1 \begin{problem*}{23.17}
2 A point charge $+2Q$ is at the origin and a point charge $-Q$ is
3 located along the $x$ axis at $x=d$ as in Figure P23.17. Find a
4 symbolic expression for the net force on a third point charge $+Q$
5 located along the $y$ axis at $y=d$.
9 Summing the forces from the other two charges
11 \vect{F} = \vect{F}_0 + \vect{F}_x
12 = k\frac{Q\cdot2Q}{d^2}\jhat
13 + k\frac{Q\cdot(-Q)}{d^2+d^2}\frac{-\ihat+\jhat}{\sqrt{2}}
14 = k\frac{Q^2}{d^2}\p({ 2\jhat - \frac{1}{2\sqrt{2}}(-\ihat+\jhat) })
15 = \ans{k\frac{Q^2}{d^2}\p[{ \frac{\ihat}{2\sqrt{2}}
16 + \p({2-\frac{1}{2\sqrt{2}}})\jhat }] }