Science Experiments

Which Thread Breaks? Using inertia to your advantage

Sun, 29th Jan 2012

Listen Now    Download as mp3 Part 1,2,3 from the show Are any viruses good for you?

What you Need


2 pieces of Cotton about 40cm long

A bottle

A small 250ml plastic bottle of water or drink

What to do

  • Tie both pieces of cotton to the neck of the bottle.
  • Tie the other end of one of the pieces onto something solid so the bottle will hang down.
  • Hold onto the other piece of cotton, and pull slowly. Where does the cotton break?
  • Repeat the experiment, but this time pull very quickly, where does the cotton break now?

What may happen

You should find that when you pull slowly the cotton breaks above the bottle, but rather surprisingly when you pull quickly it breaks below it.

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