A large reel of paper installed at the end of a paper machinehas a diameter of 1.8m, a length of 5.6m and a moment of inertia of4500 kg-m2. It is driven by a directly coupled,variable-speed DC motor turning at 120 rpm. The paper is kept undera constant tension of 6000 N.
(a) Calculate the power (in hp) required from the motor toturn the reel at 120 rpm.
(b) If the speed has to be raised from 120 rpm to 160 rpm in 5seconds, calculate the torque that the motor must develop duringthis interval.
(c) Calculate the required motor power after it has reached160 rpm.