angular acceleration/tangential velocity

[buffgilville]

Can someone please help me on how to solve this problem?

Two disks, A and B, are cemented together rotating with angular velocity a . The radius of the small disk B is 2/3 the radius of the larger disk A.

a) Calculate the ratio of the tangential velocity of a point on the rim of disk A to the tangential velocity of a point on the rim of disk B?

b) If the two disks in problem a have an angular velocity of w, calculate the ratio of the kinetic energy of disk A to the kinetic energy of disk B. Assume that each disk has a mass M.

[arildno]

a) How is, in general, tangential velocity at a radius "R" from the rotation axis coupled with angular velocity?
b) How is the kinetic energy of a rotating object related to the moment of inerta of the object with respect to the rotation axis and the angular velocity?
Assume that the mass distribution is equal for both disks.
(Use, for example, that each disk has a constant density in your calculations.)