specific weight | specific mass | specific gravity of liquid

specific weight specific mass specific gravity of liquid

Specific Mass [Density] :

Density is defined as mass per unit volume. Mass is a property.

If ρ = density (kg/m3) ,m = mass (kg), V = volume (m3)

ρ = m / V

Specific Weight :

Specific Weight is defined as weight per unit volume. Weight is a force.

If γ = specific weight (N/m3), ρ = density (kg/m3), g = acceleration of gravity (9.81 m/s2)

γ = ρ g

Specific Gravity [Relative Density] :

Specific Gravity – SG – is a dimensionless unit defined as the ratio of the density of a substance to the density of water – at a specified temperature.

If SG = Specific Gravity of the substance ,ρsubstance = density of the fluid or substance (kg/m3), ρH2O = density of water – normally at temperature 4 oC (kg/m3)

[It is common to use the density of water at 4 oC as a reference since water at this point has its highest density of 1000 kg/m3.]

SG = ρsubstance / ρH2O