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

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