1. The problem statement, all variables and given/known data Two small beads having positive charges 3q and q are fixed at the opposite ends of a horizontal, insulating rod, extending from the origin to the point x = d. A third small bead (in the middle) is free to slide on the rod. At what position is the third bead in equilibrium? Can it be stable in equilibrium? 2. Relevant equations Coulomb's Law F = ke (q1q2)/r^2 3. The attempt at a solution I'm not sure how to go about this problem because I don't know the charge of the third bead.