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 decreases and her angular speed increases.
B)her moment of inertia decreases and her angular speed decreases.
C)her moment of inertia increases and her angular speed increases.
D)her moment of inertia increases and her angular speed decreases.
E)her moment of inertia increases and her angular speed remains the same.

Question

Quizplus · Accepted Answer

When the person extends her arms, her moment of inertia increases as the mass is now distributed further away from the axis of rotation. As per the conservation of angular momentum, the angular velocity must decrease because the product of moment of inertia and angular velocity must remain constant. Therefore, the correct choice is D.

A Person Sits on a Freely Spinning Lab Stool That