Question

How much work would it take to horizontally accelerate an object with a mass of `4` `kg` to `3` `ms^-1` on a surface with a kinetic friction coefficient of `6`?

Answer 1

The weight force of a `4` `kg` mass is given by:

`F_w=mg=4xx9.8=39.2` `N`

The frictional force will be given by:

`F_"frict"=\muF_w=6xx39.2=235.2` `N`

Work will be done doing two things: overcoming friction and increasing the kinetic energy of the object. Let's take the kinetic energy first:

`E_k=1/2mv^2 = 1/2xx4xx3^2=18` `J`

Now the work done in overcoming the friction will be given by:

`W=F_"frict"s` where s is the distance traveled.

We don't know the distance it takes to accelerate the object from rest to `3` `ms^-1`.

And I'm stuck here. If we assume something we may be able to get it, but I'll have to leave that to some of my smarter colleagues.