A machinist turns the power on to a grinding wheel, at rest, at time t = 0 s. The wheel accelerates uniformly for 10 s and reaches the operating angular velocity of 66 rad/s. The wheel is run at that angular velocity for 37 s and then power is shut off. The wheel slows down uniformly at 1.2 rad/s2 until the wheel stops. In this situation, the angular acceleration of the wheel between t = 0 s and t = 10 s is closest to: