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Homework Help: Help with Electric charges using coulomb's law

  1. Oct 2, 2012 #1
    1. The problem statement, all variables and given/known data

    Two point charges are located on the y axis as follows: charge q1=-2.5nC at y=-0.6m, and charge q2=+3.5nC at the origin. What is the net force (x, y components) exerted by these two charges on a third charge q3=+5.0nC located at y=-0.4m?

    2. Relevant equations
    F=k (abs(q1*q2)/r^2)
    k is constant k=9x10^9 N*M^2/C^2

    3. The attempt at a solution
    Like Charges repel, opposite charges attract.
    q2 is at the origin, q1 is -0.6m far from q2. q3 -0.4m far from q2.
    Not sure if i quite got it right...
    if any1 can help me out...thx a lot for your time.
  2. jcsd
  3. Oct 2, 2012 #2
    im pretty sure you would do Fnet = F1 + F2

    where F1 is the distance from the third charge to one charge

    F2 is the distance from the third charge to the second point charge

    oh and the equation you gave is the magnitude
    remove the absolute value and treat each force as a vector
  4. Oct 2, 2012 #3
    so what is gne be net force using the coulombs law...
    Fq2 to 3 =(9*10^9)(3.5nC)(5.0nC)/-0.4^2
    Fq1 to 3 = (9*10^9)( -2.5nC)(5.0nC)/-0.6^2
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