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Homework Help: Electric Field to find Mass

  1. Jan 18, 2010 #1
    1. The problem statement, all variables and given/known data
    In a laboratory, a particle of charge -6C is held stationary because it is placed in an electric field E=(0,0,-15)N/C which suspends it against gravity. What is the mass of the particle? Give answer in kg.

    2. Relevant equations
    I THINK
    E= F/q
    F= ma


    3. The attempt at a solution
    Ok, so I haven't actually had a chance to attempt this yet because A) I don't understand the notation of E in this equation, so I don't know if it is acceptable to just use -15 for E, and B) if I even have the right equations to use, I don't know what the acceleration is. Please help
     
  2. jcsd
  3. Jan 18, 2010 #2

    rock.freak667

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    It suspends it against gravity, so what is the relationship between the electric force and the mass?
     
  4. Jan 18, 2010 #3
    I don't really get what that means about it though.
     
  5. Jan 19, 2010 #4

    rock.freak667

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    The only forces acting on the mass are its weight and the electric force. If it is being suspended, what is the resultant force on it?
     
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