Viscous drag coefficient
= Viscous drag coefficient
{title2=$\mathbf F_{\rm drag}=-\gamma\mathbf v$}
The proportionality between drag <force> and relative <velocity> in a linear low-speed regime. Its translational units are $\mathrm{kg\,s^{-1}}$; thermal equilibrium gives the <Einstein diffusion relation> $D=k_BT/\gamma$.