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Homework Help: Electric Forces in a Triangle (math check?)

  1. Feb 11, 2012 #1
    Hi Guys I've tried to do this problem but the answers are not being accepted is the math wrong? or did i forget a concept? Thanks for taking a look

    The triangle is set by Q1 on the top of the triangle Q2 on the bottom left and Q3 on the bottom right

    Calculate the magnitude of the net force on each due to the other two. Three charged particles are placed at the corners of an equilateral triangle of side 1.20 (see the figure ). The charges are Q1= 7.0 , Q2= -8.6 , and Q3= -5.4 .

    F(e)= k (Q1*Q2)/ r^2

    F(12) =(8.98e9*7e-6*8.6e-6)/ (1.2)^2 F(23) = 8.98e9*8.6e-6*5.4e-6/ (1.2)^2

    F(31) =(8.98e9*5.4e-6*7e-6) / (1.2)^2

    F(12) = .3754N
    F(23) = .2896N
    F(31) = .2357N

    Fx1 = -Cos(60)(.3754)+Cos(60)(.2357)= -.069
    Fy1 = -Sin (60) (.3754)-Sin(60)(.2357)=-.121

    F1= sqrt((-.069)^2+(-.121)^2)= .139

    Fx2 = -Cos(60)(.3754)-.2896=-.1025
    Fy2 = Sin(60)(.3754)=.3247

    F2= sqrt((-.1025)^2+(.3247))=.340

    Fx3 = Cos(60)(.2357)+.2896=.4075
    Fy3 = Sin(60) (.2357)=.204

    F3= sqrt((.4075)^2+(.204)^2)=.226
    1. The problem statement, all variables and given/known data

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    3. The attempt at a solution
  2. jcsd
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