Answer:
a)
was the angular acceleration of the grinding wheel.
b)800 revolutions has made by the wheel during the time it was coming to rest
Explanation:
Initial angular velocity of grinding wheel
= 20.0 rps
Final angular velocity of grinding wheel
= 0.0 rps
Time taken by wheel to come to rest = t = 80.0 s
a) Angular acceleration of the wheel = 


revolutions per second square

was the angular acceleration of the grinding wheel.
b) Initial angular velocity of grinding wheel
= 20.0 rps

Number of revolution before coming to rest = 



Number of revolution = 
800 revolutions has made by the wheel during the time it was coming to rest