A person sits on a freely spinning lab stool that has no friction in its axle. When this person extends her arms,
A) her moment of inertia increases and her angular speed remains the same.
B) her moment of inertia increases and her angular speed decreases.
C) her moment of inertia decreases and her angular speed increases.
D) her moment of inertia increases and her angular speed increases.
E) her moment of inertia decreases and her angular speed decreases.

Question

Quizplus · Accepted Answer

When the person extends her arms, her moment of inertia increases because the mass distribution is farther from the axis of rotation. According to the conservation of angular momentum, if the moment of inertia increases, the angular speed must decrease to keep the angular momentum constant.

A Person Sits on a Freely Spinning Lab Stool That