You have a grindstone (a disk) that is 76.0 kg, has a 0.400-m radius, and is turning at 79.0 rpm, and you press a steel axe against it with a radial force of 22.0 N.(a) Assuming the kinetic coefficient of friction between steel and stone is 0.30, calculate the angular acceleration (in rad/s2) of the grindstone. (Indicate the direction with the sign of your answer.)(b) How many turns (in rev) will the stone make before coming to rest?