Question

Determine the moment of Inertia of a uniform rectangular plate of mass m, side 'b' and 'l" about an axis passing through the edge 'b' and in the plane of the plate.

Answer 1

Each section of dm mass rod in the rectangular plate has moment of inertia about an axis passing through

edge 'b' $dI=\frac{dm{l}^2}{3}$
So $I=\int dI=\frac{l^2}{3}\int dm=\frac{M{l}^2}{3}$