Having some trouble with an electric potential problem. I thought I understood it but I keep getting an infinity in the equation which just can't happen. Three small spheres with charge 2.00 mC are arranged in a line, with sphere 2 in the middle. Adjacent spheres are initially 8.00 cm apart. The spheres have masses m1 = 20g, m2 = 85.0g and m3 = 20.0g, and their radii are much smaller than their separation. The three spheres are released from rest. So from the last sentence I get the idea to treat it as 3 point charges. For point charges potential = kq/r. For the first question I need to find the acceleration on point 1. My idea was to add up both forces applied to it by points 2 and 3. I used: F = k*2.00mC/.08 + k*2.00mC/.16 F = ma so a = F/m But that gives me a = 168596338021 m/s^2 which doesn't work and seems rather large. For the next 3 parts it wants me to find the velocity of each particle when they're far apart. The middle one is easy since its 0. The outter 2 will be equal but I can't seem to solve it without an infinity. I know I will need to use K_1 + U_1 = K_2 + U_2. I am not sure how to approach it since U = -QV, and V = the integral of k*q/r from r_0 to far away, aka infinity. Secondly, when U = -qV, what value to I use for Q and q?? Am I approaching this part wrong? Thanks for the help.