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Superposition of Forces: Finding Magnitude and Direction

  1. Aug 22, 2012 #1
    1. The problem statement, all variables and given/known data
    Part a needs to have up to 2 significant figures.
    For part b. you need to find theta or the degrees counter clockwise from +x direction.

    2. Relevant equations
    Coulombs Law:
    F = 9(10^9) |q1q2|/r^2
    r = distance in meters of two charges

    3. The attempt at a solution
    Part A.
    F(Q on q1) = 9(10^9) N*m^2/C^2 * (2*10^-6 C)(4*10^-6 C) / (0.5m)^2
    = 0.288 N

    F(q2 on q1) = 9(10^9) N*m^2/C^2 * (2*10^-6)^2 / (0.60m)^2
    = 0.1 N

    |F| = sqroot( (0.288 N)^2 + (0.1 N)^2 ) = 0.304867 N *I know this is wrong because I tried to submit this answer and it was no go.*

    Part B.
    atan(0.1 N/0.288 N) = 19.148 degress
    180 - 19.148 = 160.852 degress
    *For this part I figured I take 180 and subtract the degrees obtained to get the degrees counter clockwise of the +x direction.
  2. jcsd
  3. Aug 22, 2012 #2
    Last edited by a moderator: May 6, 2017
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