1. The problem statement, all variables and given/known data In Figure 24-60, we move a particle of charge +2e in from infinity to the x axis. How much work do we do? Distance D is 6.30 m. http://img216.imageshack.us/img216/6987/fig2460.th.gif [Broken] 2. Relevant equations U = kQq/r U=-W 3. The attempt at a solution Ok since there's two stationary charges (2e and e), I figured you could use the superpositioning principle and claculate the work done to move the 2e from infinity to the x-axis against the stationary 2e plus the work done to move it against the stationary e charge. Summing them would give the answer. U1= (k)(2e)(2e)/(2d) = 7.233E-29 J U2 = (k)(e)(2e)/d = 7.23E-29 J U(total) = 7.23E-29 + 7.23E-29 = 1.4466E-28 J U = -Work 1.4466E-28 = -Work Work = -1.4466E-28 J Is my assumption that the superpositioning principle can be used false? Thank you in advance.