# Electric potential energy and displacement

1. Aug 7, 2006

### prolong199

could someone please lead me in the right direction with this question. I am confused about the time varying force in determining the work done

A time-varying force acts on a 5 kg mass yielding a displacement
x = 5t - 8t2 (x in m). The work done by the force between the times
t = 0 and t = 5s, is

thanks.

2. Aug 7, 2006

### Pseudo Statistic

You're missing a bit of information here; are you sure you're given nothing about the force?

3. Aug 7, 2006

### prolong199

thats what im thinking, it says a time varying force, but you can work out the force with regard to mass and acceleration fro the displacement function. So to answer your question, there is no other information provided for the question.

4. Aug 8, 2006

### ehild

You are right, you can get both velocity and acceleration so the force too, from x(t). The work between two points is the line integral of the force, but it can be calculated as the time integral of the power P=F*v in the given time interval.

ehild