Calculate the moment of inertia of a rectangular frame formed by uniform rods having mass `m` each as shown in about an axis passing through its centre and perpendicular to the plane of frame. Also find moment of inertia about an axis passing through `PQ` ?

Explanation

a. For calculation of the moment of inertia about centre, use parallel axis theorem
`I=2[(Ml^(2))/12+m(b/2)^(2)]+2[(mb^(2))/12+m(l/2)^(2)]`
b. Hence, we can also use parallel axis theorem
`I_(PQ)=2((mb)/3)^(2)+mb^(2)=5/3mb^(2)`