Weights and Wheels

A series of three blue wheels of different thicknesses sitting on a red table.

A wheel's rotational inertia changes when its mass is mostly located near the centre or near the rim.

How it works

Wheels spin differently, depending on whether mass is distributed around the rim, the centre, or evenly across the whole wheel.

Things to try or ask around the exhibit

  • How can you make this wheel spin longer?
  • Is it easier to spin the wheel when the masses are near the centre or near the rim?

Background

When the mass is located at the edge or rim of the wheel, it takes more effort to get the wheel spinning, but the wheel spins longer. This is due to rotational inertia.

Finding the science in your world

Wheels that have weighted rims are called flywheels. They are often used in machinery because the wheel spins with strong force to move pistons.