1. The problem statement, all variables and given/known data Three spheres, each with a negative charge of 4.0 X 10^6 C, are fixed at the vertices of an equilateral triangle whose sides are 0.20 m long. Calculate the magnitude and direction of the net force on each sphere. 2. Relevant equations Fe = kq1q2 / r^2 3. The attempt at a solution I used vector components to try to solve this question. I think that we only have to find the net force on one of the spheres since the radius and the charges are same throughout the system. Sphere 1 is the "main" sphere from which I want to find out the net force. Force of Sphere 2 on 1: F2 = kq1q2 / r^2 = (9 X 10^9)(4.0 X 10^-6)^2 / (0.2)^2 = 3.6 N For the x-component of force of sphere 2 on 1: F2x = 3.6 X sin 30° = 1.8 N For the y-component of force of sphere 2 on 1: F2y = 3.6 X cos30° = 3.12 N The force that was exerted by sphere 3 on 1 is the same force as 3.6 N since all the values are the same. Only the direction is different. Here is the vector sum: x = -3.6 - 1.8 = -5.4 y = 3.12 c^2 = 3.12 ^2 + (-5.4)^2 = 6.2365 = 6.2 N Therefore, the net force is 6.2 N. BUT..... how do I get the angle Θ, because in the book it says 150° away from each side. Please anyone help. It's just a little problem. Thanks.