# Lennard-Jones potential graph w/ attractive/repulsive force

1. Jan 15, 2013

### destroyer130

Based on this and the equation F = -d$\Phi$/dr. I can't visualize what is positive and negative force direction (what is positive direction). So is that just mean whenever the force between 2 molecules (+), it's repulsive; and whenever it's (-), it's attractive? Thanks for checking this out.

2. Feb 15, 2013

### Staff: Mentor

What this graph is telling you is that, if the two molecules are farther apart than rm, the force between them is attractive, but if they are closer together than this, the force is repulsive.

3. Mar 25, 2013

### davidyanni10

What Chestermiller said.

I just want to point out that with the equation you posted the force is attractive when it is positive and repulsive when negative (not the other way around) (When the slope of the potential curve is negative the force is positive)