Linear drag
= Linear drag
{title2=$\mathbf F_d=-\alpha\mathbf v$}
Linear drag opposes the <velocity> relative to the surrounding medium with magnitude proportional to its <speed>, where $\alpha>0$. Its <power> is $\mathbf F_d\cdot\mathbf v=-\alpha|\mathbf v|^2$, so it dissipates <kinetic energy>. Under a constant external <force>, the resulting <linear ordinary differential equation> relaxes exponentially on the <time> scale $m/\alpha$.