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Homework Help: Gravitation Point Particles problem

  1. Nov 6, 2007 #1
    I am having trouble solving this problem:

    Three point particles are fixed in position in an xy plane. Two of them, particle A of mass 6.00g and particle B of mass 12.0g, are shown in Fig12-38 (the figure has A at the origin and B 30 degrees above the negative side of the x-axis) with a separation of dAB=.500m at angle 30 degrees. Particle C, with mass 8.00g, is not shown. The net gravitational force acting on particle A due to particles B and C is 2.77x10^-14N at an angle of -163.8 degrees from the positive direction of the x axis. What are (a) the x coordinate and (b) the y coordinate of particle C?

    I tried to solve a system of two equations since the problem gave us Fnet=2.77x10^.14N and the angle=-163.8 degrees:
    Fnet=(Fx^2+Fy^2)^1/2 and Tan(0)=y/x
    but i sill could not find the solution.
    Thanks for the help in advance.
  2. jcsd
  3. Nov 6, 2007 #2


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    Homework Helper

    first get the force due to B on A... then from that get the force due to C on A...

    once you have the force due to C on A... just use coordinates of C.. (x,y). what is the force of C on A in terms of x and y (set this force equal to the force you got above)... you'll get 2 equations in 2 unknowns.
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