1 Density or Mass density:
Density or mass density of a fluid is defined as the ratio of the mass of a fluid to its volume. Thus mass per unit volume of a is called density.
2. Specific weight or weight density:
Specific weight or weight density of a fluid is the ratio between the weight of a fluid to its volume. The weight per unit volume of a fluid is called weight density.
3. Specific Volume:
Specific volume of a fluid is defined as the volume of a fluid occupied by a unit mass orvolume per unit mass of a fluid
4.Specific Gravity:
Specific gravity is defined as the ratio of the weight density of a fluid to the weight density of a standard fluid.