The uniform disk shown, of mass m and radius r, rotates counterclockwise. Its center G is...

The uniform disk shown, of mass m and radius r, rotates counterclockwise. Its center G is constrained to move in a slot cut in the vertical member AB and a horizontal force P is applied at B to maintain contact at D between the disk and the vertical wall. The disk moves downward under the influence of gravity and the friction at D. Denoting by µk the coefficient of kinetic friction between the disk and the wall and neglecting friction in the vertical slot, determine  (a) the angular acceleration of the disk, (b) the acceleration of the center C of the disk.