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Coin in the balloon of death!

You will need:



  1. Squeeze a coin through the opening of the balloon. Make sure it goes all the way in
  2. Blow up the balloon and tie it.
  3. Hold the balloon as pictured.
  4. Swirl your bottom hand whilst keeping your top hand steady.
  5. The coin may bounce at first but you should find it start to scroll around the balloon.
  6. Stop moving your hands - you should find that the coin scrolls for 30 seconds. Why?
  7. Does the size of the coin matter? Try more than one coin!
  8. If you substitute the coin with a metal nut you will get a whirring sound as the edges of the nut causes the balloon rubber to vibrate (see for full experiment).
Balloon and coin experiment
Isaac Newton's first law of motion said that anything that is moving will want to keep moving in a straight line unless another force acts against it. This is called inertia.

The coin travels around the outside of the balloon because of inertia, i.e. it's trying to travel in a straight line but the curved surface of the balloon swings it around the corner. The coin continues to travel around the balloon until gravity and friction slows it down.

The same principle applies to the motor bike stunts in circular cages and rollercoasters!
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