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A skater pulling her arms in reduces her rotational inertia, so her angular velocity must:
ADecrease
BStay fixed
CReach zero
DIncrease
Answer & Solution
Correct answer: D. Increase
1. Angular momentum is conserved while inertia changes.
2. Rotational inertia depends on the distribution of mass within the system.
3. Changes in radius change that inertia.
4. They change angular velocity for a given angular momentum.
5. The skater spins faster and faster by pulling her arms in, so angular velocity increases.
_Source: OpenStax College Physics for AP Courses 2e (CC BY 4.0), Ch 10 'Rotational Motion and Angular Momentum', sections 10.1-10.7_
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