alleryStart learning →What is the moment of inertia of a hoop about its own central axis?
AM R squared divided by two
BM R squared divided by three
CTwo M R squared over five
DM R squared, with no fraction
Answer & Solution
Correct answer: D. M R squared, with no fraction
1. Moment of inertia is the sum of m r squared over all the mass of the body.
2. A hoop has all of its mass at the same distance R from the axis.
3. The sum then factors to M R squared with no fraction in front.
4. Half M R squared belongs to a solid disk, where much of the mass sits nearer the axis.
_Source: OpenStax College Physics (CC BY 4.0), Ch 10 "Rotational Motion and Angular Momentum", section 10.3 Dynamics of Rotational Motion: Rotational Inertia_
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