A car of mass one metric ton travels along a horizontal straight road with its engine working at a constant rate of 20kW. The resistance to motion of the card is 600N. Find the acceleration of the car at an instant, when its speed is 25 `m//s`

Explanation

Here, `m=1` metric ton = 1000 kg
Power of engine, `P=20 Kw=20000 W`
speed of car, `v=25m//s`
If F is the driving force of the car engine, then from `P=Fv`
`F=(P)/(v)=(20000)/(25)=800N`
As the car experiences resistance to motion `(f)=600N`, therefore net driving forces on the car engine,
`F^(')=F-f=800-600=200N`
If a is acceleration of the car, then
`a=(F^('))/(m)=(200)/(1000)=0.2m//s^(2)`