Physics
Conservation of Angular Momentum in Figure Skating
Quick fact
Figure skaters can control their spin speed by pulling in or extending their arms, which changes their moment of inertia.
Why this is interesting
Have you ever watched a figure skater spin so fast they look like a blur? How do they make themselves spin faster or slower without touching the ice?
Read the full explanation
Understanding Conservation of Angular Momentum in Figure Skating
When a figure skater spins on the ice, they're using angular momentum. Angular momentum is like the spinning version of linear motion. If no external forces act on them, their total angular momentum stays constant. By pulling their arms in, they reduce their size and spin faster; by extending their arms, they increase their size and slow down.
A deeper explanation
Angular momentum depends on two things: how much mass an object has (mass distribution) and how fast it's spinning (angular velocity). When a skater pulls their arms in, the moment of inertia decreases, but to conserve angular momentum, the angular speed must increase. This is why skaters spin faster when they pull in their limbs. The conservation of angular momentum explains how they can control their motion without any external force—just through changes in their body shape.