Understanding the **properties of fluids is essential to analyze their behavior in working conditions**.

In this article, we have covered the fluid properties namely mass density, specific weight, specific volume, specific gravity, viscosity, vapor pressure, compressibility and surface tension.

### Mass Density:

*Mass Density (ρ*) is the property of a fluid that is the mass per unit volume.

### Specific Weight:

*Specific Weight (w)* of a fluid is the weight per unit volume.

### Specific Volume:

*Specific Volume (v)* of a fluid is the volume of the fluid per unit mass.

### Specific Gravity or Relative Density:

*Specific Gravity (s)* of a fluid is the ratio of the mass density of a fluid to the mass density of a standard fluid.

### Viscosity:

Viscosity is the property by virtue of which it offers resistance to the movement of one layer of fluid over the adjacent layer.

### Vapor Pressure:

When a liquid is confined in a closed vessel, the ejected vapor molecules accumulated in the space between free liquid pressure and top of the vessel exert a partial pressure on the liquid surface. This pressure in the liquid is known as vapor pressure.

### Compressibility:

The normal compressive stress of any fluid element at rest is known as hydrostatic pressure which arises as a result of innumerable molecular collisions in the entire fluid. The degree of compressibility of a substance is characterized by *bulk modulus of elasticity (B)*.

### Surface Tension:

Surface tension is a measure of the fluid tendency to take a spherical shape, caused by the mutual attraction of the liquid molecules.