Air and aerodynamics
What is air? • Do jar experiment • We live at the bottom of an ocean of air. This mixture of gases are called the Atmosphere. • Make up of the air: 78% nitrogen 21% oxygen 2% other gases Water is also in the air but %varies from day to day.
What is Air Pressure? • The weight of our air presses down on us. This is called atmospheric pressure or AIR PRESSURE. • You are not crushed because it presses from all sides the same • The higher up the lower the air pressure • *Book Experiment*/Plunger • There is more air pressure at the sea level the the top of mountains
Proof air exist 1 • Air does exist however it is invisible. • Experiment- Flame under a jar in water
• Fire needs Oxygen to burn. Oxygen is invisible and part of air. Therefore the flame goes out because it runs out of air. • The flame goes out because it uses up something in the air
Proof Air exist 2 • If Air exist then it will occupy space • Experiment with paper in the jar
QuickTime™ and a TIFF (LZW) decompressor are needed to see this picture.
• The paper will not get wet because there is a layer of air separating the water and the paper
Proof Air exist 3 • If air exist and if it is made of molecules then it must have weight • Poster paper experiment • The paper has air pressing down on it making it heaver then it appears. As a result the ruler does not work to lift it well.
Can air pressure be contained? • If we need a specific air pressure (higher or lower) we can seal off in in an air tight container. • Upside down jar experiment
• The air on the top of the jar is lower then the air pressure outside as there is less air trapped inside.The higher air pressure outside actually helps by pressing on on the paper to help keep the seal in place • That keeps the paper in place. It later drops due to the fact that air from the outside is leaking in
Uses of Air • Air is made of molecules. Unlike solids and liquids, the molecules are far apart. • Because of the fact there is so much space the molecules can be pressed together or compressed. This is called COMPRESSED AIR. • It exerts a lot of pressure andcan be used in balls, balloons, tires and tools
Properties of Air pressure Air pressure will try to equalize when it meets an area of lower or higher air pressure Here, the higher air pressure in the ball will fill the lower air pressure in the bag QuickTime™ and a TIFF (LZW) decompressor are needed to see this picture.
What is Aerodynamics? •
Gas molecules (particles) are in constant motion and because of it it acts a certain way. The unique way air acts is called AERODYNAMICS. Air acts as both a liquid and a gas 1. Liquid as it can flow around surfaces 2. Gases as it can be compressed. When air resists being compressed we call that air resistance. (in other words it presses back
How air acts like a liquid • Air can move around obsticles like water can.
• Flame experiment with a can in the way • The flame will flicker and may go out because the air molecules cling to the side of the can and move around it before meeting the air from the other side and moving on.
Famous Scientist Daniel Bernoulli • Bernoulli noticed that moving air acted like moving water. He also noticed that as the speed of air increased the amount of pressure it it has lowers. We call that Bernoulli’s Principle
What is Lift?
• As air moves that can effect air pressure. • Bent sheet experiment • The sheet will cave in. This is because the air QuickTime™ and a TIFF (LZW) decompressor are needed to see this picture. moving inside lowers the air pressure inside and the high pressure outside pushes in • Lifting paper experiment The air moving above lowers the air pressure above. QuickTime™ and a The air pressure below pushesareTIFF (LZW) decompressor needed to see this picture. the paper up. Lift is the force that pushes up an object.
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Insect flight