Question

Moment of inertia of a circular wire of mass $M$ and radius $R$ about its diameter is :

• A. $M{R}^2/2$
• B. $M{R}^2$
• C. $2M{R}^2$
• D. $M{R}^2/4$

Answer 1

Answer: (A)

Moment of inertia of circular wire about its axis is $M{R}^2$, Consider two diameters $XX$ and $YY$ moment of inertia about any of this diameter is same let us say $I$.
From perpendicular axis theorem, $I+I=M{R}^2$
$I=\frac{M{R}^2}{2}$