alleryStart learning →The moment of inertia of a hoop about its axis is its total mass multiplied by:
ATwice the radius
BHalf the radius
CThe radius squared
DThe radius itself
Answer & Solution
Correct answer: C. The radius squared
1. A hoop is the one simple case where the calculation is immediate.
2. A hoop has all its mass at the same distance from its axis.
3. A hoop's moment of inertia around its axis is therefore its total mass times its radius squared.
4. The squared dependence is why moving mass outward raises rotational inertia so sharply.
_Source: OpenStax College Physics for AP(R) Courses 2e (CC BY 4.0), Ch 10 'Rotational Motion and Angular Momentum', sections 10.1-10.7_
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