Car A of mass 1000 kg moves on a horizontal straight road with speed `36kmh^(-1)`. If the force resisting the motion is 100 N, then find the power of the engine.
Now, after covering 200 m distance, car A collides with a stationary car B of same mass and becomes stationary. As a result car B start moving on the horizontal road, then what would be the speed of car B just after the collision? (The engine of car B is off.)

Answer

`1000W. 10ms^(-1)`

Explanation

Mass `(m)_(A)=(m)_(B)=1000kg`
Frictional force = 100 N
Power of engine of car A,
`P=Fv`
`=100xx10(because v=10ms^(-1))`
`=1000W`
Using the law of conservation of momentum,
`m_(A)u_(A)+m_(B)u_(B)=m_(A)v_(A)+m_(B)v_(B)`
`(1000xx10)+(1000xx0)=(1000xx0)+(1000xxv_(B))`
`therefore v_(B)=10ms^(-1)`