Lennard-Jones potential graph w/ attractive/repulsive force

[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.

 

[Chestermiller]

View attachment 54775

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.

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

 

[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)