Density

The density of a material is a measure of how close-packed the particles are. Gases at atmospheric pressure are much less dense than solids and liquids because the particles are more widespread.

Density of a material = mass per unit volume.

ρ = m/V
Density is measured in kg m^–3 or g cm^–3.

It is measured by dividing the mass of a specimen of the material by its volume.

Typical densities of some everyday materials in kg m^–3 are:

• air 1.2
• water 1000
• concrete 5000
• iron 9000