A disk rotates about its central axis starting from rest and accelerates with constant angular acceleration. At one time it is rotating at 5.5 rad/s; 70 radians later, its angular speed is 15 rad/s. Calculate
(a) the angular acceleration (rad/s2),
(b) the time required to complete the 70 radians,
(c) the time required to reach the5.5 rad/s angular speed, and
(d) the number of radians from rest until the time the disk reaches the 5.5 rad/s angular speed.