# Work and Kinetic Energy

1. Sep 13, 2010

### mohabitar

That becomes:

The question is, why? In general calc, the integral of dx is just x, right? So why does that integral become delta x? Whats the logic behind that?

2. Sep 13, 2010

### w3390

Yes. The integral of dx is x. Since it is a definite integral, you must evaluate x from Xo to Xf. Therefore, you will have F[Xf - Xo] otherwise known as F*delta(x).

3. Sep 13, 2010

### mohabitar

Ahhh gotcha, thanks!