The 9-m steel beam is being hoisted from its horizontal postion by the two cables attached at A and B. If the initial angular accelerations of the hoisting drums are alpha1 = 0.5 ra/s^2 and alpha2 = 0.2 rad/s^2 in the directions, determine the correspondig angular acceleration alpha of teh beam, the acceleration of C, and the distance b from B to a point P on the beam centerline which has no acceleration