The laws of thermodynamics, when placed in a mathematical format are known as Gibb’s fundamental equation. If both the laws are placed in a single format, it comes down to:

dU – TdS + PdV ≤ 0

dU: Variation in internal energy standards

T: Variation in temperature

dS: Entropy variation standards

P: Pressure level

dV: Volume variation

In either case, working body is simple and there is no other force acting on it apart from gravitational force. When theoretical structure is considered, both these laws are taken into consideration apart from zeroth law, which has temperature as an issue and third law that makes use of free energy standards.

**Links of Previous Main Topic:-**

- Open system and control volume
- Conversion of work into heat
- Introduction to carnot cycle
- Clausius inequality entropy and irreversibility introduction
- Reversible adiabatic paths do not intersect
- Clausius theorem
- Entropy
- Entropy temperature plot
- Clausiuss inequality
- Entropy change in an irreversible process
- Principle of increase of entropy
- The degree of irreversibility of and irreversible process
- Summary of first and second law by clausius
- Practical use of entropy principle
- First law and second law combined

**Links of Next Mechanical Engineering Topics:-**