Question

If all of the mass, M of the compound pendulum (shown in figure 1) is concentrated at the centre
of mass G, the compound pendulum turns out to be a simple pendulum. Just think that the point
of oscillation, O and the centre of mass G are connected by a mass-less, inextensible, flexible
string. OG=D (same as earlier). Now what is the moment of inertia, I of this simple pendulum
about point O?