Question

(a) Define density. What is the SI unit of density?
(b) Define relative density. What is the SI unit of relative density?
(c) The density of turpentine is 840 kg/m³. What will be its relative density? (Density of water = 1000 kg/m³)

Answer 1

(a) Density is defined as the mass per unit volume of a substance. The symbol for density is ρ. Mathematically, density is defined as
$\mathrm{\rho }=\frac{m}{V}$
The SI unit of density is kg/m³.

(b) Relative density of a substance is the ratio of density of the substance to the density of water. Relative density has no unit.

(c)
$$\begin{gathered} \mathrm{Relative}\mathrm{density}=\frac{\mathrm{Density}\mathrm{of}\mathrm{turpentine}}{\mathrm{Density}\mathrm{of}\mathrm{water}} \\ =\frac{840\mathrm{kg}/{\mathrm{m}}^3}{1,000\mathrm{kg}/{\mathrm{m}}^3} \\ =0.84 \end{gathered}$$

Ans: Relative density of turpentine = 0.84.