Difference between pressure and stress

In summary: Beyond that simple relationship, what might constitute a good intuitive way to distinguish these two concepts?There is no simple or universal way to differentiate between pressure and stress- it largely depends on the context in which you are using the term.
  • #1
PerpStudent
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Both pressure and stress are defined in terms of force per unit area. Beyond that simple relationship, what might constitute a good intuitive way to distinguish these two concepts?
 
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  • #2
They are basically the same thing and the terms used tend to reflect context rather than physics. You would use 'Stress' when dealing with stretching etc, pressure when dealing with gases etc.
Similar 'problems' occur with Newton.metres which can mean work or energy (Joules) or moment as in turning effect and torque
 
  • #3
truesearch said:
They are basically the same thing and the terms used tend to reflect context rather than physics. You would use 'Stress' when dealing with stretching etc, pressure when dealing with gases etc.
Similar 'problems' occur with Newton.metres which can mean work or energy (Joules) or moment as in turning effect and torque

Nm is strictly a unit of Moment. The 'Newtons times metres' that is used to calculate Work is the Scalar Product of two Vectors (Force and Displacement) and Nm should never be used to describe Work of Energy.

Pressure and stress, however, are totally equivalent and it's only the context that determines which term you want to apply to a situation. (It's not really a "problem")
 
  • #4
PerpStudent said:
Both pressure and stress are defined in terms of force per unit area. Beyond that simple relationship, what might constitute a good intuitive way to distinguish these two concepts?

Stress is a little more general than pressure- one intuitive way to think about stress is to think about how a square can be deformed. The square can be made larger or smaller (uniform expansion/compression), but also be sheared into a rhombus shape (and combinations of expansion with shear as well).

'stress' is the most general way to describe any deformation, while pressure is restricted to the uniform expansion/compression. Mathematically, pressure is the isotropic component of the stress tensor.
 
  • #5


While both pressure and stress are indeed defined as force per unit area, they represent different types of forces and have different effects on materials. Pressure is a force that is exerted uniformly in all directions, while stress is a force that is exerted on a specific area or point in a material.

A good intuitive way to distinguish between the two concepts is to think of pressure as a force that is applied evenly over a large area, like a balloon being inflated. On the other hand, stress can be thought of as a localized force that can cause deformation or damage to a material, such as a weight being placed on a small point on a table.

Another way to differentiate between pressure and stress is to consider their sources. Pressure is often caused by external forces, such as the weight of a fluid or gas, while stress can be caused by both external and internal forces, such as tension, compression, or bending.

In summary, while both pressure and stress involve force per unit area, pressure is a uniform force that acts on a large area, while stress is a localized force that can cause deformation or damage to a material. Additionally, pressure is typically caused by external forces, while stress can result from both external and internal forces.
 

What is the difference between pressure and stress?

Pressure is a force applied per unit area, while stress is a measure of the internal forces within a material. Pressure is typically measured in units of force divided by area (such as pounds per square inch or pascals), while stress is measured in units of force divided by area (such as pounds per square inch or pascals), while stress is measured in units of force divided by area (such as pounds per square inch or pascals).

How are pressure and stress related?

Pressure and stress are related in that they both involve force being applied to a material, but they are not the same thing. Pressure applies to the surface of a material, while stress applies to the internal forces within the material. In some cases, pressure can lead to stress within a material, but this is not always the case.

What are some examples of pressure?

Examples of pressure include the weight of a book on a table, the force of air in a tire, and the pressure exerted by water at the bottom of a swimming pool. Pressure can also be caused by physical forces, such as a person stepping on a surface or a strong wind pushing against a structure.

What are some examples of stress?

Examples of stress include the tension on a bridge caused by the weight of cars, the compression on a building's foundation caused by the weight of the structure, and the shear stress on a rope being pulled from both ends. Stress can also be caused by non-physical factors, such as emotional or psychological stress.

How can pressure and stress be measured?

Pressure can be measured using instruments such as pressure gauges and manometers, which measure the force applied per unit area. Stress can be measured using strain gauges, which detect the deformation of a material under stress. Both pressure and stress can also be calculated using mathematical equations and formulas.

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