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Homework Help: Net Force of a charged particle (Coulomb's Law)

  1. Feb 1, 2008 #1
    1. The problem statement, all variables and given/known data
    I really can't see where I am going wrong here. I would latex out my work, but it would take way too long, so I have scanned it in. It should be easy enough to read though.

    Its NUMBER 7, fig 21-22 Also the blurr says '100 nC'

    3. The attempt at a solution
  2. jcsd
  3. Feb 1, 2008 #2
    Last edited: Feb 1, 2008
  4. Feb 2, 2008 #3
    .The solution says .17 N and -.046 N but clearly mine arent even close. I have redone the problem twice and keep getting the same components
  5. Feb 2, 2008 #4
    This is killing me! This should be simple vector addition, nothing more. I'm going to go smash something. . .
  6. Feb 2, 2008 #5
    Well, I think the you got the -.046 thing correct, and the other answer looks to be .67... so i think its a typo error.

    Neways, what did you smash?:wink:
  7. Feb 2, 2008 #6


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    Why did you put 0.025 in your denominator? I don't understand why you have it as 0.5a^2. a = 0.05 m. So that is the distance between Q3 and Q4 and Q3 and Q1.

    I got the same answers as the book did.
    Last edited: Feb 2, 2008
  8. Feb 2, 2008 #7
    I am such a douchebag sometimes. Ya know. I see the variable r and I automatically this radius of circle and I cut it in half. Thanks hage.
  9. Feb 2, 2008 #8


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    lol, it happens. You're welcome.
  10. Feb 2, 2008 #9


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    I looks like you are making some silly mistakes. E.g. i) (5cm)^2=(0.05m)^2=0.0025m^2. Why are you using (0.025m)^2? ii) In F31 you have the charges as 100 and 100, shouldn't they be 100 and 200? Yeah, stuff like that does make me want to hit something. Usually myself. Don't do it.
  11. Feb 2, 2008 #10
    :puts giant rubber mallet down: oh. . . okay :(
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