With this experiment you can make a coin click and dance on the mouth of an empty bottle.
Things Required:
2-litre soda bottle
Small coin
Cup of water
Directions:
Place the empty, uncapped soda bottle in the freezer for five minutes. Remove the bottle from the freezer and immediately cover the mouth with the wet coin. Wet the coin by dipping the coin in the cup of water.
This Is What Happens:
Within seconds, the coin starts to make a clicking sound as it rises and falls.
Science Behind It:
Cooling causes matter to contract. The air in the bottle contracts and takes up less space. This allows more cold air to flow into the bottle. When removed from the freezer, this cold air starts to heat up and expand. The gas exerts enough pressure on the coin to cause it to rise on one side. The coin falls when the excess gas escapes. This process continues until the temperature inside the bottle equals that outside.
