Superpositions of electrostatic forces

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Homework Statement



Three particles P1, P2, and P3 are located at the points (−2.00, −1.00), (0, 2.00), and (3.00, −1.00), respectively. P1 has a charge of 5.00 μC, but the charges of P2 and P3 are unknown. However, the three particles exert no net force on a charged particle that is placed at the origin. You are asked to find the unknown charges. (a) Use the fact that the net horizontal force on the particle at the origin is zero to find the unknown charge on P3. (b) Then use the fact that the net vertical force on the particle at the origin is zero to find the unknown charge on P2.

Homework Equations



Fnet = (Kq1q2)r2

K = 9*109

The Attempt at a Solution



I am at a loss on where to go with this one. I have tried about 10 different things but keep getting stuck with unsolved variables.

I also attached a drawing i did with some numbers for angles and such that i came up with.

Any help would be greatly appreciated!
 
Attachments
  • Hand-drawn diagram of a horizontal and vertical axis crossing at the origin, with a dot at the origin and dots on the vertical axis above and along two lines to lower left and lower right, with angles labeled 26.7 degrees, 18.43 degrees and 108.43 degrees.
    phys.png
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From the given hint you can write
K*Q*Q1*cosθ1/(d1)^2 =k*Q* Q3*cosθ3/(d3)^2. where q is the charge at the center.You have already found θ1 and θ3. So find Q3.
Similarly
kQ*Q2/(d2)^2 =K*Q*Q1*sinθ1/(d1)^2 + k*Q* Q3*sinθ3/(d3)^2. Find Q2.
 
This is one of the methods I used and I kept coming up with 9*10-6 which is wrong so, I don't know what to do. Maybe my math is wrong.

([STRIKE]K[/STRIKE] (5*10-6) [STRIKE]Q0[/STRIKE] cos (26.56)) / (2.23)2 = ([STRIKE]K [/STRIKE]Q3 [STRIKE]Q0[/STRIKE] cos(18.43)) / (3.16)2