Four particles each of mass m are kept at the four corners of a square of edge a. Find the moment of inertias of the system about a line perpendicular to the plane of the square and passing through the centre of the square.

Explanation

The perpendicular distance of every particle from the given line is `a// sqrt2` . The moment of inertia of one particle is, therefore, `m (a//sqrt2)^2 = 1/2 = ma^2`.
The moment of inertia of the system is,
therefore, ` 4 xx1/2 ma^2 = 2 ma^2`.