Putting energy to work

We use energy to do work. Try making a simple toy that puts energy to work.

1. Push the rubber band through the hole in the middle of the cotton reel. Break the matchstick in half and push a piece through the loop of the rubber band. Tape the matchstick to the cotton reel, so that it cannot turn.

• An empty cotton reel
• A matchstick
• A rubber band
• A piece of sticky tape
• A round bead
• A pencil about 10 centimeters long
  
  

2. At the other end, pull the rubber band through the bead with an unbent paper clip, and then push the pencil through the loop. The rubber band should be holding everything together, so0 if it's too loose find another the right length.

3. Wind the pencil round ten times and let go of the cotton reel on a flat surface. What happens?


The rubber band makes the cotton reel move, but where did the energy of the rubber band come from? What difference does the number of turns in the band make?Try it with 20,30 or 40 turns. Does changing the length of the pencil make any difference?You could try making a bigger machine from an empty washing-up liquid bottle.