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Homework Help: Graphical Analysis for Force of Electrostatic Replusion vs Produc of Charge help

  1. Feb 29, 2012 #1
    1. The problem statement, all variables and given/known data

    What does the slope represent for a graph of force of electrostatic (y-axis) as a function of product of charge (x-axis)?

    -charges are not given - the experiment was done by charging 1 sphere, touching it with sphere two so that each sphere is 1/2 q. By touching sphere 1 with sphere 3, sphere 1 gets a charge of 1/4 while sphere 2 still has a charge of 1/2 (how charge was manipulated). These "coefficients" were graphed on the x-axis.
    my slope equals 8.57 x 10^-4 N/q^2, not sure what it represents

    2. Relevant equations

    Fe=kq^2 / r^2

    3. The attempt at a solution
    I set up the equation as:

    Fe = 8.57 x 10^-4 N/q^2 q1q2 = kq1q2/r^2
    =8.57 x 10^-4 N/q^2=k/r^2
    not sure how to end or if this is the right track at all.

    any suggestions/answers?
  2. jcsd
  3. Mar 1, 2012 #2


    User Avatar
    Homework Helper

    Welcome to PF!
    It looks like you graphed F vs q² and you are comparing with F = kq²/R².
    R should have been kept constant as q² was varied.
    If so, the formula F = kq²/R² becomes F = constant*q².
    This is like y = mx in math, since you have q² on the x axis.
    So you should expect a straight line graph whose slope = m = k/R².
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