Surface density of a disk
= Surface density of a disk
{title2=$\Sigma$}
The surface density of a disk is its volume density integrated vertically, $\Sigma=\int_{-\infty}^{\infty}\rho\,dz$.
= Surface density of a disk
{title2=$\Sigma$}
The surface density of a disk is its volume density integrated vertically, $\Sigma=\int_{-\infty}^{\infty}\rho\,dz$.