Definition:Mass Density

From ProofWiki
Jump to navigation Jump to search

This page is about Mass Density. For other uses, see Density.


Mass density is a physical quantity.

The mass density of a body is its mass per unit volume.

For a homogeneous body it is found by finding its total mass and dividing it by its total volume:

$\rho = \dfrac m V$


$m$ is the body's mass
$V$ is the body's volume

However, if the substance of the body varies throughout, then its mass density may be a function of position within the body.


The usual symbol used to denote (mass) density of a body is $\rho$ (Greek letter rho).

Some sources use $d$, but that has so many other uses that it may become confused with other things.


The dimension of (mass) density is $\mathsf {M L}^{-3}$: mass per unit volume.


Area Mass Density

The area mass density of a two-dimensional body is its mass per unit area.

Linear Mass Density

The linear mass density of a one-dimensional body is its mass per unit length.

Also known as

Mass density is usually known just as density, but there are multiple usages for that term.

If it is necessary to distinguish between mass density, area mass density and linear mass density, the term volumetric mass density can be used.

$\mathsf{Pr} \infty \mathsf{fWiki}$ will generally use the unadorned term density in its exposition unless there is cause for confusion.

Also see

  • Results about mass density can be found here.