A drum of radius R and mass M, rolls down without slipping along an inclined plane of angle $$\theta $$. The frictional force

The moment of inertia of a uniform circular disc of radius R and mass M about an axis passing from the edge of the disc and normal to the disc is

The ratio of the radii of gyration of a circular disc about a tangential axis in the plane of the disc and of a circular ring of the same radius about a tangential axes in the plane of the ring is

A round disc of moment of inertia $$I$$₂ about its axis perpendicular to its plane and passing through its centre is placed over another disc of moment of inertia $$I$$₁ rotating with an angular velocity $$\omega $$ about the same axis. The final angular velocity of the combination of discs is