A car has a mass of 2,000 kg and travels at 20.0 m/s. If the drag force is 100 N, then the power the engines have to provide to keep moving at constant speed is
A) 2.0 kW.
B) 2.9 kW.
C) 3.4 kW.
D) 3.9 kW.
E) 4.2 kW.

Question

Quizplus · Accepted Answer

Power is the rate at which work is done. In this case, the work done is the force applied to the car multiplied by the distance traveled. The force applied is the drag force, which is 100 N. The distance traveled is the speed of the car multiplied by the time it takes to travel that distance. The time it takes to travel that distance is not given, so we cannot calculate the power directly. However, we can use the fact that the car is traveling at a constant speed to determine that the power provided by the engines must be equal to the drag force multiplied by the speed of the car. Therefore, the power provided by the engines is 100 N * 20.0 m/s = 2.0 kW.

A Car Has a Mass of 2,000 Kg and Travels