Radial impulse
= Radial impulse
{title2=$\Delta\mathbf p\parallel\mathbf r$}
An <impulse> directed along the position vector relative to a specified origin. Its <angular impulse> vanishes because $\Delta\mathbf J=\mathbf r\times\Delta\mathbf p=0$. It can nevertheless change <kinetic energy>; if an initially circular <Kepler orbit> receives radial <velocity> $w$, the added specific <orbital energy> is $w^2/2$.