Thermodynamics is a branch of physics that deals with the relationship between properties such as energy, heat, work, pressure, density, temperature, etc. on a system.

There are three thermodynamic system, open, closed and isolated:

• Open system freely exchanges energy and matter with its surroundings. 
• Closed system exchanges only energy with its surroundings, not matter.
• Isolated system keeps the energy and matter within the system and everything else out. No transfer in or out.

For formula info see Nomenclature & Symbols for Engineering, Mathematics, and Scienceor

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