Question

The moment of inertia of a disc of mass $M$ and radius $R$ about an axis, which is tangential to the circumference of the disc and parallel to its diameter, is

• A. $\frac{3}{2}M{R}^2$
• B. $\frac{2}{3}M{R}^2$
• C. $\frac{5}{4}M{R}^2$
• D. $\frac{4}{5}M{R}^2$

Answer 1

Answer: (C)

Moment of inertia of disc about its diameter is $I_d=\frac{1}{4}M{R}^2$
MI of disc about a tangent passing through rim and in the plane of disc is
$I=I_G+M{R}^2=\frac{1}{4}M{R}^2+M{R}^2=\frac{5}{4}M{R}^2$