1. The problem statement, all variables and given/known data In the figure, what is the force on charge Q3? Q1 = 5×10-6C, Q2 = -3×10-6C, Q3 = 4×10-6C http://www.usi.edu/science/physics/pickett/206/4p2f1.jpg [Broken] 2. Relevant equations Coulomb's law 3. The attempt at a solution I thought I could just find the charges on q1 and 3 and then on 2 and 3 and add them but I don't think that is right. Can you just add electrical forces?