Question

The moment of inertia of a solid disc made of thin metal of radius $R$ and mass $M$ about one of its diameters is given by $\frac{M{R}^2}{4}$. What will be the moment of inertia about this axis, if the disc is folded in half about this diameter?

• A. $\frac{M{R}^2}{8}$
• B. $\frac{M{R}^2}{2}$
• C. $\frac{M{R}^2}{4}$
• D. $M{R}^2$

Answer 1

Answer: (C)

As mass distribution in rotation about the diameter is same in both cases, moment of inertia also remains same in both cases.
$\therefore$ Moment of inertia (half folded disc)$=\frac{M{R}^2}{4}$