Air PressureAir Occupies Space

Air Exerts Pressure

Experiment #1Air Occupies Space

Fill a beaker/bowl three quarters full with water.

Place a piece of paper halfway down a test tube/glass.

Push the glass, mouth first, into the water and ……

Lift it out again.

Remove the paper.

Is it wet?

Why?

Paper is not wet because air in the glass is taking up the space.

Try pushing down on the handle of a bicycle pump while closing the nozzle of the pump with your thumb. Notice what happens …..

Discuss your experience with your classmates.

Experiment # 2

The Collapsing Can

Add a small amount of water in empty cans and let it boil until all of it evaporates.

Remove the cans from the Bunsen burner/stove and immerse the cans in a bowl of cold water or place them under cold flowing water from the tap. Notice what happens……

Both cans collapsed… wow…

What happened?

When the water boils in the cans, it changes into steam.

Steam drives all the air inside, out of the cans.

As the can immerses into the cold water water, the steam immediately condenses into water.

As the air is removed from inside the can, the weight of the air/atmospheric pressure crushes the container.

Experiment # 3

Hard Boiled Egg

Hard boiled egg doesn’t go through the narrow mouth of a conical flask/ bottle.

Light a candle inside the bottle and……

Put the hard boiled egg on its mouth. Immediately.

Egg goes inside the bottle

What happened?

When the candle burns, oxygen is used up.

This reduces the amount of air in the bottle, which decreases the air pressure inside the flask.

The higher pressure outside the flask then pushes the egg in.

Produced by

Khaula Shehzad

Audio by

Shorthopper