Question

Two rings having the same radius and mass such that their centres are at a common point and perpendicular to each other. Find the moment of inertia of the system about an axis passing through the centre and perpendicular to the plane of one of the rings. ($M=$ mass of each ring and $R=$ radius )

Answer 1

Here two rings are perpendicular to each other such that their planes are perpendicular.

So if we take an axis perpendicular to plane of one ring then it will be diametrical axis of other then,

$I=M{R}^2+\frac{1}{2}M{R}^2$

$I=\frac{3}{2}M{R}^2$