1. The problem statement, all variables and given/known data A charge of 2.21E-9 C is placed at the origin, and a charge of 3.78E-9 C is placed at x = 1.60 m. Find the position at which a third charge of 2.94E-9 C can be placed so that the net electrostatic force on it is zero. 2. Relevant equations Coloumb's law 3. The attempt at a solution All 3 charges are positive, so for the net force to be zero, I believe that the 3rd charge will go in the middle of the other 2 charges. +q1 |----1.60m - r -----| +q3 |------ r------| +q2 Knowns: q1 = 2.21 x 10^-9 C q2 = 3.78 x 10^-9 C q3 = 2.94 x 10^-9 C r (between q1 and q2) = 1.60 m F1 = F2 the k and q3 both cancel, leaving me with: q1 / (1.60m - r)^2 = q2 / r^2 I cross multiplied, giving me: q1 / q2 = (1.60m - r)^2 / r^2 This is where I think I'm having a problem. From this point, I found 2 different answers, and both turned out to be wrong: 0.91m and 1.05m (both from q1). Can anyone please help?