Question

Three charged particles form a triangle: particle 1 with charge Q1 = 84.0 nC is at xy coordinates (0, 4.60 mm), particle 2 with charge Q2 is at (0, -4.60 mm), and particle 3 with charge q = 40.0 nC is at (6.40 mm, 0). What are the x component and y component of electrostatic force on particle 3 due to the other two particles if Q2 is equal to (a),(b) 84.0 nC and (c),(d) -84.0 nC, respectively?