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Homework Help: Work of Electric Field Problem, can't find mistake!

  1. Feb 17, 2008 #1
    1. The problem statement, all variables and given/known data

    I posted the question on cramster at
    http://answerboard.cramster.com/physics- [Broken]...
    so you could see the picture.



    2. Relevant equations

    W = qV = kq1q2 / r

    3. The attempt at a solution

    I figure out A, B, and C, (which are the x component, y component, and the electric potential, but I can't figure out how to do part D, (which is the work to asseble the four charges). Please help! I tried to you W=qV, but that didn't work.

    My Answers were
    A) was 24.4
    B) was 77.96
    C) was 2.719x10^3

    Work done in assembling +6 uF and -6uF is zero

    Total work =kq1q2/r=9*10^9*8.2*16.4*10^-12/(47sin(60

    Total work =2.97*10^-2 J
     
    Last edited by a moderator: May 3, 2017
  2. jcsd
  3. Feb 17, 2008 #2
    The link was

    http://answerboard.cramster.com/physics-topic-5-189871-0.aspx [Broken]

    sorry
     
    Last edited by a moderator: May 3, 2017
  4. Feb 17, 2008 #3
    Wait, should I calculate each PE separately and then add them together? Would there be 6 different PEs?
     
  5. Feb 17, 2008 #4
    Figured it out....
     
  6. Feb 17, 2008 #5
    Upon brief inspection, What I would do is use the formula V= kQ/R for each point in relation to P. Then you can add these based on the sign of the charge to solve for W=qV. Give that a try.
     
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