# I Why do conservative forces MUST depend on the position?

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1. May 6, 2016

### svletana

...Or do they? I read on a book a few years ago that you can spot a conservative force seeing if it depends on the position or not. That means a non conservative force doesn't depend on the position. What is the physical reason for the relationship between a force being conservative and the function depending on the position?

2. May 6, 2016

### mfig

First off, you would be greatly served to use more precision when asking science questions. For example, when you say,

What "the function" are you talking about? "The function" could be a lot of things. Be specific.

Are you talking about the work done by a conservative force being path independent? If so, then you are referring to a definition of conservative forces. It is akin to asking, "Why is pi the ratio of the circumference of a circle to its diameter?" Pi is defined as this ratio; that is why it is this ratio! Similarly, a conservative force just is a force for which the work done along a closed path is zero. That is what the term means.

3. May 7, 2016

### A.T.

A uniform force field doesn't depend on position but is conservative.

4. May 7, 2016

### ehild

No, conservative forces need not depend on position, but they can depend only on position. A constant force is conservative.
A force dependent on time or velocity is not conservative.