alleryStart learning →A merry-go-round is a uniform disk of mass 50.0 kg and radius 1.50 m. What is its moment of inertia about the central vertical axis?
A112 kg m^2
B37.5 kg m^2
C56.3 kg m^2
D28.1 kg m^2
Answer & Solution
Correct answer: C. 56.3 kg m^2
1. For a solid disk turning about its central axis, I = one half M R squared.
2. Here M = 50.0 kg and R = 1.50 m, so R squared = 2.25 m^2.
3. Substituting, I = (0.500)(50.0 kg)(2.25 m^2).
4. That gives I = 56.3 kg m^2.
5. Dropping the factor of one half gives 112 kg m^2, which is the hoop value instead.
_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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