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Homework Help: Finding net force on object with more than one force

  1. Mar 4, 2009 #1
    1. The problem statement, all variables and given/known data

    Three 8kg spheres are located at (0, 1.7), (1.7, 1.7), and (1.7, 0) named A, B, and C respectively. What is the net gravitational force acting on sphere A?

    2. Relevant equations

    F = GMm/r2

    3. The attempt at a solution

    So far I've tried this several ways with no success. I'm not really sure where to begin. Since there is only one acting in the vertical direction I started there. I found the amount of force that the two had towards each other. Then I did some math to determine how much of that is downward. I came up with 3.1388e-10 which is incorrect. I tried the other one in a similar fashion. I found both of the forces then added the two together. Not directly but finding how much is being pulled horizontally and adding to the other. I'm almost 100% sure that I am forgetting something or just messed up somewhere along the way.
  2. jcsd
  3. Mar 4, 2009 #2


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    Homework Helper

    They are vectors aren't they?

    G1 = ... i + ... j

    G2 = ... i + ... j

    G1 + G2 = ... ?
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