Are you looking for things to do with the kids over Thanksgiving? How about making a coin launcher?
Watch the Coin Fly
This experiment teaches your child that air expands when you heat it up. Watch their delight when the coin flies away from the bottle. Why does this happen? As you freeze the bottle, the pressure inside the bottle drops, but is still the same outside. The pressure outside the bottle crushes the bottle until the pressures equalize. When you remove the bottle from the freezer and heat up the air again, the bottle pushes outwards to yet again equalize the pressure. The pressure inside the bottle builds up until the coin sealing the top is pushed upwards.
What You Need:
- An empty plastic soda bottle
- A large coin
- Some paper tissue
- A freezer
What You Do:
- Put the lid on your bottle, and then put it in the freezer for half an hour or so.
- Have a look at it – has it shrunk?
- Open the bottle while it is still in the freezer so it doesn't warm up.
- Cover the coin in a layer of wet tissue.
- Place the coin on the bottle with the tissue between the coin and the top of the bottle. Make sure it’s sealed properly.
- Leave the bottle for another half an hour until the tissue freezes
- Take the bottle out of the freezer point it away from you and warm it up using your hands.
- Wait and watch – see the coin fly?
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