Difference between Stress and Pressure
We know that both stress and pressure have the same units, i.e. N/m2; however stress and pressure have a lot of differences between them. They are tabulated below :
| Stress | Pressure |
| Stress can be defined as the internal resistive force to the deformation per unit area. i.e. Internal resistance = force/area | Pressure can be defined as the amount of external force applied per unit area. i.e. Pressure = external pressure/area |
| Due to stress, the pressure will not be developed. | Due to pressure, stress will be developed. |
| Stress can be either a positive or a negative force | The pressure is always a positive force |
| Stress is developed internally. For example, when tensile stress is applied to a block, the interatomic force of attraction tries to bring these molecules to their lattice points, so the restoring force acting inside is the stress. | The Pressure applies externally to the surface. For example, pressure on the ball or pressure on the surface of the liquid. |
| Stress acts on the solids only | Pressure occurs on liquids, fluids and gases |
| Stress may be tensile, compressive and shear | Pressure is always compressive |
| Stress is a vector quantity | Pressure is a scalar quantity |
| Stress is an immeasurable quantity | Pressure can be measured by the measuring device |
Also refer:
