Relative density
Tanusri Gururaj, Academic content writer of Physics at Edumarz
The density of a substance = mass/volume
Unit of density = kg m-3
Density is the characteristic property of a substance as, under specified conditions, it remains the same.
The relative density of a substance is the ratio of the density of that substance to the density of water.
Relative density of a given substance = density of substance/density of water
The relative density is a ratio of two densities and, hence, it is unitless.