A Grinding Wheel Is Spinning at a Rate of 20

Short Answer

A grinding wheel is spinning at a rate of 20.0 revolutions per second. When the power to the grinder is turned off, the grinding wheel slows with constant angular acceleration and takes 80.0 s to come to a rest.
(a) What was the angular acceleration of the grinding wheel as it came to rest?
(b) How many rotations did the wheel make during the time it was coming to rest?