Using the relationship between density, mass and volume to solve for the Star's mass Density is the amount of matter in a given volume.
Density is a characteristic property of matter.
This means that density can be used to identify a sample of matter and the size of your sample will not change your result. Density is determined by dividing the mass of a substance by the volume occupied by that mass. If you know the volume and density of an object, a simple rearrangement of the above equation wil let you calculate it's mass. Click here to start by finding the volume of Cyg X-1. Show me a printable version of this page.