The Science Behind Air Pressure
Air is made of tiny gas particles that are always moving. Air pressure is the force of air pushing down on everything.
- When air is heated, it expands and takes up more space.
- When air cools, it contracts and takes up less space, creating lower pressure inside a container.
Weight of Air on us:
Our bodies are filled with air, too, and the pressure inside us balances out the pressure outside! The fluids in our body push outward with the same force that the air outside is pushing inward.
Lifting Heavy Objects:
Airplanes fly because fast-moving air over the wings creates low pressure, and higher pressure below lifts the plane.
How Air Pressure Can Crush a Can
Can-Crushing Experiment:
- Fill an empty soda can with a little water.
- Heat the can over a flame until the water boils and becomes steam.
- Quickly flip the can upside down into ice-cold water.
- The can collapses instantly!
Why This Happens:
- Heating the can turns water into steam, pushing most of the air out.
- When placed in cold water, the steam quickly condenses back into water, leaving an empty space (low pressure) inside the can.
- The higher air pressure outside the can crushes it!
Fun Facts
Here are some interesting facts about air pressure:
- A standard airplane cabin has lower pressure than sea level, so your ears pop!
- The strongest recorded wind gust was over 250 mph – powered by air pressure!
- A vacuum is a space with no air pressure, like outer space.
- Extreme differences in air pressure cause tornadoes and hurricanes.
Review
Let’s quickly recap what we learned about air pressure:
- What is the force of air pushing on everything called? Air pressure
- What happens to air when it is heated? Expands
- What happens to air when it is cooled? Contracts
- What gas fills the can when the water boils? Steam
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