Question

A circular disc is rotating with angular velocity \(\omega\). If a man standing at the edge of the disc walks towards its centre then the angular velocity of the disc will

• A. decrease
• B. increase
• C. be halved
• D. not change

Hint:

This is similar to a spinning ice skater pulling arms inward to spin faster.

Answer 1

The Correct Option is B

Step 1: Concept:
Angular momentum is conserved when no external torque acts. \(L = I\omega = \text{constant}\).
Step 2: Explanation:
When man walks from edge to centre, moment of inertia \(I\) decreases (mass moves closer to axis).
Since \(L = I\omega\) is constant, if \(I\) decreases, \(\omega\) must increase.
Step 3: Conclusion:
Thus, angular velocity increases.