# How to show the effects of water pressure & air pressure for kids

Written by tracy morris
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Both air and water exert pressure on living creatures constantly, but this pressure is not always obvious. If you are trying to teach children about the effect of water and air pressure, simply telling them about the presence of the pressure may not be enough. An experiment can make an impression on a child when words aren't enough. Perform a few simple experiments to show children the effects of water and air pressure.

Skill level:
Easy

### Things you need

• Rubber balloon
• Cake pan
• Kitchen tongs
• Empty soda can
• Tin can
• Nail
• Hammer
• Ruler

## Instructions

1. 1

Blow up a balloon and hold the mouth closed. Hold the balloon up and explain that the air inside the balloon is forced into a tiny space. Because of this, the air inside is under high pressure. The high pressure of the air inside the balloon is what stretches the balloon into a larger shape.

2. 2

Let the balloon go. Explain that once the neck of the balloon is no longer held closed, the air rushes from the high pressure area to a lower pressure area. As a result, the balloon deflates and returns to its original shape.

3. 3

Fill a cake pan 3 inches full of cold water.

4. 4

Place 1 tbsp of water into an empty cola can.

5. 5

Hold the can upright with a pair of tongs and heat the can over a stove until the water in the can boils. The vapour pressure inside the can will force the air out of the can.

6. 6

Turn the can over and place the mouth of the can under the cool water. The can will crush once the mouth is submerged. Explain that the can crushes because the pressure inside the can is lower than it is outside the can.

1. 1

Place a nail up against a tin can.

2. 2

Hammer the nail through the can to punch a hole in the can. Remove the nail and set the hammer and nail aside.

3. 3

Place the can on the lip of a sink so that the can is level and the hole points in the direction of the sink.

4. 4

Fill the can halfway full of water. Measure the distance of the arc made by the water coming out of the nail hole.

5. 5

Fill the can fully. Measure the distance of the arc made by the water coming out of the nail hole. The arc of water will be longer for the full can than for the can only filled halfway. As the level of water in the can lowers, the water pressure also lowers and the arch becomes shorter. Explain this to the kids watching the experiment.

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