For the angular momentum of an object to be conserved (i.e., to not change), the
A) speed of the object must not change.
B) object must not be acted on by an internal torque (caused, for example, by the muscles in a skater's arms).
C) object must not be acted on by an outside torque.
D) size of the object must not change.

Question

Quizplus · Accepted Answer

Angular momentum is conserved in a system when there is no external torque acting on it. Internal forces, like those from a skater's muscles, do not affect the total angular momentum of a system, but external torques do. Changes in speed, size, or internal forces do not directly imply a change in angular momentum unless they result in an external torque.

For the Angular Momentum of an Object to Be Conserved