# Oscillations of a tetra-atomic molecule

Consider the following model of a tetra-atomic molecule: Four point-charges with charge $$q$$ and mass $$m$$ are connected by light rigid rods of length $$l$$. Clearly, the molecule is in equilibrium when the charges form a square of side $$l$$. Since this equilibrium is stable, the molecule can oscillate as shown in the figure. If the parameters $$q$$, $$m$$, and $$l$$ satisfy $\frac{k q^{2}}{m l^{3}}=10^{4}~\mbox{s}^{-2} \quad \textrm{where} \quad k=\frac{1}{4\pi \epsilon_{0}},$ find the period $$T$$ in seconds of small oscillations.

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