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Homework Help: Find the electrostatic force

  1. Feb 27, 2015 #1
    1. The problem statement, all variables and given/known data
    We know that the magnitudes of the negative charge on the electron and the positive charge on the proton are equal. Suppose, however, that these magnitudes differed from each other by as little as 0.0001%. With what force would two copper pennies, placed 1.0 m apart, repel each other? Estimate any quantities you need that you do not know.

    2. Relevant equations
    F=kQ1Q2/r^2

    3. The attempt at a solution
    I do not know from where to start. I drew a picture of the charges. I do not know how to find the charge from 0.0001% condition. Can you help me please?
     
  2. jcsd
  3. Feb 27, 2015 #2

    gneill

    User Avatar

    Staff: Mentor

    You could start by estimating the numbers of protons and electrons in a penny. You may need to consult the periodic table...
     
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