This is probably child's play for most of you, but a guy like me struggles to understand basic concepts. A kick in the pants to set me off in the right direction would be greatly appreciated. 1. The problem statement, all variables and given/known data How far must the point charges q_1 = 7.60 microCoulombs and q_2 = -24.0 microCoulombs be separated for the electric potential energy of the system to be -110 J? 2. Relevant equations E=F/q F=k(q1*q2)/(r^2) k=8.988810^9 (Nm^2)/(C^2) Volt = N/C W=Fr r= distance in this case 3. The attempt at a solution Honestly, I'm not quite sure where to start. Not sure which formula I'm supposed to use. I gave it a try anyway, though. Coulomb's Law seems perfectly reasonable until I realize that I don't have a value for distance. All the same, I multiplied 8.988E9 by 7.6E-6 and 24E-6 and assumed my force would equal 1.63941r^2 N. Then, since work is measured in joules and so is potential energy, I tried to use the formula W=Force x distance (and I still don't know the distance), giving me something like 1.63941r^3 Joules. And if I wasn't already lost, I notice that electric potential is supposed to be measured in volts. But since the question doesn't ask for volts, all that's left is for me to solve for r. I try to solve for r by means of 1.63941r3=110, which gives me 4.06 (4.1) meters. Since the question wants the answer in cm, I used 4.1x10^2 cm. Obviously, I got the answer wrong. It's no surprise, seeing as how I'm just sort of drowning in a vast ocean of numbers. Can I get a metaphorical life preserver?