Density

The mass density or density of a material is defined as its mass per unit volume. The symbol most often used for density is $\rho$. Mathematically, density is defined as mass divided by volume: $\rho = m/V$, where $\rho$ is the density, $m$ is the mass, and $V$ is the volume. In some cases, density is also defined as its weight per unit volume, although this quantity is more properly called specific weight.