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Homework Help: Force between Protons

  1. Feb 1, 2009 #1

    There are 3 Protons (P) that form a triangle.
    distance PA-PB -->15mm
    distance PB-PC -->20mm
    distance PA-PC --> unknown

    I have to calculate the last distance and the forces between the protons by using coulomb´s laws.

    I tried to calculate the force between AB and BC:
    F1=1.02 E -24
    F2=5.76 E -25

    Now I don´t know what to do next? Can I use the a²+b²=c² for either the Fore or the distance?

  2. jcsd
  3. Feb 1, 2009 #2


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    You've got a triangle with 2 known sides 15 and 20. The third side could be anywhere from 0 to 35 mm and still form a triangle. Do we have any more information to help us decide what the 3rd side is? Something about the forces, perhaps?
  4. Feb 1, 2009 #3
    The teache or the problem didn´t say it but on the picture that I got it looks like there is a right angle, where Proton B is.
  5. Feb 2, 2009 #4


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    Well, that makes it easy. Just a geometry question, no physics involved.
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