Difference Between Pressure and Stress

There are several key distinctions between stress and pressure, but these are also terms that are often mistaken for each other. Pressure may primarily be defined as the amount of force per unit area exerted. Stress refers to materials amount of force exerted per unit area, This is a term as stress is uniquely more different from pressure.

What is pressure?

The pressure is an inherent property, and it is often fluid-related. It depends on the transfer of momentum on a micro-scale between the atoms of a liquid or gas volume.

What is stress?

Stress is a consequence of the property of a body undergoing arbitrary deformation to return to its own reference state, stress is produced whenever a force is generated to simplify.

Difference between Pressure and stress:

  • Pressure can be defined as the amount of force per unit area applied While stress can be defined as the internal resistive force to the deformation per unit area.
  • In pressure stress is developed internally, while stress, the pressure is exerted externally, 
  • Due to pressure, stress will be developed. While due to stress, the pressure will not be developed.
  • The pressure is physically measured using pressure gauges, a manometer, and other pressure measuring devices or instruments, while the stress is no device to measure stress. stress is calculated by measuring strain or elongation.
  • The pressure is always a positive force, while stress can be either positive or a negative force.
  • The pressure is always compressive, while the stress is tensile, compressive, and also shear.
  • The pressure is a unique property of thermodynamics or physics, while stress can be represented as strain/ youngs modulus.
  • The magnitude of the pressure at a point in all the directions remains the same,  The magnitude of stress at a point in a different direction is different.
  • The pressure is independent of the area of the contact surface area. It remains constant and does not vary with change in surface area, while the stress varies with change in surface area.
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