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Homework Help: About coulomb's law

  1. Aug 4, 2004 #1
    Dear all...

    i have a question about coulomb's law as follows:

    if there are three point charges are placed at the x-axis, first is +C, second is -C and the last one also is -C.

    How could i know the direction of the force at the second and third one ??

    best regards.

  2. jcsd
  3. Aug 4, 2004 #2

    Doc Al

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    Staff: Mentor

    You'll have to be more specific: where are the charges? I assume you need to find the forces that these charges exert on each other? Remember that like charges (same sign) repel and unlike charges attract.
  4. Aug 4, 2004 #3
    Dear Doc Al

    what is meaning of repel ??

    if there is two postive charge at the X axis, one is 5C at x = 0, other is 6C at x = 40,
    so what is the force direction ?? positve or negative ??


  5. Aug 4, 2004 #4

    Doc Al

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    Staff: Mentor

    Repel means push away. Attract means pull together.
    I assume you are talking about the forces they exert on each other?
    Since these charges are both positive, they will repel each other. So:
    (1) the force on the 5C charge at x = 0 will point in the negative x direction
    (2) the force on the 6C charge at x = 40 will point in the positive x direction

    Make sense?
  6. Aug 4, 2004 #5
    thanks a lot !!
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