Question

A boy sitting firmly over a rotating stool has his arms folded. If he stretches out his arms, his angular momentum about the axis of rotation will

• A. increase
• B. decrease
• C. remain unchanged
• D. first increase, then decrease

Answer 1

The correct option is C remain unchanged

Here, there is no external torque acting on the boy $+$ rotating stool system.

According to the conservation of angular momentum principle, when there is no external torque acting on the system, its angular momentum remains constant.

Hence, option $\left(C\right)$ is the correct answer.