When a spinning ice skater pulls in his arms,he spins faster because
A)his angular momentum must be conserved,so reducing his radius must increase his speed of rotation.
B)there is less friction with the air.
C)there is less friction with the ice.
D)there exists an unbalanced reaction force.

Question

Quizplus · Accepted Answer

When the ice skater pulls in his arms, he reduces his radius of rotation. According to the law of conservation of angular momentum, his angular momentum must remain constant. Since the angular momentum is the product of the velocity and the radius of rotation, and the radius is now smaller, the velocity must increase to maintain the same angular momentum. Therefore, the skater spins faster.

When a Spinning Ice Skater Pulls in His Arms,he Spins