Question

13. A car is moving along a straight horizontal road. The car has 1,6 MJ of kinetic

energy, The car accelerates for 20 s until the kinetic energy of the car increases to
2,5MJ, What is the minimum average power developed by the car engine for this
acceleration?
A. 45W
B. 205W
C.45 kW
D. 205 Kw


Answer 1

C.45 kW

Step-by-step explanation:

Given parameters:

Initial kinetic energy = 1.6MJ

Final kinetic energy = 2.5MJ

Time = 20s

Unknown:

Minimum average power developed = ?

Solution:

Power is rate at which work is done.

Here work done;

Work done = Final kinetic energy - Initial kinetic energy

Work done = 2.5MJ - 1.6MJ = 0.9MJ

Power =
`(work done)/(time)` =
`(0.9 x 10^(6) J)/(20)` = 45000W

This is therefore 45kW