Question

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

• A. increases
• B. decreases
• C. remains unchanged
• D. None of the above

Answer 1

The correct option is C remains unchanged

In this case Angular momentum $L$ is constant since no external torque acts

$L=1W$

But $I=M{R}^2$ increases as $R$ increases

So $W$ or the angular velocity dereases $L$ is constant.