Question

Two identical concentric rings each of mass $m$ and radius $R$ are placed perpendicularly. What is the moment of inertia about axis of one of the rings

• A. $\frac{3}{2}MR^2$
• B. $2MR^2$
• C. $3MR^2$
• D. $\frac{1}{4}MR^2$

Answer 1

Answer: (A)

$\frac{3}{2}MR^2$

Answer 2

Since the axis of two rings are also perpendicular to each other, therefore applying the theorem of perpendicular axes
$I=M R^{2}+\frac{1}{2} M R^{2}$
$\frac{3}{2} M R^{2}$