Definition:Mass Density/Area

Definition

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

Symbol

The usual symbol used to denote area mass density is $\rho_A$ (Greek letter rho).

However, some sources simply use $\rho$ if the context makes it clear that it refers to area mass density rather than volume mass density.

Occasionally, $\sigma$ (Greek letter sigma) is also used, but this is more commonly used for surface charge density.

Dimension

The dimension of area mass density is $\mathsf M \mathsf L^{-2}$: mass per unit area.

Units

• The SI units of area mass density are $\mathrm {kg} \ \mathrm m^{-2}$ (kilograms per square metre).

• The CGS units of area mass density are $\mathrm g \ \mathrm{cm}^{-2}$ (grams per square centimetre).

Thus:

$1 \ \mathrm g \ \mathrm{cm}^{-2} = 10 \ \mathrm{kg} \ \mathrm m^{-2}$

Also known as

Area mass density is usually referred to just as area density when it is clear that mass density is the kind of density under discussion.

Area (mass) density is also known as surface density, areal density or planar density.

Also see

• Definition:Mass Density
• Definition:Linear Mass Density

• Results about area mass density can be found here.