Rigid Body Dynamics: MOI — Compound MCQ

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MOI — CompoundHardQuestion 30341

Question

A uniform disc of original mass M and radius R has a concentric circular hole of radius R/2 cut from it. Its MOI about the central axis is:

15MR²/32

The removed disc has mass $M/4$ and MOI $\frac12(M/4)(R/2)^2=MR^2/32$ . Subtracting it from the original $MR^2/2$ gives $15MR^2/32$ .