What you need:
An empty aluminium soft drink can
A big bowl and a pair of kitchen tongs
What to do:
1. Fill the bowl with cold water.
2. Put two tablespoons of water into the empty can.
3. Ask an adult to heat the can over a stove to boil the water. Use the tongs to hold the can. When the water boils watch the can. A cloud of steam will escape from the opening. Let the water boil for about 30 seconds.
4. Quickly turn the can upside down and dip it into the water in the bowl, making sure that it is fully immersed. Pour some cold water over it to cool it fast.
5. Does the water in the bowl flow into the hole in the can? Or does something else happen?
What happens?
Bang! The can will collapse almost immediately. Some water from the pan may get into the can, but not fast enough to fill the can before the air outside crushes it.
Why?
When you heat the can you make the water boil.
The vapour from the boiling water pushes the cool air out of the can.
When the can is filled with water vapour, it is cooled suddenly when turned upside down in the water.
Cooling the can condenses the water vapour inside the can.
This leaves less air in the can than there was originally. When this happens, the pressure of air outside the can is greater than the pressure inside. This causes the air outside to crush the can.
Picture Credit : Google
