= Endpoint collision of two freely rotating equal rods
{title2=$J=\frac{mV(1+e)}2,\quad |\omega|=\frac{V(1+e)}{4\ell}$}
Each massless rod has endpoint masses $m$ at distance $\ell$ from its centre, hence total mass $2m$ and <moment of inertia> $2m\ell^2$. In a symmetric opposite-end collision with centres approaching at speed $V$, a horizontal <impulse> $J$ changes each centre speed by $J/(2m)$ and each contact-point speed by $J/m$. The <coefficient of restitution> gives $2J/m-2V=2eV$. Both rods rotate in the same sense for the staggered vertical configuration; their centre speeds after impact are $V(3-e)/4$.
// Target: electromagnetism.bigb
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