A Machinist Turns on the Power to a Grinding Wheel

Multiple Choice

A machinist turns on the power to a grinding wheel at time t = 0 s.The wheel accelerates uniformly from rest for 10 s and reaches the operating angular speed of
The wheel is run at that angular speed for 30 s and then power is shut off.The wheel slows down uniformly at
Until the wheel stops.In this situation,what is the angular acceleration of the wheel between
And

A) 3.8 rad/
B) 4.6 rad/
C) 5.3 rad/
D) 6.1 rad/
E) 6.8 rad/