When everyone else is out of her classroom, Amy takes over and does some quite amazing experiments. She specializes in discrepant events. Watch and try to predict what will happen. Expect to be quite amazed.

This month, Amy does "Can Crusher," an experiment that demonstrates how air exerts pressure.

Watch Amy perform the experiment. (2638k)
Watch the results of the experiment. (2476k)

Can Crusher

Materials
hot plate
gallon metal can with cap
water (approximately 6 ounces)
safety glasses and gloves

Procedure
1. Heat the hot plate.
2. Pour the water into the can.
3. Place the can on the hot plate and allow the can to heat.
4. Once the water boils, steam will be visible. Remove the can from the hot plate and quickly put the cap on the can. Tighten the cap.
5. Stand back and watch.

Background
Can Crusher demonstrates an important principle of air, that is, air exerts pressure. Most people are surprised to see the air exert enough pressure to crush a can. The thermal expansion of the heated gas molecules inside the can forces some of the air out of the can. After the can is capped and removed from the heat, the gas molecules begin to cool and contract. This leaves areas of very low air pressure. Meanwhile, the air outside of the can is at higher pressure. As soon as it can, the outside air rushes to exert its pressure on the lower pressure inside. As the two pressures collide, the can crumples.

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