I Question about the Zeroth law of thermodynamics and Equlibrium

[MatinSAR]

TL;DR Summary

Question about zero law of thermodynamics and equilibrium

I know that if 2 systems A and B are in equilibrium their coordinates doesn't change. Systems are not complicated and be fully described using two separated coordinates X and Y.

What will happen if I seprate them using an adiabatic wall? Their coordinates start to change but I cannot understand why.

 

[DrClaude]

I don't understand your use of the word "coordinates" here. Can you expand?

 

[MatinSAR]

I don't understand your use of the word "coordinates" here. Can you expand?

I've read about them in "Heat and Thermodynamics by M. W. Zemansky".
By coordinates I meant quantities that describe a state of a system like: Temperature, Pressure, Volume.

Edit : Adding a picture of the book.

 

[Arjan82]

Interesting, I know these as 'state variables', not coordinates.

If you separate two systems that are at first in equilibrium, then their state may or may not drift away from each other. This depends entirely on the surroundings they are in. If there is a net flow of mass or energy over the surface by which you separate the system, then this energy or mass flow stops after the separation. This will then influence the state of both systems, and their respective states will likely drift away from each other.

 

[MatinSAR]

If you separate two systems that are at first in equilibrium, then their state may or may not drift away from each other. This depends entirely on the surroundings they are in.

I understand ... Thank you.