An aluminium block has a volume of 480 cm3. What is the mass of the block if the density of aluminium is 2.7 g/cm3?


\rho=2.7 g/cm^3

v=480 cm^3

m = 480 cm3 x 2.7 g/cm3

m = 1296 g

The mass of the aluminium block is 1 296 g or 1.296 kg.

The units of density

For small volumes density is measured in g/cm3.

For larger volumes density is measured in kg/m3.

1 g/cm3 = 1 000 kg/m3
  • To convert from kg/m3 to g/cm3, divide by 1000.
  • To convert from g/cm3 to kg/m3, multiply by 1000.

Aluminium has a density of 2.7 g/cm3 = 2,700 kg/m3.

Water has a density of 1.0 g/cm3, or 1000 kg/m3.

Knowing the density of a material enables an engineer or architect to calculate the mass of a building or structure from its volume.

This in turn enables them to determine the correct depth of foundation to make the building safe.


An Olympic size swimming pool measures 50 m long, 25 m wide and has an average depth 2 m. What is the mass of water in the pool if the density of water is 1000 kg/m3?

The swimming pool is a regular shape and so the volume of water is calculated using the equation:

Volume = length x breadth x height

Volume = 50 m x 25 m x 2 m = 2500 m3

m = v \times \rho

\rho = 1000 kg/m3

v = 2500 m3

m = 2500 m3 x 1000 kg/m3

m = 2,500,000 kg

The mass of water in the swimming pool is 2,500,000 kg or 2500 tonnes.