An ice skater performs a pirouette (a fast spin) by pulling in his outstretched arms close to his body. What happens to his angular momentum about the axis of rotation?
A) It changes, but it is impossible to tell which way.
B) It does not change.
C) It increases.
D) It decreases.

Question

Quizplus · Accepted Answer

The angular momentum of the ice skater about the axis of rotation does not change when he pulls his arms in because of the conservation of angular momentum. This principle states that if no external torque acts on a system, the total angular momentum of the system remains constant.

An Ice Skater Performs a Pirouette (A Fast Spin) by Pulling