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Relatively simple vectors question, but no numbers...

  1. May 23, 2016 #1
    The unit right now is electrostatics, but this question is really just vectors, nothing to do with charges or anything... anyways here is the info:

    1. The problem statement, all variables and given/known data

    Three identical point charges, A, B, and C are located as shown here:

    M9bYJ9L.png

    The force A-on-C is the same as the force B-on-C. What is the net force on C?

    2. Relevant equations

    I think the only equation I need is the superposition of force principle:
    FnetC = FAonC + FBonC

    3. The attempt at a solution

    Breaking into components (not allowed to use cosine law for some reason):

    I know X-axis force is 0 as the 2 forces cancel out (since they are both equal and in opposite directions).

    FnetCY = FAonC * cos(45) + FBonC * cos(45)

    Not sure what else I can do though...

    EDIT: I messed around with the 1-1-sqrt(2) triangle and I'm not sure if this is right, but is (2/sqrt(2)) * FAonC the right answer?

    EDIT 2: Yes, that's the right answer, but sqrt(2) * FAonC is also right.

    Because guess what, 2 divided by squareroot(2) is THE SAME THING AS squareroot(2)...
     
    Last edited: May 23, 2016
  2. jcsd
  3. May 23, 2016 #2
    seems okay to me
     
  4. May 23, 2016 #3
    assuming the charges on the charges on the corners A and B are all the same polarity
     
  5. May 23, 2016 #4
    Yeah they are all identical.

    How would I use the 1-1-squareroot2 triangle to simplify it more? I'm not sure how to do that part too well.
     
  6. May 23, 2016 #5
    replace your cos45 statement with the equivalent ratio
     
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