Three point charges are located at the corners of an equilateral triangle as shown in Figure P15.13 (q = 3.00 µC, L = 0.400 m). Calculate the net electric force on the 7.00 µC charge.
° (counterclockwise from the +x axis)
The Attempt at a Solution
F_12 = 8.9875 x 10^9 (3e-6)(7e-6)/.4e2 = 1.18 N
F_13 = 8.9875e9 (7e-6)(4e-6)/.4e2 = 1.57 N
F_12x = 1.18cos60 = .59 N
F_12y = 1.18sin60 = 1.0219 N
F_13x = 1.57cos60 = .785 N
F_12y = -1.57sin60 = -1.3697 N
then i added them up
Fx = .59 + .785 = 1.375 N
Fy = -1.3597 + 1.0219 = - .3378 N
I know that to get the degree its arctan Fy/Fx but i get the incorrect answer. Is there something wrong in the equation or im i using the wrong number?
I understand how to do the first part which is 1.4 N of electric force on 7uC charge.
Thanks for any help.