Question

A disc of mass $M$ and radius $R$ has a concentric hole of radius $\dfrac{R}{2}$. Its moment of inertia about an axis passing through its center and perpendicular to its plane is:

• A. $\dfrac{15}{32}MR^2$
• B. $\dfrac{13}{32}MR^2$
• C. $\dfrac{5}{16}MR^2$
• D. $\dfrac{3}{8}MR^2$

Hint:

For an annular disc: \[ I = \frac{1}{2}M(R_1^2 + R_2^2) \] Always check whether the given mass belongs to the original disc or the remaining annular disc.

Answer 1

The Correct Option is A