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Forces – Stomper Rocket


  • One plastic cup
  • One piece of cotton string, or twine
  • A paperclip
  • A scissors
  • And a small bowl of water


1. Place a small hole in the top of the cup, perhaps ask an adult to do this for you!

2. Cut out a length of cotton string or twine, I cut mine about 60 cm in length.

3. Tie one end of the string securely to the paperclip.

4. Thread your string through the top hole in the cup, just like this, so you end up with something that looks a bit like a bell.

5. Now for the fun part… dip the string into the bowl of water, to wet it, you can squeeze out any excess water.

6. Hold the cup up like this and pinch the string between your thumb and first finger and then pull down on the string like this.

Quite a funny sounds, isn’t it? And you should be able to change the sound a bit, just by changing how you pull on the string.

When you pull on the string you make it start to vibrate. Having a wet string increases the friction between the string and your fingers so it vibrates even more.
The string is attached to the paperclip and the cup, so they start to vibrate too.
The cup is full of air, which starts to vibrate and this amplifies the sound, so you get to make quite a big noise.

What you need:


Do it at home

Do it at Home