A 600 V dc shunt motor drives a 60 kW load at 900 rpm. The shunt field resistance is 100 \Omega and the armature resistance is 0.16 \Omega . If the motor efficiency at the load is 85%, determine
(a) the rotational loss
(b) the no load armature current and speed. Also find speed regulation
(c) the armature current for electromagnetic torque of 600 Nm