Question

An object with a mass of `12` `kg` is moving at `9` `ms^-1` over a surface with a kinetic friction coefficient of `1`. How much power will it take to accelerate the object at `4` `ms^-2`?

Answer 1

Two forces are required: one to cause the acceleration, in accordance with Newton's Second Law, and one to overcome the friction. The total force `F=ma+mumg=165.6` `N`.

Explanation:

The force required to accelerate a `12` `kg` object at `4` `ms^-2` is given by:

`F=ma=12*4=48` `N`

The force required to overcome the friction is given by:

`F_"fric"=muF_"normal"` where `mu` is the friction coefficient

The normal force - the force acting between the object and the surface - is given by `F=mg`, so:

`F_"fric"=mumg=1*12*9.8=117.6` `N`

The total required force, then, is `48+117.6=165.6` `N`.