Starting from rest, a disk rotates about its central axis with constant angular acceleration. In 8.0 s, it rotates 50 rad. (a) What was the angular acceleration during this time? (in radians/sec^2) (b) What was the average angular velocity? (in radians/sec) (c) What is the instantaneous angular velocity of the disk at the end of the 8.0 s? (in radians/sec) (d) Assuming that the acceleration does not change, through what additional angle will the disk turn during the next 4.0 s? (in radians)