1. The problem statement, all variables and given/known data The 2.1mm diameter spheres in the figure are released from rest. What are their speeds vc and vd at the instant they collide? Spheres: C has 2nC of charge and a mass of 1g. D has -1nC of charge and a mass of 2g. The starting distance between the two spheres is 10mm. Each sphere as a diameter of 2.1mm. 2. Relevant equations V=(1/4pi*ε_0)*Q/r Q is the charge and r is the distance between the two spheres. K=.5*mv^2 3. The attempt at a solution ΔKC+ΔUC = 0 = ΔKD+ΔUD Ki for spheres C and D are 0 since the spheres begin at rest: KCf+UCf-UCi=KDf+UDf-UDi The rest of my attempt is basically putting the numbers in and solving for KCf in terms of KDf and then using that to get KDf. I just want to know if I am heading in the right direction.