
The formula to calculate the moment of inertia of a system of particles about a point can be written as
I=i=1∑nmiri2...(1)
where, mi is the mass of the ith particle situated at a distance ri from the point.
With reference to the above diagram, it can be written that the net moment of inertia of the system of particles is
I====ma2+ma2+m(2a)24ma24×1kg×(2m)216kgm2