[SOLVED] Work Needed to Move a Charge 1. The problem statement, all variables and given/known data Three identical point charges Q1, Q2, and Q3 all having charge 3 microCoulombs are located at the vertices of an equilateral triangle with sides s=3 m. How much work would I have to do to move Q1 to a point on the line connecting Q2 and !3 (which are fixed) if this point is a distance .4 s from Q2 and a distance .6 s from Q3? http://img129.imageshack.us/img129/1091/trianglejp1.th.gif [Broken] (Picture obviously not drawn to scale) 2. Relevant equations W = Fd = qEd E = kQ/d 3. The attempt at a solution I am using q = 3*10^-6 Coulombs in all of my attempts. The thing that is throwing me off is what to use as the distance and electric field. I did two different approaches: Attempt 1 First I tried to find the distance between Q1 and its destination point. I just made a right triangle: http://img98.imageshack.us/img98/1240/88380904mi7.gif [Broken] And the hypotenuse was sqrt(2.34). Then, E = kq/d E = (9*10^9)(3*10^-6)/sqrt(2.34) E = 17650.45216 N/C So I plugged in E to the formula for Work W = qEd W = (3*10^-6)(17650.45216)(sqrt(2.34)) W = .081 J Attempt 2 I tried to calculate the electric field at the point Q1 between Q2 and Q3. For distance i used 1.2 (.4*3m) and 1.8 (.6*3m). First, E_tot = E1 + E2 E=kq/d^2 (electric field at a point between two charges) E1=(9*10^9)(3*10^-6)/1.2^2 E1=18750 E2=(9*10^9)(3*10^-6)/1.8^2 E2=-8333.34 (rounded up, because it was .3 repeating, negative because the direction of the field that acting on Q1 is to the left) E_tot = E1+E2 E_tot = 18750 - 8333.34 = 10416.67 Then, W = qEd d will remain the same as in attempt 1. W = (3*10^-6)(10416.67)(sqrt(2.34)) W = .0478 J --- There you have it. Neither of them were the right answer. Please help. I know I am close but like I said, I am confused as what to use for E and d. Thank you.