1. The problem statement, all variables and given/known data A charge 2Q is placed a distance 'd' from charge 4Q. A third charge 'q' is placed 3m from charge 2Q directly on the line between charges 2Q and 4Q. Find d and q such that the force between charges 2Q and 4Q is equal to 0. 2. Relevant equations Coulomb's law: f = k(|q1q2|)/r2 k = 8.99 x 10^9 (Nm^2/c^2) 3. The attempt at a solution (k)(2Q)(q)/3 = [k(4Q)(q)]/(d - 3) (d - 3)/3 = 2 d - 3 = 6; d = 9m? k(2Q)(q)/3 + [k(4Q)(q)]/6 = k(2Q)(4Q)/9; q[(k4Q)/6 + (k4Q)/6] = k8Q2/9; q[k4Q/3] = k8Q2/9; q = (3)(2Q)/9 ? q = 2Q/3 ?