A shaft is turning at 65 rad/s at time t=0. Thereafter, its angular acceleration is given by α = -10 rad/s2 - 5t rad/s3 , where t is the elapsed time. (a) Find its angular speed at t=3 s. (b) How far does it turn in these 3s?

Definition Definition Rate of change of angular velocity. Angular acceleration indicates how fast the angular velocity changes over time. It is a vector quantity and has both magnitude and direction. Magnitude is represented by the length of the vector and direction is represented by the right-hand thumb rule. An angular acceleration vector will be always perpendicular to the plane of rotation. Angular acceleration is generally denoted by the Greek letter α and its SI unit is rad/s 2 .