What Do These Things Have What Do These Things Have In Common?In Common?

These objects need These objects need air pressure to air pressure to

work!work!

What is Air Pressure?What is Air Pressure?

What is your guess? What is your guess?

Air Pressure…Air Pressure… pushes on everything it touches!pushes on everything it touches! is all around you!is all around you!

BUT……BUT…… I don’t see it! I don’t see it! I don’t feel it!I don’t feel it!

Air Pressure Pushes Down Air Pressure Pushes Down on on

Pig Pen!Pig Pen!

We Can Watch Air Pressure We Can Watch Air Pressure Work!Work!

Watch This!!Watch This!!

What Just Happened?What Just Happened?

What pushed the egg into the jar?What pushed the egg into the jar?

How strong is air pressure?How strong is air pressure?

Why don’t we get squashed Why don’t we get squashed

by air pressure? by air pressure?

Here is what Here is what happened…happened…

1. 1. The matches warm the air in The matches warm the air in

the bottle. When air is heated, the bottle. When air is heated,

it takes up more space, and it pushesit takes up more space, and it pushes

against the sides of the bottle. against the sides of the bottle.

2. Some of the warm air tries to escape2. Some of the warm air tries to escape

out of the bottle.out of the bottle.

3. And when the matches go out, the air in the3. And when the matches go out, the air in the

bottle becomes cooler. bottle becomes cooler.

4. The cooler air takes up less space.4. The cooler air takes up less space.

5. Now, the air outside the bottle pushes with5. Now, the air outside the bottle pushes with

greater power than the air inside the bottle.greater power than the air inside the bottle.

6. The greater pressure outside 6. The greater pressure outside

pushes the egg into the bottle!pushes the egg into the bottle!

Air Pressure Doesn’t Air Pressure Doesn’t Squash You Because…Squash You Because…

You have air inside of you. It You have air inside of you. It pushes out with the same pushes out with the same

amount of pressure that the amount of pressure that the outside air pushes in on you.outside air pushes in on you.

Another reason air Another reason air pressure doesn’t squash pressure doesn’t squash

you is because…you is because… Air pushes in all directions!! Air pushes in all directions!!

Let’s try an experiment!Let’s try an experiment!

Sometimes You Can Feel Sometimes You Can Feel Air Pressure Change!Air Pressure Change!

Have your ears ever popped when Have your ears ever popped when you’ve gone up a mountain or up you’ve gone up a mountain or up

in an airplane?in an airplane?

Do you know why?Do you know why?

Air Pressure ChangesAir Pressure ChangesThe higher you go, the less air pressureThe higher you go, the less air pressurepushes.pushes.

Your ears popYour ears popbecause they because they are trying to are trying to make the insidemake the insideand outsideand outsidepressure equal.pressure equal.

Up here I have little weight on me. I feel little

pressure.

Down here I have lots of weight on me. I feel high

pressure.

So…as you go up, the airSo…as you go up, the airin your ears pushes out.in your ears pushes out.

Oww,

my

ears!

!

Calvin & Hobbes are climbing to the top Calvin & Hobbes are climbing to the top of a mountain. Will the air push against of a mountain. Will the air push against them more or less when they reach the them more or less when they reach the

top? Explain your answer.top? Explain your answer.

Answer: LessAnswer: LessThe higher they go, the less air The higher they go, the less air

there is to push on them. there is to push on them.

1.1. With your partner, make up a song With your partner, make up a song about air pressure.about air pressure.

2.2. Write down the words on a piece of Write down the words on a piece of paper.paper.

3.3. Sing your song for another group.Sing your song for another group.

4.4. If you want, you can sing it for the If you want, you can sing it for the class.class.

This is what you do…

……to be continuedto be continuedFind out how air pressure can Find out how air pressure can make the weather be sunny or make the weather be sunny or

rainy!rainy!

What’s your guess??!!