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Homework Help: Show that this equation is inverse square

  1. Jun 12, 2016 #1
    1. The problem statement, all variables and given/known data
    F = k(Q2*Q1)/(r^2)

    2. Relevant equations

    3. The attempt at a solution
    I asked my teacher and he said that this is an inverse square law. Didn't say anything else. He also mentioned k is constant.

    I assume i can plug in random values and see if there is a pattern... k=1 for all
    Set 1, q1 = 2, q2 = 4, r = 5
    F1 = 8/25
    Set 2, q1 = 1 q2 = 5, r = 4
    F2 = 5/16
    I plugged in random values but i don't really get it.
    What is inverse of what? I see that the r is squared and its below the kq1q2. I'm stuck.

    Any advice is appreciated.
  2. jcsd
  3. Jun 12, 2016 #2


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    This function is dependent on the inverse squared of r, which is usually the distance between the locations of Q1 and Q2.
  4. Jun 12, 2016 #3


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    What RUber said . ...

    So, pick values for Q1 and Q2 and stay with those. Then plug-in various values for r.
  5. Jun 12, 2016 #4
    Thank you so, r is the only value that is changing?
  6. Jun 12, 2016 #5

    Ray Vickson

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  7. Jun 12, 2016 #6
    Thank you, Yeah i googled it but thought the Q's changed as well. So it didn't make sense. Sometimes i need someone to explain it to me like im 5.
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