Question

If a gymnast, sitting on a rotating stool, with his arms outstretched, suddenly lowers his arms

• A. The angular velocity decreases
• B. His moment of inertia decreases
• C. The angular velocity remains constant
• D. The angular momentum increases

Answer 1

The correct option is B His moment of inertia decreases

When the gymnast lower his arms, the distribution of mass changes about the axis of rotation. The mass comes more near to the axis and thus the moment of inertia of rotating system is reduced.