Question

A rapidly spinning ice skater has her hands close to her body. She then extends her arms horizontally. What change, if any, will there be in the following quantities related to her motion? Moment of Inertia, Angular velocity, Angular Momentum. Ignoring friction, tell whether each would increase, decrease, or remain constant.

Answer 1

Solution) When ice skater draws her arms and a leg inward ,she reduces the distance between axis of rotation and some of her mass , reducing her moment of inertia since angular momentum is conserved her rotational velocity increases to compensate .

So moment of inertia and angular velocity changes but angular momentum remains constant

So to conserve angular momentum if moment of inertia increases angular velocity decreases and if moment of inertia decreases angular velocity increases .