This video demonstrates the expansion of gases with the help of a bottle and a coin.
Here is what you need:, glass bottle, coin, water, pipette, 1. Put a few drops of water on one face of the coin, to act as a sealant., 2. Place the coin on the mouth of the glass bottle with the wet face down. Make sure it fits tight., 3. Wrap the bottle with both of your hands., 4. Wait a little bit., What do you think?, Why does the coin rise on the mouth of the bottle?, Explanation: , The warmth of our hands heats up the air inside the bottle and thereby increases its pressure., When the force resulting from the internal air pressure exceeds the weight of the coin, it pushes the coin up for a moment.