A small electric car overcomes a 250-N friction force when traveling 35 km/h. The electric motor is powered by ten 12-V batteries connected in series and is coupled directly to the wheels whose diameters are 58 cm. The 290 armature coils are rectangular, 12 cm by 15 cm, and rotate in a 0.65-T magnetic field.
(a) How much current does the motor draw to produce the required torque?
(b) What is the back emf?
(c) How much power is dissipated in the coils?
(d) What percent of the input power is used to drive the car?