1. The problem statement, all variables and given/known data Two charges Q1 and Q2 of equal magnitude but opposite signs are fixed a distance 5.00 m apart in a vacuum The line PQ is a 12.0 cm section of the line joining the two charges and is placed centrally between them. Over the distance PQ the electric field may be taken to be uniform. An electron is released, with negligible initial speed, from point P at time t = 0. At t = 1.00 × 10−2 s the electron is observed to pass point Q. Determine the magnitude and sign of both Q1 and Q2 2. Relevant equations Fel = 1/ 4 pi E q1q2 / r^2 a = 2s / t^2 3. The attempt at a solution well basically I think I need another equation to combine with coulomb's law so I can make Q the subject and thus find the magnitude of charge. I know that Fel is inversely proportional to r^2 and that if I find Q I just need to halve the value as both charges are equal. as for the last part of the question electron = - so Q2 = + and thus Q1 = - obviously there is something I am missing here a helpful pointer please?