State postulate for incompressible substance

[Signature]

State postulate for a simple compressible system is completely specified by two independent intensive properties.
But what about state postulate for a incompressible system.
Why it is not so important?

 

[Chestermiller]

State postulate for a simple compressible system is completely specified by two independent intensive properties.
But what about state postulate for a incompressible system.
Why it is not so important?

Please identify what you consider an incompressible system.

 

[Signature]

Please identify what you consider an incompressible system.

just considering only liquids specifically water

 

[Chestermiller]

just considering only liquids specifically water

Liquid water is compressible, so it still takes specification of two intensive properties to define its thermodynamic equilibrium state. See the phase diagram for water.

 

[Signature]

Liquid water is compressible, so it still takes specification of two intensive properties to define its thermodynamic equilibrium state. See the phase diagram for water.

Let it be, but, in most cases especially fluid mechanics we treat water as an incompressible liquid. Anyway if there is an incompressible substance, what are the basic properties which are required to completely specify its state. Why no textbooks did mention about the state postulate of incompressible substances?

 

[Chestermiller]

Let it be, but, in most cases especially fluid mechanics we treat water as an incompressible liquid. Anyway if there is an incompressible substance, what are the basic properties which are required to completely specify its state. Why no textbooks did mention about the state postulate of incompressible substances?

It's certainly mentioned in thermodynamics books. Look up Poynting Correction.

Chet

 

[Chestermiller]

But Poynting correction is for real gases. But I want to know about incompressible substance.

I'm sure you are aware that there is no such thing as a completely incompressible liquid.

 

[Signature]

It's certainly mentioned in thermodynamics books. Look up Poynting Correction.

Chet

Ok sir. Then what about the state postulate for solids

 

[Signature]

Ok sir. Then what about the state postulate for solids

How can we define the state of solids

 

[Chestermiller]

For homogeneous isotropic single phase solids, two intensive variables are still required. Incidentally, for solids, Hooke's law in 3D automatically has compressibility built into the relationship.

Chet