An electric car is powered by a 24 Volt battery pack and has a mass of 1600 kg. Its driveline consists of a DC motor whose efficiency is 70%. (i.e. 1 Joule of electrical power becomes 0.7 Joules of mechanical power.)

Suppose that as the car builds speed, the motor draws a constant 1000 Amps from the battery pack. How long will it take for the car to reach a speed of 60 mph ? You may neglect friction, aerodynamic drag, etc. and assume an ideal battery.