Keplerian Disk

A disk of material that obey’s Kepler’s laws of motion due to the dominance of a massive body at its centre.

The velocity, v of the material a distance, R from a central star/black hole is proportional to R^-1/2.

Newton’s laws of gravity and motion demonstrate that the velocity v obeys:

$v = \sqrt{GM\over{R}}$

where G is Newton’s gravitational constant, and M is the mass of the object the disk is orbiting.