Density
Density in theoretical definition:
Is a physical property of substance, as each component and compound has a unique density related with it. Density is defined in a relative way as the measure of the relative "heaviness" of substances with a continuous volume.
For example: A plastic cup is less dense than a ceramic cup, and A rock is clearly more dense than a crumpled piece of paper of the same size.
Density in mathematical definition:
The formal definition of density is mass per unit volume. Usually the density is expressed in grams per mL or cc. Mathematically a "per" statement is translated as a separation. cc is a cubic centimeter and is equal to a mL Thus,
Equation
Density = Mass / Volume = g / mL
Example: The mass of a person is constant. On the other hand the person may weigh 68kg on earth, but 11.3kg on the moon (because the force of gravity on the moon is 1/6 that of the earth), and be "weightless" in space.
Picture
Reference
http://www.elmhurst.edu/~chm/vchembook/120Adensity.html
