Which device is using a motor?

a water heater creates heat energy from electric energy.

a waterfall rotates a waterwheel to turn an axle.

a body massager uses electric energy to move back and forth.

a solar charger creates electric energy from the sun.

Amachinist 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 96 rad/s. the wheel is run at that angular velocity for 40 s and then power is shut off. the wheel slows down uniformly at 1.5 rad/s2 until the wheel stops. in this situation, the time interval of deceleration is closest to: