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Homework Help: I don't know where went wrong help needed!

  1. Jan 28, 2009 #1
    1. Two parallel conducting plates that are in deep space are brought to a potential difference of 4.50E+3 V, and a small pellet of mass 5.70 mg carrying a charge of 7.75*10^-7C accelerates from rest from the positive plate. With what speed will it reach the other plate?

    It seemed pretty obvious for me that by multiplying the potential difference and the charge on the pellet, the work done on the charge will be calculated. This work is equivalent to the kinetic energy of the pellet,
    So change in U = 4.5*10^3 V * 7.75*10^-7 C = 3.4875*10^-3 J
    and change in U = Kinetic energy = 0.5*(0.0057g)*v^2
    solving for V I got v= 1.106 m/s
    but the answer is wrong... can someone give me a hint??????
  2. jcsd
  3. Jan 28, 2009 #2
    Kilogram is the SI standard mass unit to use with Joules. Convert the mass accordingly.
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