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Homework Help: Electric potential

  1. Jan 23, 2007 #1
    1. The problem statement, all variables and given/known data

    Two pont charges of magnitude 6.17 nC and -4.32 nC are separated by 29.1 cm. The acceleration of gravity is 9.8 m/s^2. the Coulomb constant is 8.98755 x 10 ^9 N m^2/C^2. What is the electric potential at a point midway between the charges? Answer in units of V.

    2. Relevant equations

    well I know Columb's law obviously comes into effet. If its just finding the electric force of repulsion between the 2 object it would be ez. But the potential? IS the acceleration of gravity even relevant in this problem?

    3. The attempt at a solution

    I know that (electric potential ) V = kq/ r and Columb's equation is F = Kq1q2/r^2. How can I manipulate both of these equations?

  2. jcsd
  3. Jan 23, 2007 #2
    I dont know why they threw in gravity, just add up the voltages. Coulombs law does not need to be manipulated
  4. Jan 23, 2007 #3
    So do I just use V = Kq/r and solve for 6.17 and -4.32 making sure that I keep the signs? and then add these up? The question asked for the midway between charges how does this come into effect? is my r value 1/2 of 29.1 cm?

    Let me know
  5. Jan 23, 2007 #4
    Yes, but positive/negative orientation of distance doeesnt matter. The distance is positive for both voltages. Needless to say, youll wind up with a positive answer
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