A firm wants to estimate the amount of frictional torque in the incurrent line of grindstones, so they can redesign them to be more energy efficient. To do this, they ask you to test the best-selling model, which is basically a disk shaped grindstone of mass 1.3 kilogram and radius 7.50 centimeter which operates at 720 rev/min. When the power is shut off, you time the grindstone and find it takes 32.3 second for it to stop rotating.
(a) Find the angular acceleration of the grindstone?
(in rad/s2)
(b) Find the frictional torque exerted on the grindstone?
(N*m)