# Non Conservative Forces

1. Jun 21, 2013

### andyrk

Can you tell me more about Non Conservative Forces? In non conservative forces like friction work done is dependent on the path that we take to reach one position to the other position but how? And why does potential energy have a meaning only for conservative force field and not non-conservative force field?

2. Jun 21, 2013

### voko

Path dependence is pretty much a definition of a non-conservative force. And path dependence is equivalent with absence of potential energy for the force. The equivalence is rigorously proved in calculus.

3. Jun 21, 2013

### andyrk

How is path dependence equivalent to undefined potential energy?

4. Jun 21, 2013

### voko

Like I said: this is studied in calculus. If you have studied multivariate calculus and path integrals, you should know. If you have not, I won't be able to explain that in a post on a forum. Sorry.

5. Jun 21, 2013

### andyrk

Is the calculus part you are talking about made for the high school level ?

6. Jun 22, 2013

### voko

One part of the equivalence is rather trivial, though. If force F has potential energy U(x), then the work of force between x = a and x = b is U(a) - U(b), which is independent of the path.

The proof of the other part is more involved.