Conservation of angular momentum

A man holding onto two weights with his arms outstretched stands on a platform that is freely rotating about a frictionless axle. When he moves his arms close to his body, his angular velocity increases.

Which of the following best describes why the man’s angular velocity increased?

(Choice A)
The moment of inertia decreased, resulting in an increase in angular momentum.
(Choice B)
The moment of inertia decreased while the angular momentum remained constant.
(Choice C)
The moment of inertia increased, resulting in an increase in angular momentum.
(Choice D)
The moment of inertia increased while the angular momentum remained constant.

AP®︎/College Physics 1

Course: AP®︎/College Physics 1 > Unit 5

Problem