Difference Between Stress And Pressure

Stress and pressure are both forces that are mistaken as the same. However, stress is referred to as the material property and it occurs due to the result of the pressure exerted. On the other hand, pressure is defined as the physical force applied to an object. In simple, pressure is the amount of force that is applied per unit area. Pressure is majorly noticed as the unique property of thermodynamics and serves as a cause for stress. 

What is Stress?

Basically, stress is the intensity that measures the force of internal resistance. This resistance force, however, is formed at a specific location as a result of the application of force. The amount of internal force required per unit area. In simple we can say the amount of force per unit area experienced by a material is termed stress.

How It’s Measured?

Stress is typically measured using strain gauges, which are devices that measure the amount of deformation or strain in a material in response to an applied force.

Strain gauges are often attached to the surface of a material, and as the material is subjected to stress, the gauge deforms, producing a measurable change in electrical resistance. This change in resistance can be used to calculate the stress on the material.

The SI unit of stress is pascal (Pa), which is equal to one newton per square meter (N/m²). 

Formula

The stress of a body is given by the formula, 

σ= (−) F/A, 

where, −F is noted as the internal resistive force.

What is a Pressure?

The amount of force applied per unit area is called Pressure. The intensity at which the external forces act at a particular point. This is the number of forces applied per unit area that are external in nature. The mathematical representation of this formula is Pressure = Force / Area.

How It’s Measured?

Pressure is typically measured using pressure sensors, which are devices that measure the amount of force applied to a given area. Pressure sensors are often used in hydraulic and pneumatic systems to monitor and control pressure levels. 

They can be based on a variety of sensing technologies, such as piezoelectric, capacitive, or strain gauge sensors, and can be designed to measure pressure in a wide range of applications, from high-pressure gas pipelines to low-pressure pneumatic systems.

The SI unit of pressure is also the Pascal, but it can also be expressed in other units, such as pounds per square inch (psi) or atmospheres (atm).

Formula

The pressure is represented as, p = F/A, 

where F is denoted as the positive directive force. 

Difference Between Stress and Pressure

Stress	Pressure
The internal resistive force to the deformation per unit area is termed stress.	The amount of force applied per unit area is termed as pressure.
Stress can be represented as (strain) / (Young’s modulus)	Pressure can be mathematically represented as (force) / (area)
Stress can be either a positive or a negative force.	The pressure is always a positive force.
Stress may be tensile, compressive, and shear.	Pressure is always compressive.
Stress is a material property.	Pressure is a unique property of thermodynamics or physics.
Stress develops internally.	The pressure exerts externally.
There is no device to measure stress (not a measurable quantity). Stress is calculated by measuring strain or elongation.	The pressure is physically measured (measurable quantity) using pressure gauges, manometers, and other pressure-measuring devices or instruments.
The magnitude of stress at a point in a different direction is different.	The magnitude of the pressure at a point in all directions remains the same.

Conclusion

In summary, stress and pressure are related but different concepts, with stress measuring the internal resistance of a material to an applied force, and pressure measuring the external force exerted on a material. They are typically measured using different types of sensors, with stress being measured using strain gauges and pressure being measured using pressure sensors.

FAQ’s

Q1. Define pressure.

Ans: Pressure is defined as the amount of force applied per unit area.

Q2. What is stress?

Ans: Stress refers to the force exerted per unit area experienced by a material.

Q3. What are the different units of pressure?

Ans: The pressure units most commonly used are SI units, which typically report atmospheric pressures in kiloPascals.

Q4. Is pressure always compressive in nature?

Ans: Pressure always acts normally on a surface, and it is always compressive in nature. It needs only its magnitude. Hence, the direction is always normal to the surface, and the magnitude of the force acting depends upon the particular area acting.