An electric car is designed to run off a bank of 15-V batteries with total energy storage of 2.1 × 10⁷ J.If the electric motor draws 4 200 W in moving the car at a steady speed of 14 m/s,how far will the car go before it is "out of juice?"

Question

Quizplus · Accepted Answer

The total energy available is 2.1 × 10^7 J. The power drawn by the motor is 4,200 W, which means it uses 4,200 J/s. The time the car can run is 2.1 × 10^7 J / 4,200 J/s = 5,000 s. At a speed of 14 m/s, the distance covered is 14 m/s * 5,000 s = 70,000 m, which is 70 km.

An Electric Car Is Designed to Run Off a Bank