1. Not finding help here? Sign up for a free 30min tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Coloumbs Law

  1. Jul 8, 2008 #1
    1. The problem statement, all variables and given/known data
    The charges and coordinates of two charged particles held fixed in an xy plane are q1 = +3.5 µC, x1 = 1.5 cm, y1 = 0.50 cm, and q2 = -4.0 µC, x2 = -2.0 cm, y2 = 1.5 cm.
    (a) Find the magnitude of the electrostatic force on q2. Done I got this part =
    94.98868N
    (b) Find the direction of this force. Got this also =
    -15.9453959° (counterclockwise from the +x axis)
    (c) At what coordinates should a third charge q3 = +5.5 µC be placed such that the net electrostatic force on particle 3 due to particles 1 and 2 is zero?
    Can't get this - saw problem solving methods for questions that are very similar in previous postings, but I can't get the math to work out

    2. Relevant equations
    Got as far as q1/x^2 = q2/(x+r)^2
    r being the distance between q1 and q2 since q3 must lie to the right of q1


    3. The attempt at a solution
    many attempts at a solution - but its been 15 years since I have done significant math and I can't get anywhere now.
     
  2. jcsd
  3. Jul 8, 2008 #2
    the equation you gave in part 2 is may not be right since q3 may not be located on the same Y value as q1. The equation would look more like:
    [tex]\frac{q_1q_3}{x^2+y^2} = \frac{q_2q_3}{(r+\sqrt{x^2+y^2})^2}[/tex] (where x is distance from q1 x-coordinate to q3 x-coordinate and y is dist from q1 y-coord to q3 x-coord)

    Now I'm not sure if this is the only way to solve this but I would start with equating the x-components of the forces aka [tex]F_{1-3x} = F_{2-3x}[/tex] and then do the same for y.
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?



Similar Discussions: Coloumbs Law
  1. Coloumbs Law Problem (Replies: 3)

  2. Coloumbs Law Problem (Replies: 3)

Loading...