you have a grindstone (a disk) that is 89.0 kg, has a 0.400-m radius, and is turning at 75.0 rpm, and you press a steel axe against it with a radial force of 25.0 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.) rad/s2 (b) how many turns (in rev) will the stone make before coming to rest? rev