A mass m is fixed to a given point on the edge of a wheel of radius

Question:

A mass m is fixed to a given point on the edge of a wheel of radius R. The heel is massless, except for a mass M located at its center (see Fig.). The wheel rolls without slipping on a horizontal table. Find the equation of motion for the angle through which the wheel rolls. For the case where the heel undergoes small oscillations, find thefrequency.