In my mechanics lecture notes, it is written that, for a force $F$,
To be conservative, $F$ must be a function of position only: forces that depend on velocity, time, etc. cannot be conservative.
How do I go about proving, mathematically, such statement?
In the case of a drag force (like air resistance), I know that we get energy dissipation and therefore such force cannot be conservative. How should I argue in a more general scenario?