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Homework Help: 3 Styrafoam Balls Repelling

  1. Feb 5, 2009 #1
    1. The problem statement, all variables and given/known data
    Three identical small Styrofoam balls (m = 1.84 g) are suspended from a fixed point by three nonconducting threads, each with a length of 46.5 cm and with negligible mass. At equilibrium the three balls form an equilateral triangle with sides of 30.0 cm. What is the common charge q carried by each ball?

    2. Relevant equations
    Coloumb's law

    3. The attempt at a solution
    I've figured out that the repulsive electric force acting on one ball is 6.138e-3 N.
    This was done by figuring out the x-component of tension by using the weight.
    After that, using coloumb's law, i got that
    F = (9.99e10)(q2)
    i then figured that the net force would equal F + F.
    I added the two force vectors using the cosine law and splitting it into components and i arrive at
    q = 1.88e-7 C
    however, this seems to be wrong.

    Can anyone help please?
    Last edited: Feb 5, 2009
  2. jcsd
  3. Feb 5, 2009 #2
    I solved it!
    Could a moderator please close this thread?
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