Marvin and Milo

Explore physics the exciting way, by trying out a simple and fun experiment. This month, Spinning Seat Don't forget to check back next month for the next edition...

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What you need


A swivel chair

Two heavy food cans




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.

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.

The chair will spin much faster!

Results & 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.


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