STANDARD Physics Conservation of Angular Momentum MCQ Question
A ballet dancer, dancing on a smooth floor is spinning about a vertical axis with her arms folded with an angular velocity of 20 rad/s. When she stretches her arms fully, the spinning speed decreases to 10 rad/s. If I is the initial moment of inertia of the dancer, the new moment of inertia is
2I
3I
I/2
I/3
Correct Answer
Detailed Explanation
Angular momentum is conserved. Initial angular momentum = Final angular momentum. Therefore, I × 20 = I' × 10, where I' is the new moment of inertia. Solving gives I' = 2I.
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