A dc motor is connected to a constant emf of 16.9 V. The resistance of its windings is 2.0 ?. At normal operating speed, the motor delivers 7.1 W of mechanical power. (a) What is the initial current drawn by the motor when it is first started up? (b) What current does it draw at normal operating speed? (c) What is the back emf induced in the windings at normal speed?