During the Spin-Dry Cycle of a Washing Machine, the Motor

Multiple Choice

During the spin-dry cycle of a washing machine, the motor slows from 90 rad/s to 30 rad/s while the turning the drum through an angle of 180 radians. What is the magnitude of the angular acceleration of the motor?

A) 64 rad/s²
B) 32 rad/s²
C) 10 rad/s²
D) 20 rad/s²
E) 1.0 rad/s²