?explanations needed, thanks. A wheel of radius a, with its mass concentrated on the rim, is…

?explanations needed, thanks.
A wheel of radius a, with its mass concentrated on the rim, is rolling with velocity v round a circle of radius (R >> a), maintaining a constant inclination alpha to the vertical. Show that v = a omega = R Ohm, where omega is the angular velocity of the wheel about its axis, and Ohm (