Question

Physics Work and Energy Question?

A 1000 kg car is moving along a straight road at `25 ms^-1`. A net force of 200 N acts in a forward direction for a distance of 1.0 km. What is the work done on the car by the net force?

Answer 1

`W = Fx = 200* 1000 = 2*10^5 " J"`

Answer 2

`2*10^5 \ "J"=200,000 \ "J"`

Explanation:

Work done is given by the equation:

`W=F*d`

where:

• `W` is the work done in joules

• `F` is the force applied in newtons

• `d` is the distance moved in meters

We got: `d=1 \ "km"`. Let's convert that to meters. We know that one kilometer is equal to `1000` meters.

So, we get:

`d=1color(red)cancelcolor(black)"km"*(1000 \ "m")/(color(red)cancelcolor(black)"km")=1000 \ "m"`

So the work done is:

`W=200 \ "N"*1000 \ "m"`

`=200,000 \ "N m"`

`=200,000 \ "J" \ (because 1 \ "N m"-=1 \ "J")`