Consider a situation where a skater pulls her arms inward, causing her rotation rate to speed up.
Angular momentum is conserved.

Question

Consider a situation where a skater pulls her arms inward, causing her rotation rate to speed up. 
Angular momentum is conserved.

Quizplus · Accepted Answer

According to the law of conservation of angular momentum, when there are no external torques acting on a system, the total angular momentum of the system remains constant. In this situation, the skater is changing her moment of inertia by pulling her arms inward, but since there are no external torques acting on the system, the total angular momentum of the skater remains conserved. As a result, the skater's rotation rate will increase as her moment of inertia decreases.

Consider a Situation Where a Skater Pulls Her Arms Inward