Forces and Motion

Potato Puncture

At home for 5-11 11-14

What you need

  • A raw baking potato
  • A new straw
  • A thick glove


  1. Hold the potato with the thumb and forefingers of a gloved hand. Don’t put your hand behind the potato!
  2. Make a fist with your other hand, grasping the straw firmly about two-thirds of the way up
  3. Use a fast, thrusting movement to force the straw into the potato

Results and Explanation

The straw should go in, but if you try to twist it in slowly, it doesn’t work.
The rim of the straw has a very small surface area, so you have a small amount of potato to displace and your sharp movement delivers a large force on it in a brief instant, which works much better than a slow twist.

These experiments have not been specifically safety tested for home use but we believe them to be safe if the instructions are followed. Adult supervision or direction is recommended as appropriate. All experiments are carried out at your own risk.


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