A drum of 4-in. radius is attached to a disk of 8-in. radius. The disk and drum have a total weight of 10 lb and combined radius of gyration of 6 in. A cord is attached as shown and pulled with a force P of magnitude 5 lb. Knowing that the disk rolls without sliding, determine

(a) The angular acceleration of the disk and the acceleration of G,

(b) The minimum value of the coefficient of static friction compatible with this motion.