The massive grinder for wood-pulp in a newsprint paper factory, which can render about a half tonne of wood into a thin soup in less than a minute, is essentially a stone cylinder of radius 0.650 m and mass about 5.00 Tonnes. An enormous motor spins this cylinder on its axis while hydraulic cylinders press the pocket of wood against its rim. A typical rotational speed for the motor is 84.0 rpm (rotations per minute). Suppose that while the paper plant is in full operation there is a power outage due to ice-storm.
i) How much energy (in J) is available to grind wood from rotational energy of the grinding wheel?
ii) If the grinding wheel comes to rest in 90.0 ms what is the tangential force (in N) that wood presents to grinding wheel if this force is constant during the slowing down?