Question

An object with a mass of `4 kg` is moving at `7 m/s` over a surface with a kinetic friction coefficient of `3`. How much power will it take to accelerate the object at #4 m/s^2?

Answer 1

`952 W`

Explanation:

Clearly,here certain amount of force(`F`) will be required to overcome the frictional force acting at the interface of the object and the surface and then will impart an acceleration(`a`) of `4m/s^2`

Now,here frictional force(`f`) acting is `mu×N` =`mu×mg` i.e `120 N` (`mu` is the coefficient of kinetic friction)

So, from equation of force,we can write,

`F-f=m×a`

Putting the values we get, `F=136 N`

Now,considering that,after application of this force for certain time,the object will attain a velocity(`v`) of `7 m/s` from rest.

So, power required = `F×v` i.e `952 W`