Question

(a) Define density. What is the SI unit of density?
(b) Define relative density. What s the SI unit of relative density?

Answer 1

(a) The density of a body is defined as the mass per unit volume of the body. $\mathrm{Density}=\frac{\mathrm{Mass}\mathrm{of}\mathrm{the}\mathrm{body}}{\mathrm{Volume}\mathrm{of}\mathrm{the}\mathrm{body}}$

The SI unit of the density is kg/m³

(b) The density of a body relative to the density of the water is known as the relative density of the body. It is basically the ratio of the density of a body to the density of water.

$\mathrm{Relative}\mathrm{density}=\frac{\mathrm{Density}\mathrm{of}\mathrm{the}\mathrm{body}}{\mathrm{Density}\mathrm{of}\mathrm{the}\mathrm{Water}}$

Relative density is a unitless quantity, as it is given by the ratio of densities.