Angular Momentum

The spinning skater

An interactive lesson with 6 steps, about 5 minutes: you predict, drag and solve, with instant feedback on every answer. It runs in your browser and needs JavaScript.

What you’ll learn

• Angular momentum $L = I\omega$ is conserved when there's no external torque.
• Reduce $I$ (pull the mass in) and you spin faster: skaters, divers, neutron stars.
• Rotation has its own versions of mass, force and momentum.

Steps

1. Arms in
2. Conservation of angular momentum
3. Spin up
4. Where does the energy come from?
5. Extra spin energy
6. Collapsing stars