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Homework Help: Calculating the initial charge on an object

  1. Nov 4, 2014 #1
    1. The problem statement, all variables and given/known data
    Neutral metal sphere A, of mass 0.10kg hangs from an insulating wire 2.0m long. An identical metal sphere B, with charge -q, is brought into contact with sphere A. The spheres repel and settle(a picture just imagine a right angle triangle with 2 objects A and B at the bottom.) calculate the initial charge on B.

    2. Relevant equations
    Tv = Fg
    Th = Fe
    3. The attempt at a solution
    Now, I have done the whole process but I just want to know what I am doing wrong with my calculator( we have done it in class) here was the last part of my solution: 16sin^3*12/9*10^9= q^2. OK so the answer was for this question was 4*10^-6 C = q. But everytime I input this in my calculator the answer becomes 0.000030433 or 3.04*10^-5
  2. jcsd
  3. Nov 4, 2014 #2
    Did they give you the distance between the two spheres after settling? otherwise your answer would have to be the distance as a function of initial charge
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