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SIMPLE SCIENCE EXPERIMENTS by Tomislav Sen}anski
Illustrator
Nemanja Ristić
Introduction What you have before you is the fourth book with interesting and diverse experiments. Some of them are simple, some are complex, but they can all be done with things you can find at home. Experiments in this book deal with a number of scientific concepts, and models, analogies and animations are used to help conduct them. Models are there to demonstrate the dynamics of a process. Analogies are similar but simplified procedures that explain certain physical phenomena. Animations are there to recommend the use of additional materials, and they make experiments come alive. Experiments are extremely important exercises that boost self-esteem and help display initiative freely, and they produce the desire to study and work. By doing experiments, readers comprehend the world around them better—the world ruled by physical laws. The Author
Table of Contents Characteristics of Physical Bodies What Fits in a Glass .......................................................................... 7 Funnel and Flame ............................................................................ 8 Folding a Piece of Paper ................................................................ 9 Black and White ............................................................................. 10 Cold and Warm Foot .................................................................... 11 Who Runs Away from Whom .................................................... 12 Acrobat Coin ................................................................................... 13 On the Edge of a Table ................................................................ 14 Needles in the Role of Magnets .............................................. 15 Air in its Space ................................................................................ 16 How to Drink Through a Straw ................................................ 17 Motion Motion of Bubbles ........................................................................ Motion of Balls ............................................................................... Pen Trajectory ................................................................................ Domino Effect ................................................................................ Travelling Blow .............................................................................. Dance of Pearls .............................................................................. Trace Left by a Swing ................................................................... Rebound of a Tennis Ball ............................................................
18 19 20 21 22 23 24 25
Force Water as Force ................................................................................ 26 Model of Combined Forces ........................................................ 27 Centrifugal Force (Sprayer)......................................................... 28 Centripetal Force (Swinging a Glass of Water Over Your Head) ............................................................................. 29 Box Wheels ....................................................................................... 30 On a Roller Coaster ........................................................................ 31 Pressure Breathing Balloon .......................................................................... 32 Invisible Crane ................................................................................ 33 Ball between Water and Air ........................................................ 34 When Ships Collide ....................................................................... 35 Wind Indicator ................................................................................ 36 Measuring the Speed of Wind .................................................. 37 Sand as Indicator of Pressure .................................................... 38 Egg Experiment .............................................................................. 39
Energy Just Like in Amusement Park .................................................... 40 Clothespin Catapult ...................................................................... 41 Naughty Button .............................................................................. 42 Spinning Top.................................................................................... 43 Crumpled Paper ............................................................................. 44 Spinning Decoration..................................................................... 45 Sound Where Sound Comes From ........................................................ 46 Orchestra .......................................................................................... 47 Paper Trumpet ................................................................................ 48 Whistling with a Blade of Grass ................................................ 49 Hearing Through a Stethoscope .............................................. 50 Singing Fork ..................................................................................... 51 Sound of a Ruler ............................................................................. 52 Sea Waves in a Room .................................................................... 53 Electricity Fluttering Leaves ........................................................................... 54 Sensitive Electroscope ................................................................. 55 Conductors from Home .............................................................. 56 Paper Fringe .................................................................................... 57 How to Move Cardinal Directions ............................................ 58 Electricity as Cleaning Force ...................................................... 59 Light Indecisive Arrow ............................................................................ 60 How Eyes See................................................................................... 61 Sharp Eye .......................................................................................... 62 Cutting Rope Without Touching .............................................. 63 Feather as Prism ............................................................................. 64 Why We Have Two Eyes ............................................................... 65 Blind Spot ......................................................................................... 66 Why Eye Pupil Changes ............................................................... 67 Disappearing Coin ......................................................................... 68 Colored Windmill ........................................................................... 69 Disappearing Colors ..................................................................... 70 Chameleon Flower ....................................................................... 71
C h a r a ct e r i s t i c s o f P h y s i c a l B o d i e s There are many physical bodies around us. They differ in shape, solidity, temperature, composition and many other characteristics that we can find out more about with our senses. Becoming acquainted with them is very important for everyday life.
What Fits in a Glass There is still room for sugar in a cup full of tea. There is room for milk in a cup filled with crushed biscuits. Nothing will spill out! Do an experiment with two different substances and see if what we are saying here is true.
ir ed : M at er ia ls re q u да
две чаше, вата, во
1. Fill a glass with cotton wool to the top. Fill another glass with water. 2. Slowly pour the water into the glass filled with cotton wool and see if the water will spill out.
What is going to happen? Water will fit the glass without spilling out.
Reason: There are empty spaces between particles (molecules) that every physical body is made of. The molecules of water fill the empty spaces between the molecules of cotton wool, and the other way around, which is why none of the glass contents spills out. 7
Characteristics of Physical Bodies
Funnel and Flame ir ed : M at er ia ls re q u
When exposed to wind, the flame of candle becomes restless and bends in all directions. Do an experiment and see what it is that makes a flame bend.
el
a lit candle, a funn
1. Put the candle on a table, then
What is going to happen? gently blow through the funnel towards it, in a way that won’t extinguish the candle, but make the flame bend. 2. Turn the funnel to the other side and blow through it again towards the candle. See what is going to happen to the flame.
When the air goes through the narrow part of the funnel, the flame bends away from the funnel. When the air comes out of the wide part of the funnel, the flame bends towards the funnel.
The reason why: When the air comes out of the narrow part of the funnel, the air currents separate and go different ways, making the flame move in the same direction as the air currents. When the air comes out of the wider part of the funnel, the air currents separate while still inside the funnel. The currents hit the walls of the funnel, change the direction and whirl, which is why the air reaches the flame from behind the candle and bends it towards the inside of the wider part of the funnel.
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Characteristics of Physical Bodies
Folding a Piece of Paper ir ed : M at er ia ls re q u
A piece of paper is easily folded. Try and see how many times you can fold it. Then try the same thing with pieces of paper of different sizes.
pieces of paper of
different sizes
1.  Fold every piece of paper as many times as you can. 2.  Make a note of the number of times you managed to fold each piece. What is going to happen? You won’t be able to fold any of the pieces of paper more than seven times.
The reason why: Pieces of paper become multilayered by folding. When a piece of paper is folded several times, the number of layers is so big that it cannot be folded any more. Even very thin paper is very difficult to fold after the number of layers reaches more than one hundred, which happens after paper is folded seven times. 9
Characteristics of Physical Bodies
Black and White When, on a sunny day, you touch an object that has been exposed to the sun, you with feel warmth. However, this can also be very unpleasant, especially if the object is dark. Do an experiment and see what it is about.
ir ed : M at er ia ls re q u
s, a piece of two thermometer per. black and white pa
Note: This experiment should be carried out in the sun. You can use 1. Стави термометар на бели папир и после only one thermometer, in which case минут-два очитај с њега температуру. the readings should be done one 2. Стави термометар на црни папир и после after the other. Between the readings, минут-два поново очитај температуру. the scale of the thermometer should be reduced to its starting value.
What is going to happen?
The temperature indicated by the thermometer placed on the piece of white paper will be lower than the one indicated by the thermometer placed on the piece of black paper.
The reason why: The black paper absorbs more sun rays, becomes warmer, and it emanates the warmth towards the thermometer placed on it, which then indicates a higher temperature.
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Characteristics of Physical Bodies
C o ld an d Wa rm Foot How would we feel if we walked around barefoot? In the summer, concrete becomes hot very quickly and it would burn our feet. In the winter, it is freezing cold and we would be very cold. Shoe soles protect feet from unpleasant temperatures. Do an experiment and see what it is about.
ir ed : M at er ia ls re q u
lder and a cardboard file fo r. plastic book cove
1.  Place the cardboard file folder and the plastic book
cover on a floor with ceramic tiles. 2.  Place one bare foot on the folder and the other on the plastic cover. Estimate the temperature of both materials.
What is going to happen? You will have a feeling that the plastic cover is colder than the cardboard folder.
The reason why: Before doing the experiment, the plastic cover and the cardboard folder have the same temperature since they are in the same room. When you stand on them, the warmth from your feet is transferred to them and onwards to the tiles. Plastic conducts heat more quickly than cardboard, which is why your foot placed on the plastic cover is cold. Cardboard conducts heat more slowly, and the warmth of your other foot is transferred more slowly to the tiles, which is why you have the impression that cardboard is warmer than plastic. 11
Shoemakers are familiar with characteristics of different materials, and they chose materials that are good insulators of heat.
Characteristics of Physical Bodies
s Away from Whom n u R o Wh
ir ed : M at er ia ls re q u
Many fabrics in the house need to be shook out from time to time: the tablecloth, the carpet, the sofa cover. Do an experiment and see what it is about.
a rug, a rug beater
1.  Place the rug over a metal bar. 2.  Beat it with the rug beater. What is going to happen? A cloud of dust is created around the rug. After some beating the rug is cleaner.
The reason why: The rug moves when you beat it, and the dust stays in the same place due to inertia, in other words it remains motionless and then falls to the ground because of the force of gravity. It means that the rug is forced out of the dust, and not the dust out of the rug.
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Characteristics of Physical Bodies
Acrobat Coin Inertia can make hygiene maintenance rather difficult. If you gather different forms of debris (chocolate papers, school eraser or rubber residue, etc.), put them on a plate and try carrying them quickly to the rubbish bin, they all may end up on the floor. Do an experiment that won’t make a mess to see what it is about.
ir ed : M at er ia ls re q u
of thin cardboard, a little jar, a piece a pen, a coin. some duct tape,
1. Cut the cardboard into a band, bend it into a
hoop and connect the ends with duct tape. 2. Place the hoop on top of the jar, and a coin on top of the hoop. 3. Put the pen on the inside of the hoop and pull the hoop forcefully to the side.
What is going to happen? The hoop will move, and the coin will fall into the jar.
The reason why: When you move the hoop with an abrupt movement away from the top of the jar, the coin remains in its place, and then it falls into the jar. Inertia, which allows physical bodies to remain motionless or to continue moving at an even pace, prevents the coin from moving for a moment, and then the coin falls into the jar due to the force of gravity. 13
Characteristics of Physical Bodies
On the Edge of a Tabl e If an object is placed on the edge of a table, it can easily happen that it ends up on the floor. Do an experiment and examine why it happens, and how to place the object in a way that the object doesn’t fall dawn.
ir ed : M at er ia ls re q u
box, a piece of a little cardboard heavy object, metal or a small, a table, a pen
1. Move the box along the edge of the table until you can place it so that it is stable. 2. Use the color blue to mark the box where the edge is. 3. Put the metal object in the part of the box which is above the table and find its
new point of balance. 4. Use the color red to mark the box where the edge is, and compare it to the blue marking.
What is going to happen? The marking put on the empty box is close to the middle of the box, while the marking on the box containing a metal object is closer to the end where the metal object is put.
The reason why: The box is stable when its centre of gravity goes through the area where the box covers the surface of the table. By placing a metal object in the box we move its centre of gravity.
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• Can you hear the sound of a ruler? • Can a flower change color like a chameleon? • How many times can you fold a piece of paper? • What happens when you swing a glass of water over your head? • How can you make a balloon inhale? • How can you make catapult out of a swing?
Simple Science Experiments contain a large number of ideas for scientific experiments that children can carry out without any danger, either alone or with a little help from adults. In the course of doing these experiments the children will have fun, and at the same time they will get to know some of the basic laws of science. Experiments also stimulate children’s imagination and show them that science is amazing and all around us.