How Much Energy is Needed to Separate Two Atoms in a Vibrational State?

[PolyFX]

Homework Statement

This question seems like it should be really simple but I just can't figure it out.

This diagram is the potential energy curve for the interaction of two neutral atoms. the heavy solid horizontal line indicates the two atoms are in a vibrational state.

What minimum (positive) amount of energy must be supplied to cause these two atoms to separate?

Homework Equations

Kf + Uf = Ki + Ui == > Conservation of Energy?

The Attempt at a Solution

I got the previous parts of the question correct. It asked to find K, U and K+U at the point r1.

I really don't know how to solve this part however. I know that at the minimum (lowest) point on the potential energy graph the force between the two atoms is zero. This would mean that they are neither repelling nor attracting right? Do i need to incorporate this somehow in this question?

 

[Delphi51]

Likely "separate" means to move far apart where the interaction energy is zero. Just look at the graph and see how much must be added to bring the energy up to zero.