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Homework Help: Coulomb's Law and Simple Harmonic Motion

  1. Sep 28, 2010 #1
    1. The problem statement, all variables and given/known data
    Two positive charges +Q are affixed rigidly to the x axis one at x = -d and the other at x = +d. A third charge +q of mass mwhich is constrained to move only in the x axis is displaced from th eorigin by a small distance s << d and then released from rest. Show that q+ will execute simple harmonic motion and determine the oscillation period T.

    2. Relevant equations
    Coulomb's Law F=kQ1Q2/r2
    *possibly something else to relate this to SHM*

    3. The attempt at a solution
    I found the force from coulomb's law, F= -4kQqs/d3
    but i really don't know how to relate this to SHM so i can derive an equation for period.
  2. jcsd
  3. Sep 28, 2010 #2


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    Compare your expression for the force with the force exerted by a spring in a mass. How is the spring force related to the displacement of the mass from the equilibrium position?
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