soils, rocks, and sediments), and biosphere. Natural changes in the climate system ("internal forcings") result in internal "climate variability". Examples include the type and distribution of species, and changes in ocean currents.
Young Ji International School / College
Page 64
Ocean variability
Pacific Decadal Oscillation 1925 to 2010 The ocean is a fundamental part of the climate system, some changes in it occurring at longer timescales than in the atmosphere, massing hundreds of times more and having very high thermal inertia (such as the ocean depths still lagging today in temperature adjustment from the Little Ice Age). Short-term fluctuations (years to a few decades) such as the El NiĂąo-Southern Oscillation, the Pacific decadal oscillation, the North Atlantic oscillation, and the Arctic oscillation, represent climate variability rather than climate change. On longer time scales, alterations to ocean processes such as thermohaline circulation play a key role in redistributing heat by carrying out a very slow and extremely deep movement of water and the long-term redistribution of heat in the world's oceans.
A schematic of modern thermohaline circulation. Tens of millions of years ago, continental plate movement formed a land-free gap around Antarctica, allowing formation of the ACC which keeps warm waters away from Antarctica.  Life Life affects climate through its role in the carbon and water cycles and such mechanisms as albedo, evapotranspiration, cloud formation, and weathering. Examples of how life may have affected past climate include: glaciations 2.3 billion years ago triggered by the evolution of oxygenic photosynthesis, glaciations 300 million years ago ushered in by long-term burial of decompositionresistant detritus of vascular land plants (forming coal), termination of the Paleocene-Eocene Thermal Maximum 55 million years ago by flourishing marine phytoplankton, reversal of global warming 49 million years ago by 800,000 years of arctic azolla blooms, and global cooling over the past 40 million years driven by the expansion of grass-grazer ecosystems. Climate science in recent decades has seen an increasing rate of advancement, particularly in field research and notably through the evolution of measuring climate change methodology and tools, including the models and Young Ji International School / College
Page 65
observations that support and enable the research. During the last four decades, the rate at which scientists have added to the body of knowledge of atmospheric and oceanic processes has accelerated dramatically. As scientists incrementally increase the totality of knowledge, they publish their results in peer-reviewed journals. Instruments Used When Measuring Climate Change There are a number of key factors in measuring climate change, and they are broadly categorized below. The range of instrumentation used to observe and measure climate is truly amazing. By following the links below you can see the types of instruments, and where they are used. Temperature When measuring climate change this is a primary and can be measured or reconstructed for the Earth‘s surface, and sea surface temperature (SST). Precipitation (rainfall, snowfall etc) offers another indicator of relative climate variation and may include humidity or water balance, and water quality. Biomass and vegetation patterns may be discerned in a variety of ways and provide evidence of how ecosystems change to adapt to climate change. Sea Level measurements reflect changes in shoreline and usually relate to the degree of ice coverage in high latitudes and elevations. Solar Activity can influence climate, primarily through changes in the intensity of solar radiation. Volcanic Eruptions, like solar radiation, can alter climate due to the aerosols that are emitted into the atmosphere and alter climate patterns. Chemical composition of air or water can be measured by tracking levels of greenhouse gases such as carbon dioxide and methane, and measuring ratios of oxygen isotopes. Research indicates a strong correlation between the percent of carbon dioxide in the atmosphere and the Earth‘s mean temperature. In understanding global climate changes it is necessary to combine many disciplines, including oceanography, meteorology, geomorphology, geology and paleoclimatology. As well as combining interdisciplinary studies, observations and measurements can be assembled over long time spans, using different measuring approaches. For example, the annual averages of the global mean sea level seen below are based on reconstructed sea level fields since 1870 (red), and the tide gauge measurements are since 1950 (blue) while the satellite altimetry is since 1992 (black). The units are in millimetres relative to the average for 1961 to 1990 and the error bars are at 90% confidence intervals. Young Ji International School / College
Page 66
By combining these three different approaches, scientists are able to build a clear picture of rising sea level that would not be possible if each was presented independently. You can also see with the introduction of accurate measuring, the confidence level for accuracy increases.
How Climate Knowledge Accumulates Despite occasional major paradigm shifts, the majority of scientific insights, even unexpected insights, tend to emerge incrementally as a result of repeated attempts to test hypotheses as thoroughly as possible. Therefore, because almost every new advance is based on the research and understanding that has gone before, science is cumulative, with useful features retained and non-useful features abandoned. Active research scientists, throughout their careers, typically spend large fractions of their working time studying in depth what other scientists have done. Superficial or amateurish acquaintance with the current state of a scientific research topic is an obstacle to a scientist‘s progress. Working scientists know that a day in the library can save a year in the laboratory when measuring climate change. Good science questions competing assertions about climate change. For example, can the statement under consideration, in principle, be proven false? Has it been rigorously tested? Did it appear in the peer-reviewed literature? Did it build on the existing research record where appropriate? If the answer to any of these questions is no, then less credence should be given to the assertion until it is tested and independently verified. Young Ji International School / College
Page 67
Uncertainties in Measuring Climate Change The history of the centuries-long effort to document and understand climate change is often complex, marked by successes and failures, and has followed a very uneven pace. Testing scientific findings and openly discussing the test results have been the key to the remarkable progress that is now accelerating in all domains, in spite of inherent limitations to predictive capacity. Climate change science is now contributing to the foundation of a new interdisciplinary approach to understanding our environment. Consequently, much published research and many notable scientific advances have occurred in the last few decades, including advances in the understanding and treatment of uncertainty. Uncertainties can be classified in several different ways according to their origin. Two primary types are ‗value uncertainties‘ and ‗structural uncertainties‘. Value uncertainties arise from the incomplete determination of particular values or results, for example, when data are inaccurate or not fully representative of the phenomenon of interest. Structural uncertainties arise from an incomplete understanding of the processes that control particular values or results, for example, when the conceptual framework or model used for analysis does not include all the relevant processes or relationships. Uncertainties associated with ‗random errors‘ have the characteristic of decreasing as additional measurements are accumulated, whereas those associated with ‗systematic errors‘ do not. In dealing with climate records, scientists give considerable attention to the identification of systematic errors or unintended biases arising from data sampling issues and methods of analyzing and combining data. Fortunately, science is inherently self-correcting; incorrect or incomplete scientific concepts ultimately do not survive repeated testing against observations of nature. Tectonic–climatic interaction refers to Earth's natural climatic and tectonic processes and the potential influences exerted on each other. The geologic processes include orogenesis, volcanism, and erosion and the climatic processes include atmospheric circulation, orographic lift, monsoon circulation and the rain shadow effect. Geological processes are rarely instantaneous and thus workers are limited to what they observe in the earth's natural record. As is common in geology, these constraints have led to different schools of thought and questions regarding the interactions between climate and tectonics mainly is climate the cause of terrain uplift or is it tectonism that causes changes in the climate? Support for both theories is included in this article as well as investigations of major mountain ranges and respective climates. Orographic controls on climate Depending on the vertical and horizontal magnitude of a mountain range, it has the potential to have strong effects on global and regional climate patterns and processes including: deflection of atmospheric circulation, creation of orographic lift, altering monsoon circulation, and causing the rain shadow effect. Young Ji International School / College
Page 68
Simple illustration of the rain shadow effect One well known example of an elevated terrain and its effect on climate occurs in the Southeast Asian Himalayas, the world's highest mountain system. A range of this size has the ability to influence geographic temperature, precipitation, and wind. Theories suggest that the uplift of the Tibetan Plateau has resulted in stronger deflections of the atmospheric jet stream, a heavier monsoonal circulation, increased rainfall on the front slopes, greater rates of chemical weathering, and thus lower atmospheric CO2 concentrations. It is possible that the spatial magnitude of this range is so great that it creates a regional monsoon circulation in addition to disrupting hemispheric-scale atmospheric circulation.
Example of the rain shadow effect in the Himalayas The monsoon season in Southeast Asia occurs due to the Asian continent becoming warmer than the surrounding oceans during the summer; as a lowpressure cell is created above the continents, a high-pressure cell forms over the cooler ocean, causing advection of moist air, creating heavy precipitation from Africa to Southeast Asia. However, the intensity of the rainfall over Southeast Asia is greater than the African monsoon, which can be attributed to the awesome size of the Asian continent compared to the African continent and the presence of a vast mountain system. This not only affects the climate of Southeast Asia, but modifies the climate in neighboring areas such as Siberia, central Asia, the Middle East, and the Mediterranean basin as well. To test this model was created that changed only the topography of current landmasses, which resulted in correlations between the model and global fluctuations in precipitation and temperature over the past 40 Myr. Interpreted by scientists. It is commonly agreed upon that global climate fluctuations are strongly dictated by the presence or absence of greenhouse gases in the atmosphere and carbon dioxide (CO2) is typically considered the most significant greenhouse gas. Observations infer that large uplifts of mountain ranges globally result in higher chemical erosion rates, thus lowering the volume of CO2 in the atmosphere as well as causing global cooling.[2] This occurs because in regions of higher elevation there
Young Ji International School / College
Page 69
are higher rates of mechanical erosion (i.e. gravity, fluvial processes) and there is constant exposure and availability of materials available for chemical weathering. The following is a simplified equation describing the consumption of CO2 during chemical weathering of silicates: CaSiO3 + CO2 ↔ CaCO3 + SiO2 From this equation, it is inferred that carbon dioxide is consumed during chemical weathering and thus lower concentrations of the gas will be present in the atmosphere as long as chemical weathering rates are high enough. Climate-driven tectonism There are scientists who reject that uplift is the sole cause of climate change and are in favor of uplift as a result of climate change. Some geologists theorize that a cooler and stormier climate (such as glaciations and increased precipitation) can give a landscape a younger appearance such as incision of high terrains and increased erosion rates. Glaciers are a powerful eroding agent with the ability to incise and carve deep valleys and when rapid erosion of the earth's surface occurs, especially in an area of limited relief, it is possible for isocratic rebound to occur, creating high peaks and deep valleys. A lack of glaciations or precipitation can cause an increase in erosion, but can vary between localities. It is possible to create erosion in the absence of precipitation because there would be a decrease in vegetation, which typically acts as a protective cover for the bedrock.
Peaks and valleys of the Torres del Paine range of the Andes in Chile Models also suggest that certain topographic features of the Himalayan and Andes region is determined by an erosion/climatic interaction as opposed to tectonics. These models reveal a correlation between regional precipitation and a maximum topographic limit at the plateau margin. In the southern Andes where there is relatively low precipitation and denudation rates, there is no real extreme topography present at the plateau margin while in the north there are higher rates of precipitation and the presence of extreme topography. Another interesting theory comes from an investigation of the uplift of the Andes during the Cenozoic. Some scientists hypothesize that the tectonic processes of plate subduction and mountain building are products of erosion and sedimentation. When there is an arid climate influenced by the rain shadow effect in a mountainous region, sediment supply to the trench can be reduced or even cut off. These sediments are thought to act as lubricants at the plate interface and this Young Ji International School / College
Page 70
reduction increases the shear stress present at the interface that is large enough to support the high Andes. Volcanism Around the world, dotting the map are volcanoes of all shapes and sizes. Lining the landmass around the Pacific Ocean are the well-known volcanoes of the Pacific Ring of Fire. From the Aleutian Islands to the Andes Mountains in Chile, these volcanoes have sculpted their local and regional environments. Aside from admiring their majestic beauty, one might wonder how these geologic wonders work and what role they play in changing the landscape and atmosphere. Principally, volcanoes are geologic features that exude magmatic material from below Earth's surface onto the surface. Upon reaching the surface, the term "magma" disappears and "lava" becomes the common nomenclature. This lava cools and forms igneous rock. By examining igneous rocks, it is possible to derive a chain of events that led from the original melt of the magma to the crystallization of the lava at Earth's surface. By examining igneous rocks, it is possible to postulate evidence for volcanic out gassing, which is known to alter atmospheric chemistry. This alteration of atmospheric chemistry changes climate cycles both globally and locally. Greenhouse effect
A representation of the exchanges of energy between the source (the Sun), the Earth's surface, the Earth's atmosphere, and the ultimate sink outer space. The ability of the atmosphere to capture and recycle energy emitted by the Earth surface is the defining characteristic of the greenhouse effect.
Another diagram of the greenhouse effect The greenhouse effect is a process by which thermal radiation from a planetary surface is absorbed by atmospheric greenhouse gases, and is re-radiated in all directions. Since part of this re-radiation is back towards the surface and the Young Ji International School / College
Page 71
lower atmosphere, it results in an elevation of the average surface temperature above what it would be in the absence of the gases. Solar radiation at the frequencies of visible light largely passes through the atmosphere to warm the planetary surface, which then emits this energy at the lower frequencies of infrared thermal radiation. Infrared radiation is absorbed by greenhouse gases, which in turn re-radiate much of the energy to the surface and lower atmosphere. The mechanism is named after the effect of solar radiation passing through glass and warming a greenhouse, but the way it retains heat is fundamentally different as a greenhouse works by reducing airflow, isolating the warm air inside the structure so that heat is not lost by convection. If an ideal thermally conductive blackbody were the same distance from the Sun as the Earth is, it would have a temperature of about 5.3 °C. However, since the Earth reflects about 30%of the incoming sunlight, this idealized planet's effective temperature (the temperature of a black body that would emit the same amount of radiation) would be about −18 °C. The surface temperature of this hypothetical planet is 33 °C below Earth's actual surface temperature of approximately 14 °C. The mechanism that produces this difference between the actual surface temperature and the effective temperature is due to the atmosphere and is known as the greenhouse effect. Earth‘s natural greenhouse effect makes life as we know it possible. However, human activities, primarily the burning of fossil fuels and clearing of forests, have intensified the natural greenhouse effect, causing global warming. Mechanism The Earth receives energy from the Sun in the form UV, visible, and near IR radiation, most of which passes through the atmosphere without being absorbed. Of the total amount of energy available at the top of the atmosphere (TOA), about 50% is absorbed at the Earth's surface. Because it is warm, the surface radiates far IR thermal radiation that consists of wavelengths that are predominantly much longer than the wavelengths that were absorbed (the overlap between the incident solar spectrum and the terrestrial thermal spectrum is small enough to be neglected for most purposes). Most of this thermal radiation is absorbed by the atmosphere and re-radiated both upwards and downwards; that radiated downwards is absorbed by the Earth's surface. This trapping of long-wavelength thermal radiation leads to a higher equilibrium temperature than if the atmosphere were absent. This highly simplified picture of the basic mechanism needs to be qualified in a number of ways, none of which affect the fundamental process.
Young Ji International School / College
Page 72
The solar radiation spectrum for direct light at both the top of the Earth's atmosphere and at sea level
Synthetic stick absorption spectrum of a simple gas mixture corresponding to the Earth's atmosphere composition based on HITRAN data created using Hitran on the Web system. Green color - water vapor, red - carbon dioxide, WN - wave number (caution: lower wavelengths on the right, higher on the left). The incoming radiation from the Sun is mostly in the form of visible light and nearby wavelengths, largely in the range 0.2–4 μm, corresponding to the Sun's radiative temperature of 6,000 K. Almost half the radiation is in the form of "visible" light, which our eyes are adapted to use. About 50% of the Sun's energy is absorbed at the Earth's surface and the rest is reflected or absorbed by the atmosphere. The reflection of light back into space— largely by clouds—does not much affect the basic mechanism; this light, effectively, is lost to the system. The absorbed energy warms the surface. Simple presentations of the greenhouse effect, such as the idealized greenhouse model, show this heat being lost as thermal radiation. The reality is more complex: the atmosphere near the surface is largely opaque to thermal radiation (with important exceptions for "window" bands), and most heat loss from the surface is by sensible heat and latent heat transport. Radioactive energy losses become increasingly important higher in the atmosphere largely because of the decreasing concentration of water vapor, an important greenhouse gas. It is more realistic to think of the greenhouse effect as applying to a "surface" in the mid-troposphere, which is effectively coupled to the surface by a lapse rate. The simple picture assumes a steady state. In the real world there is the diurnal cycle as well as seasonal cycles and weather. Solar heating only applies during daytime. During the night, the atmosphere cools somewhat, but not greatly, Young Ji International School / College
Page 73
because its emissivity is low, and during the day the atmosphere warms. Diurnal temperature changes decrease with height in the atmosphere. Within the region where radiative effects are important the description given by the idealized greenhouse model becomes realistic: The surface of the Earth, warmed to a temperature around 255 K, radiates long-wavelength, infrared heat in the range 4–100 μm. At these wavelengths, greenhouse gases that were largely transparent to incoming solar radiation are more absorbent. Each layer of atmosphere with greenhouses gases absorbs some of the heat being radiated upwards from lower layers. It re-radiates in all directions, both upwards and downwards; in equilibrium (by definition) the same amount as it has absorbed. This results in more warmth below. Increasing the concentration of the gases increases the amount of absorption and re-radiation, and thereby further warms the layers and ultimately the surface below. Greenhouse gases—including most diatomic gases with two different atoms (such as carbon monoxide, CO) and all gases with three or more atoms—are able to absorb and emit infrared radiation. Though more than 99% of the dry atmosphere is IR transparent (because the main constituents—N2, O2, and Ar—are not able to directly absorb or emit infrared radiation), intermolecular collisions cause the energy absorbed and emitted by the greenhouse gases to be shared with the other, non-IRactive, gases. Key Terms 1. Plate tectonics 2. Pangaea 3. Laurisia 4. Lithosphere 5. Reversal 6. Isostasy 7. Supercontinent 8. Hot spot 9. Mantle plume 10. Convection 11. Subduction zone 12. Subduction 13. Continental rifting 14. Transform boundary 15. Plate boundary For Discussion 1. Discuss why a unifying theory, such as the plate tectonics theory, is desirable in any field of science. 2. Central Greenland lies below sea level because the crust is depressed by the ice cap. If the glacier were to melt, would Greenland remain beneath the ocean? Why or why not? 3. Describe the Mid-Oceanic Ridge. Young Ji International School / College
Page 74
4. Explain how sea-floor spreading supports the modern theory of plate tectonics. 5. Describe some important differences between oceanic crust and continental crust. 6. Describe and explain the important differences between the lithosphere and the asthenosphere.
Chapter 7:
The Solar System
List of natural satellites The Solar System's planets and officially recognized dwarf planets are known to be orbited by 180 natural satellites, or moons. 19 moons in the Solar System are large enough to have achieved hydrostatic equilibrium, and thus would be considered planets or dwarf planets if they were in direct orbit around the Sun. Moons are classed in two separate categories according to their orbits: regular moons, which have prograde orbits (they orbit in the direction of their planets' rotation) and lie close to the plane of their equators, and irregular moons, whose orbits can be pro- or retrograde (against the direction of their planets' rotation) and often lie at extreme angles to their planets' equators. Irregular moons are probably minor planets that have been captured from surrounding space. Most irregular moons are less than 10 kilometers (6.2 mi) in diameter. The earliest published discovery of a moon other than the Earth's was by Galileo Galilei, who discovered the four Galilean moons in 1610. Over the following three centuries only a few more moons were discovered. Missions to other planets in the 1970s, most notably the Voyager 1 and 2 missions, saw a surge in the number of moons detected, and observations since the year 2000, using mostly large ground-based optical telescopes, have discovered many more, all of which are irregular.
Young Ji International School / College
Page 75
Moons by primary
Selected moons, with the Earth to scale. Nineteen moons are large enough to be round, and one, Titan, has a substantial atmosphere.
The number of moons discovered in each year Mercury, the innermost planet, has no moons, or at least none that can be detected to a diameter of 1.6 km (1.0 mi). For a very short time in 1974, Mercury was thought to have a moon. Venus has no moons, though reports of a moon around Venus have circulated since the 17th century. Earth has one Moon, the largest moon of any rocky planet in the Solar System. Earth also has at least two co-orbitals: the asteroids3753 Cruithne and 2002 AA29; however, since they do not orbit Earth, they are not considered moons. (See Other moons of Earth and Quasi-satellite.) Mars has two known satellites, Phobos and Deimos ("fear" and "dread", after attendants of Ares, the Greek god of war, equivalent to the Roman Mars). Searches for more satellites have been unsuccessful, putting the maximum radius of any other satellites at 90 m (100 yd). Jupiter has 67 known moons with confirmed orbits. Its eight regular moons are grouped into the planet-sized Galilean moons and the far smaller Amalthea group. They are named after lovers of Zeus, the Greek equivalent of Jupiter. Its 59 known irregular moons are organized into two categories: prograde and retrograde. Young Ji International School / College
Page 76
The prograde satellites consist of the Himalia group and two others in groups of one. The retrograde moons are grouped into the Carme,Ananke and Pasiphae groups, as well as some isolated moons. Saturn has 62 moons with confirmed orbits, 53 of which have names, most of which are quite small. Seven moons are large enough to be in hydrostatic equilibrium, including Titan, the second largest moon in the Solar System. Twentyfour of Saturn's moons are regular, and traditionally named after Titans or other figures associated with the mythological Saturn. The remaining thirty-eight, all small, are irregular, and classified by their orbital characteristics into Inuit, Norse, and Gallic groups, and their names are chosen from the corresponding mythologies. The rings of Saturn are made up of icy objects ranging in size from one centimetre to hundreds of metres, each of which is on its own orbit about the planet. Thus a precise number of Saturnian moons cannot be given, as there is no objective boundary between the countless small anonymous objects that form Saturn's ring system and the larger objects that have been named as moons. At least 150 "moonlets" embedded in the rings have been detected by the disturbance they create in the surrounding ring material, though this is thought to be only a small sample of the total population of such objects. Uranus has 27 named moons, five of which are massive enough to have achieved hydrostatic equilibrium. There are another 13 inner moons that orbit within Uranus's ring system, and another nine outer irregular moons. Unlike most planetary moons, which are named from antiquity, all the moons of Uranus are named after characters from the works of Shakespeare and Alexander Pope's work The Rape of the Lock. Neptune has 14 named moons; the largest, Triton, accounts for more than 99.5 percent of all the mass orbiting the planet. Triton is large enough to have achieved hydrostatic equilibrium, but, uniquely for a large moon, has a retrograde orbit, suggesting it was captured. Neptune also has six known inner regular satellites, and six outer irregular satellites. Pluto has five moons. Its largest moon Charon, named after the ferryman who took souls across the River Styx, is more than half as large as Pluto itself, and large enough to orbit a point outside Pluto's surface. In effect, each orbits the other, forming a binary system informally referred to as a double-dwarf-planet. Pluto's four other moons, Nix, Hydra, Kerberos and Styx are far smaller and orbit the Pluto– Charon system. Among the dwarf planets, Ceres has no known moons. It is 90 percent certain that Ceres has no moons larger than 1 km in size, assuming that they would have the same albedo as Ceres itself.
Young Ji International School / College
Page 77
Terrestrial planet
The terrestrial planets Mercury, Venus, Earth and Mars in true colors, sizes to scale A terrestrial planet, telluric planet or rocky planet is aplanet that is composed primarily of silicate rocks ormetals. Within the Solar System, the terrestrial planets are the inner planets closest to the Sun. The terms "terrestrial planet" and "telluric planet" are derived from Latin words for Earth (Terra and Tellus), as these planets are, in terms of composition, "Earth-like". Terrestrial planets have a solid planetary surface, making them substantially different from the usually larger gas giants, which are composed mostly of some combination of hydrogen, helium, and water existing in various physical states. Structure All terrestrial planets have approximately the same type of structure: a central metallic core, mostly iron, with a surrounding silicate mantle. The Moon is similar, but has a much smaller iron core. Io and Europa are also satellites that have internal structures similar to that of terrestrial planets. Terrestrial planets can have canyons, craters, mountains, volcanoes, and other surface structures, depending on the presence of water and tectonic activity. Terrestrial planets possess secondary atmospheres, generated through internal volcanism or comet impacts, in contrast to the gas giants, whose atmospheres are primary, captured directly from the original solar nebula. Solar terrestrial planets
Relative masses of the terrestrial planets of the Solar System, including the Moon
Young Ji International School / College
Page 78
Earth's Solar System has four terrestrial planets: Mercury, Venus, Earth, and Mars. Only one terrestrial planet, Earth, is known to have an active hydrosphere. During the formation of the Solar System, there were probably many more "terrestrial" planetesimals, but most merged with or were ejected by the four terrestrial planets. Dwarf planets, like Ceres and Pluto, and other large asteroids are similar to terrestrial planets in the fact that they do have a solid surface, but are, on average, composed of more icy materials (Ceres and Pluto have a density of 2.1 g cm−3, and Haumea's density is similar to Pallas's 2.8 g cm−3). Density trends The uncompressed density of a terrestrial planet is the average density its materials would have at zero pressure. A greater uncompressed density indicates greater metal content. Uncompressed density differs from the true average density because compression within planet cores increases their density; the average density depends on planet size as well as composition. Densities of the terrestrial planets Object
Density (g cm−3) Mean Uncompressed
Semi-major axis (AU)
Mercury 5.4
5.3
0.39
Venus
5.2
4.4
0.72
Earth
5.5
4.4
1.0
Mars
3.9
3.8
1.5
The density of terrestrial planets trends towards lower values as the distance from the Sun increases. The rocky minor planet Vesta orbiting outside of Mars is less dense than Mars still, at 3.4 g cm−3. It is unknown whether extra solar terrestrial planets in general will also follow this trend. Concept Review 1. What does a comet‘s tail form as it approaches the sun? 2. How do a meteoroid. A meteor, and a meteorite differ/ 3. What type of feature might be formed on Earth if a large meteorite reached its surface? 4. Apply- describe differences among comets, meteorites, and asteroids? Understanding Concepts Complete each sentence. 1. The object around which all planets and stars were once believed to have orbited is ________. Young Ji International School / College
Page 79
2. 3. 4. 5.
Although it is the ninth planet from the sun, Pluto is like a(n) ______ planet. A greenhouse effect occurs on _____ and ______. Robots initiate the motion made by ______. In 2001, ______ will be the farthest planet from the sun. Think and Write Critically
1. 2. 3. 4. 5.
Contrast Copernicus‘ model of the solar system with Kepler‘s model. Describe the general characteristics of the inner and outer planets. Describe how the structure of a comet changes as it nears the sun. How is Uranus different from the other eight planets? Compare and contrasts mercury and Pluto. Apply
1. Why is the surface temperature on Venus so much higher than that on earths? 2. Describe the relationship between the mass of a planet and the number of satellites it has. 3. Why are probe landings on Jupiter or Saturn unlikely events? 4. What evidence suggests that water is once was present on Mars? 5. An observer on earth can watch Venus go through phases much like earth‘s moon does. Explain why this is so.
Chapter 8:
Planetary ring
The moons Prometheus and Pandora shepherd the F ring of Saturn. A planetary ring is a disk or ring of dust, moonlets, or other small objects orbiting a planet or similar body. The most notable planetary rings in the Solar System are those around Saturn, but the other three gas Young Ji International School / College
Page 80
giants (Jupiter, Uranus and Neptune) also possess ring systems. On 26 March 2014 was announced the discovery of rings around the minor planet Chariklo during the observation of a stellar occultationon 3 June 2013. Reports in March 2008 have suggested that the Saturnian moon Rhea may have its own tenuous ring system, which would make it the only moon known to possess a ring system. A later study published in 2010 revealed that imaging of Rhea from the Cassini mission was inconsistent with the predicted properties of the rings, suggesting that some other mechanism is responsible for the magnetic effects that had led to the ring hypothesis. Pluto is not known to have any ring systems, though the New Horizons probe might find a ring system when it visits in 2015.
The ring swirling around Saturnconsists of chunks of ice and dust. The little dark spot on Saturn is the shadow from Saturn's moon Enceladus. There are three ways that thicker planetary rings (the rings around planets) have been proposed to have formed: from material of the protoplanetary disk that was within the Roche limit of the planet and thus could not coalesce to form moons; from the debris of a moon that was disrupted by a large impact; or from the debris of a moon that was disrupted by tidal stresses when it passed within the planet's Roche limit. Most rings were thought to be unstable and to dissipate over the course of tens or hundreds of millions of years, but it now appears that Saturn's rings might be quite old, dating to the early days of the Solar System. Fainter planetary rings can form as a result of meteoroid impacts with moons orbiting around the planet or, in case of Saturn's E-ring, the ejecta of cryovolcanic material. The composition of ring particles varies; they may be silicate or icy dust. Larger rocks and boulders may also be present, and in 2007 tidal effects from eight 'moonlets' only a few hundred meters across were detected within Saturn's rings. Sometimes rings will have "shepherd" moons, small moons that orbit near the outer edges of rings or within gaps in the rings. The gravity of shepherd moons serves to maintain a sharply defined edge to the ring; material that drifts closer to the shepherd moon's orbit is either deflected back into the body of the ring, ejected from the system, or accreted onto the moon itself. Several of Jupiter's small innermost moons, namely Metis and Adrastea, are within Jupiter's ring system and are also within Jupiter's Roche limit. It is possible that these rings are composed of material that is being pulled off these two bodies by Jupiter's tidal forces, possibly facilitated by impacts of ring material on their surfaces.
Young Ji International School / College
Page 81
Uranus's Îľ ring also has two shepherd satellites, Cordelia and Ophelia, acting as inner and outer shepherds respectively. Both moons are well within Uranus' synchronous orbit radius, and their orbits are therefore slowly decaying due to tidal deceleration.[14] Neptune's rings are very unusual in that they first appeared to be composed of incomplete arcs in Earth-based observations, but Voyager 2's images showed them to be complete rings with bright clumps. It is thought that the gravitational influence of the shepherd moon Galatea and possibly other as-yet undiscovered shepherd moons are responsible for this clumsiness. Pluto is not known to have any ring systems. However, some astronomers think that the New Horizons probe might find a ring system when it visits in 2015. It is also predicted that Phobos, a moon of Mars, will break up and form into a planetary ring in about 50 million years due to its low orbit. Pluto loses Planet X title
Discovery image of Charon To the observatory's disappointment and surprise, Pluto showed no visible disc; it appeared as a point, no different from a star, and, at only 15th magnitude, was six times dimmer than Lowell had predicted, which meant it was either very small, or very dark. Since Lowell astronomers thought Pluto was massive enough to perturb planets, they assumed that it should have an albedo of 0.07 (meaning that it reflected only 7% of the light that hit it); about as dark as asphalt and similar to that of Mercury, the least reflective planet known. This would give Pluto an assumed diameter of about 8,000 km, or about 60% that of Earth. Observations also revealed that Pluto's orbit was very elliptical, far more than for any other planet. Some astronomers disputed Pluto's status as a planet. Shortly after its discovery in 1930, Armin O. Leuschner suggested that its dimness and high orbital eccentricity made it more similar to an asteroid or comet; "The Lowell result confirms the possible high eccentricity announced by us on April 5. Among the possibilities is a large asteroid greatly disturbed in its orbit by close approach to a major planet such as Jupiter, or it may be one of many long-period planetary objects yet to be discovered, or a bright cometary object." In 1931, Ernest W. Brown asserted, using a mathematical formula that the observed irregularities in the orbit of Uranus could not be due to the gravitational effect of a more distant planet, and thus that Lowell's supposed prediction was "purely accidental". Young Ji International School / College
Page 82
Throughout the mid-20th century, estimates of Pluto's mass were revised downward. In 1931, Nicholson and Mayall calculated its mass, based on its supposed effect on the gas giants, as roughly that of the Earth, while in 1949, measurements of Pluto's diameter led to the conclusion that it was midway in size between Mercury and Mars and that its mass was most probably about 0.1 Earth mass. In 1976, Dale Cruikshank, Carl Pilcher and David Morrison of the University of Hawaii analyzed spectra from Pluto's surface and determined that it must contain methane ice, which is highly reflective. This meant that Pluto, far from being dark, was in fact exceptionally bright, and thus was probably no more than 0.01 Earth mass. Size estimates for Pluto: Year Mass
Notes
1931 1 Earth
Nicholson & Mayall
1948 .1 (1/10 Earth)
Kuiper
1976 .01 (1/100 Earth) Cruikshank, Pilcher, & Morrison 1978 .002 (1/500 Earth) Christy & Harrington Pluto's size was finally determined conclusively in 1978, when American astronomer James W. Christy discovered its moon Charon. This enabled him, together with Robert Sutton Harrington of the US Naval Observatory, to measure the mass of the Pluto–Charon system directly by observing the moon's orbital motion around Pluto. They determined Pluto's mass to be 1.31×1022 kg; roughly one fivehundredth that of the Earth or one sixth that of the Moon, and far too small to account for the observed discrepancies in the orbits of the outer planets. Lowell's "prediction" had been a coincidence: if there was a Planet X, it was not Pluto. Comet A comet is a relatively small solar system body that orbits the Sun. When close enough to the Sun they display a visible coma (a fuzzy outline or atmosphere due to solar radiation) and sometimes a tail. Asteroid Asteroids are small solar system bodies that orbit the Sun. Made of rock and metal, they can also contain organic compounds. Asteroids are similar to comets but do not have a visible coma (fuzzy outline and tail) like comets do. Meteoroid A meteoroid is a small rock or particle of debris in our solar system. They range in size from dust to around 10 meters in diameter (larger objects are usually referred to as asteroids). Meteor A meteoroid that burns up as it passes through the Earth‘s atmosphere is known as a meteor. If you‘ve ever looked up at the sky at night and seen a streak of light or ‗shooting star‘ what you are actually seeing is a meteor. Young Ji International School / College
Page 83
Meteorite A meteoroid that survives falling through the Earth‘s atmosphere and colliding with the Earth‘s surface is known as a meteorite. Asteroids are minor planets, especially those of the inner Solar System. The larger ones have also been called planetoids. These terms have historically been applied to any astronomical object orbiting the Sun that did not show the disk of a planet and was not observed to have the characteristics of an active comet, but as minor planets in the outer Solar System were discovered, their volatile-based surfaces were found to resemble comets more closely and so were often distinguished from traditional asteroids. Thus the term asteroid has come increasingly to refer specifically to the small bodies of the inner Solar System out to the orbit of Jupiter. They are grouped with the outer bodies—centaurs, Neptune trojans, and trans-Neptunian objects—as minor planets, which is the term preferred in astronomical circles. In this article the term "asteroid" refers to the minor planets of the inner Solar System. There are millions of asteroids, many thought to be the shattered remnants of planetesimals, bodies within the young Sun's solar nebula that never grew large enough to become planets. The large majority of known asteroids orbit in the asteroid belt between the orbits of Mars and Jupiter, or are co-orbital with Jupiter (the Jupiter Trojans). However, other orbital families exist with significant populations, including the near-Earth asteroids. Individual asteroids are classified by their characteristic spectra, with the majority falling into three main groups: Ctype, S-type, and M-type. These were named after and are generally identified with carbon-rich, stony, and metallic compositions, respectively. A comet is an icy small Solar System body that, when passing close to the Sun, heats up and begins to outgas, displaying a visible atmosphere or coma, and sometimes also a tail. These phenomena are due to the effects of solar radiation and the solar wind upon the nucleus of the comet. Comet nuclei range from a few hundred meters to tens of kilometres across and are composed of loose collections of ice, dust, and small rocky particles. The coma and tail are much larger and, if sufficiently bright, may be seen from the Earth without the aid of a telescope. Comets have been observed and recorded since ancient times by many different cultures. Comets have a wide range of orbital periods, ranging from several years to several millions of years. Short-period comets originate in the Kuiper belt or its associated scattered disc, which lie beyond the orbit of Neptune. Longer-period comets are thought to originate in the Oort cloud, a spherical cloud of icy bodies extending from outside the Kuiper Belt to halfway to the next nearest star. Longperiod comets are directed towards the Sun from the Oort cloud by gravitational perturbations caused by passing stars and the galactic tide. Hyperbolic comets may pass once through the inner Solar System before being flung out to interstellar space along hyperbolic trajectories. Comets are distinguished from asteroids by the presence of an extended, gravitationally unbound atmosphere surrounding their central nucleus. This atmosphere has parts termed the coma (the central atmosphere immediately Young Ji International School / College
Page 84
surrounding the nucleus) and the tail (a typically linear section consisting of dust or gas blown out from the coma by the Sun's light pressure or out streaming solar wind plasma). However, extinct comets that have passed close to the Sun many times have lost nearly all of their volatile ices and dust and may come to resemble small asteroids. Asteroids are thought to have a different origin from comets, having formed inside the orbit of Jupiter rather than in the outer Solar System. The discovery of main-belt comets and active centaurs has blurred the distinction between asteroids and comets. A meteoroid is a small rocky or metallic body travelling through space. Meteoroids are significantly smaller than asteroids, and range in size from small grains to 1 meter-wide objects. Smaller objects than this are classified as micrometeoroids or space dust. Most are fragments from comets or asteroids, while others are collision impact debris ejected from bodies such as the Moon or Mars. When such an object enters the Earth's atmosphere at a speed typically in excess of 20 km/s, aerodynamic heating produces a streak of light, both from the glowing object and the trail of glowing particles that it leaves in its wake. This phenomenon is called a meteor, or colloquially a "shooting star" or "falling star". A series of many meteors appearing seconds or minutes apart, and appearing to originate from the same fixed point in the sky, is called a meteor shower. Incoming objects larger than several meters (asteroids or comets) can explode in the air. If a meteoroid, comet or asteroid or a piece thereof withstands ablation from its atmospheric entry and impacts with the ground, then it is called a meteorite. Key Terms 1. Escape velocity 2. Solar wind 3. Terrestrial planets 4. Jovian planets 5. Mercury 6. Venus 7. Mars 8. Spirit 9. Opportunity 10. Blob tectonics 11. Maria 12. Jupiter 13. Europa 14. Titan 15. Pluto 16. Triton 17. Tail 18. Comet Young Ji International School / College
Page 85
19. Meteor 20. Coma Concept Review 1. Explain how Earth‘s revolution affects constellations that are visible throughout the year. 2. Explain how Venusians tectonics differs from tectonics on earth. 3. Why are there fewer meteorite craters visible on Venus than on Mercury? 4. Discuss the evidence that the Martian atmosphere was once considerably different than it is today.
Young Ji International School / College
Page 86