A 2000 kg car accelerates from rest to a velocity of 20 m/s in 10 seconds.The power of the engine during this acceleration is
A) 50 kW.
B) 40 kW.
C) 30 kW.
D) 20 kW.
E) 10 kW.

Question

Quizplus · Accepted Answer

We can use the formula for power:
Power = Work/Time
The work done on the car is equal to the change in kinetic energy (1/2mv^2) from rest to a velocity of 20 m/s:
Work = (1/2)(2000 kg)(20 m/s)^2 = 400,000 J
The time taken for the car to reach 20 m/s is given as 10 seconds.
Hence, Power = 400,000 J /10 s = 40,000 W = 40 kW.

Therefore, the correct answer is B) 40 kW.

A 2000 Kg Car Accelerates from Rest to a Velocity