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Point Charges on Equilateral Triangle - Need Geometry Help

  1. Aug 29, 2011 #1
    1. The problem statement, all variables and given/known data
    http://www.ridemtl.com [Broken]


    2. Relevant equations
    F = k(q1q2/r^2)


    3. The attempt at a solution
    I know pretty much what to do for the problem, but I cannot get the right answer. I think my issue lies within what angles I am using for the components. Because it is an equilateral triangle, all angles within that triangle are 60 deg. But when I use 60 deg to calculate the components in the x & y directions, I can't come up with the right answer.

    F of 2 on 1 = 0.0579 N
    F of 3 on 1 = 0.0358 N

    x: 0.0579 cos 60 -i, 0.0358 cos 60 +i
    y: 0.0579 sin 60 -j, 0.0358 sin 60 -j

    Sum these together and use Pythagoras for overall magnitude
    The magnitude the above produces is 0.0818 N

    I am not getting the right answer. Thus I think my problem lies in the angles I am using. Can anyone shed some light?
     
    Last edited by a moderator: May 5, 2017
  2. jcsd
  3. Aug 29, 2011 #2

    PeterO

    User Avatar
    Homework Helper

    Nothing wrong with what you have written so far. Could be a problem with what you haven't written.

    I would have liked to see what you thought 0.0579 sin 60 was equal to, for example.

    I would then like to see how you thought the 0.0818 came about???
     
    Last edited by a moderator: May 5, 2017
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