Conservation of Angular Momentum
Forces and Motion

Spinning Seat

At home for 5-11 11-14


What you need

  • A swivel chair
  • Two heavy food cans
  • Cushions

Instructions

  1. Sit an adult in the chair and ask them to hold a can in each hand with their arms stretched out at right angles. Put some cushions on the floor round them, for safety.
  2. Set the chair spinning. When it has reached a steady speed, ask them to quickly pull in their arms tight to their body, still holding the cans.
  3. The chair will spin much faster!

Results and Explanation

The chair, person and cans together have something called angular momentum, which depends on how fast they're spinning and how far out the cans are held.
As the angular momentum has to stay the same, tucking in your arms means the speed has to go up to compensate - so the chair spins faster.

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.

2021 IOP Awards

Teachers of Physics Award

Recognising and celebrating outstanding contributions to the field of physics education.

Learn more