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Homework Help: Electric force between objects that are in brief contact

  1. Mar 25, 2013 #1
    1. The problem statement, all variables and given/known data

    Two small charged objects of the same mass and volume are brought into brief contact with each other. If the initial charges on the two objects are -3.00 x10^-6 and -1.50 x10^-6, what is the electric force between the objects when they are seperated to a distance of 0.500m after contact?

    The answer is 1.82 x10^1 N

    2. Relevant equations


    3. The attempt at a solution

    I thought it is just plug in the numbers but i get a different answer. So is there anything that goes on when they are in contact?

    F= (9.0x10^9)(-3.00x10^-6)(-1.50x10^-6)/(0.500)^2
  2. jcsd
  3. Mar 25, 2013 #2
    The important thing here is that they are brought into contact first.
    What changes does that cause?
  4. Mar 25, 2013 #3
    im not really sure...

    umm their initial distance? Or it will have to be something to do with their charge (transfer of electro maybe)?
  5. Mar 25, 2013 #4
    I think the objects you have are conductors?? What happens in this case?? And anyway are you sure the result is not 1.82x10^(-1)?? (you put 10^1)...
  6. Mar 25, 2013 #5
    I think you have to assume they're conductors, since it gives the right answer :)

    Yes - this is the answer I got.

    Jabababa - When you put two unequally charged conductors in contact, what happens to the charges on them?
  7. Mar 25, 2013 #6
    Just as I thought :smile:
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