Question

Two positive charges q1 = q2 = 2.0 μC are located at x = 0, y = 0.30 m and x = 0, y = -0.30 m, respectively. Third point charge Q = 4.0 μC is located at x = 0.40 m, y = 0.What is the net force ((a)magnitude and (b)direction) on charge q1 exerted by the other two charges?

Answer 1

Use F = K q q' / r^2 for both the Q q1 and q1 q2 combinations, then add these forces by adding components of the vectors.