- Aluminum Can
- Oven Mitt and Tongs
- Tap Water
- Hot Plate
- Dish or Pan or Cold Water
Procedure
Put a tablespoon of water in the aluminum can and place it on the hot plate. Heat the can and water until the water is boiling. This will likely take a few minutes. Steam will come out of the hole in the can when the water is boiling. Let the can steam for about a minute to maximize the ratio of water vapor to dry air inside the can. As rapidly and carefully as possible remove the can from the hot plate, turn it upside down, and submerge the top of the can in the water. The can should be crushed!
Explanation
When the can is first place on the hot plate it is filled with air, (except for the little water in the can), and there is no difference between the air pressure on the inside and outside of the can. When the water begins to boil the gaseous water vapor begins to take up some of the volume of the can and force out dry air. As the can top is put into the water, the can and the hot water vapor are cooled. The water vapor condenses back into liquid water, air is not able to push in and fill up that volume. With very little air inside the can the air pressure inside the can is much less than the air pressure outside of it. The can is crushed by the inward forces exerted by the pressure difference. Also, since the air pressure pushing down on the water outside the can is much greater than the air pressure pushing down on the water through the drinking hole, water is drawn up in the can.
