Question

Two masses each of mass $M$ are attached to the end of a rigid massless rod of length $L$. The moment of inertia of the system about an axis passing through centre of mass and perpendicular to its length is

• A. $\frac{ML^2}{4}$
• B. $\frac{ML^2}{2}$
• C. $ ML^2$
• D. $ 2ML^2$

Answer 1

Answer: (B)

The moment of inertia of the system about the given axis is

$I = M (\frac{L}{M})^2 + M (\frac{L}{2})^2$
$ = \frac{ML^2}{4} + \frac{ML^2}{4} = \frac{ML^2}{2}$