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file=problems/prob_1_3.eps,height=2.5in

Two positively charged pith balls of mass $m$ each have a charge $Q$ and are suspended by insulating (massless) lines of length $L$ from a common point as shown. Assume that $L$ is long enough that $\theta$ at the top is a small angle. Find $\theta$ such that the pith balls are in static equilibrium in terms of $k$, $Q$, $m$, $L$ and of course $g$.