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Homework Help: Electric Charges, Electric Forces and Electric Fields

  1. Apr 11, 2010 #1
    1. The problem statement, all variables and given/known data

    An object with a net charge of 24 x 10^-6 Coulombs is placed in a uniform electric field of 610 N/C, directed vertically. What is the mass of this object if it floats in this electric field?

    2. Relevant equations

    Felectric = kC (q*q/r^2)
    Electric Field= kC (q/r^2)
    E= Felectric/q
    F=ma

    3. The attempt at a solution

    I know I need to use F=ma, but I do not know the acceleration. I don't know how to solve this
     
  2. jcsd
  3. Apr 11, 2010 #2
    Which formula can be used to find the strength of the electric force due to the field?
     
  4. Apr 11, 2010 #3
    Electric field = Electric force/ q (charge of object)
     
  5. Apr 11, 2010 #4
    (Electric field equals the electric force divided by the charge of the object)
     
  6. Apr 11, 2010 #5
    Once the electric force is calculated, it must be equal to the gravitational force since the charge is floating. What formula is used to calculate the gravitational force acting on a mass?
     
  7. Apr 11, 2010 #6
    F= mg
     
  8. Apr 11, 2010 #7
    Force of gravity = mass x 9.8
     
  9. Apr 11, 2010 #8
    Bingo
     
  10. Apr 11, 2010 #9
    Wow thanks! haha I may have some more questions soon too :)
     
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