Four laws of thermodynamics

Four laws of thermodynamics

The so-called Zeroth Law is a bit more fundamental than the other Three Laws. It came into being after the Three. It essentially says that if each of two systems is in equilibrium with a third system, the first two are in equilibrium with one another. 

The First Law basically says that energy or matter can neither be created nor destroyed. In terms of the machine, this meant that the total energy output (work by the machine) is equal to the heat supplied. In other words, the change in the internal energy of a closed system is equal to the heat added to the system minus the work done by the system. Because the system operates in the real world, some energy always escapes into the outside world, thus leading to both inefficiency and the Second Law, which was generated to cover the so-called flaw in the First Law. 

The Second Law essentially says that it is impossible to obtain a process where the unique effect is the subtraction of a positive heat from a reservoir and the production of a positive work. Energy exhibits entropy. It moves away form its source. In this sense, energy or heat cannot flow form a colder body to a hotter body. You cannot keep a continual flow of heat to work to heat to work without adding energy to the system. In machine terms, you have to add energy to get more work, and the ratio of heat to work will never equal 100% due to energy expanding away from its source. 

The Third Law explains this further. It says that all processes cease as temperature approaches absolute zero. This is the temperature at which molecules cease movement, cease producing kinetic energy. In other words, there is no energy. 

Here is a video which helps you to understand the topics easily.

Please drop a comment below if you have any doubt.

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Best book for thermodynamics : P.K. Nag