The document defines density as mass per unit volume and provides examples of the densities of fresh water and salt water. It then defines specific gravity or relative density as the ratio of the weight of a substance to the weight of an equal volume of fresh water. Specific gravity is calculated by dividing the density of a substance by the density of fresh water, which is 1000 kg per cubic meter.

1. Chapter 3
Density And Specific Gravity

2. Density is defined as ‘mass per unit volume’.
For example, the mass density of
Fresh Water = 1000 kg per cubic metre or 1.000 tonne/m3
Salt Water = 1025 kg per cubic metre or 1.025 tonne/m3
The specific gravity (SG) or relative density of a substance is defined as
the ratio of the weight of the substance to the weight of an equal volume
of fresh water.
Specific gravity : “S.G”
Relative Density : “R.D” = density of the substance
density of freshwater

3. Density of Fresh Water
Specific Gravity : “S.G”
Relative Density : “R.D”
Density of the substance
=
Specific Gravity : “S.G”
Relative Density : “R.D” =
Density of the substance
1000
The density of FW = 1000 kg per cu. m
 The relative density of salt water = 1025/1000 = 1.025
 The relative density of oil = 900/1000 = 0.9
 The relative density of fresh water = 1000/1000 = 1

4. Density And Specific Gravity

5. Density And Specific Gravity

6. Density And Specific Gravity

7. Density And Specific Gravity