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Homework Help: Potential Energy of Two Atoms?

  1. Oct 17, 2013 #1
    1. The problem statement, all variables and given/known data
    The potential energy of two atoms separated by a distance r may be written as:

    U(r) = 4Uatomic * [(r0/r)12 - (r0/r)6]

    >Given r0 = 4.0 Ao and Uatomic = -0.012795 eV, what is the distance at which there is no net force between the atoms? Express your answer in terms of Ao.

    >What is the potential energy at the position where the net force is 0 N? Express your answer in terms of eV.

    2. Relevant equations
    The above equation.

    3. The attempt at a solution
    I tried using Coulomb's Law, but I don't know the charges so it's not very helpful. Finding the total energy is also not relevant since I don't know mass or velocity. I'm pretty stuck here. I know once I find the first part I can find the second part easily, but I feel like I'm overlooking something simple for the first part of the question.
  2. jcsd
  3. Oct 17, 2013 #2

    Doc Al

    User Avatar

    Staff: Mentor

    Hint: What's the relationship between force and the potential function? (Use calculus.)
  4. Oct 17, 2013 #3
    F = -dU/dr :) I tried it and it worked! Thanks for the hint!
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