Explanation on basic laws of thermodynamics

Thermodynamics is the study of heat parameters such as temperature, entropy and pressure. Heat is: energy form; it can be converted on form to another form; it satisfies laws of conservation of energy . Temperature is a measurement of kinetic energy of the molecules in the body; generally, internal energy in the body is measured as sum of potential and kinetic energies.

When the heat is transferred to the body, molecules in the body gets kinetic energy; as a result, temperature of the body increases; so, we can say that heat is proportional to the temperature.

Entropy, is a measurement of order to disorder of molecules in the system; its concept can be understood by comparing the heat with absolute temperature. In isothermal process, we keep the temperature at constant value; but, heat energy transfers to the system; then, entropy increases.

Like newton laws of motion in dynamics, in thermodynamics we have laws of thermodynamics. They are:
i)Zeroth law of thermodynamics;
ii)First law of thermodynamics;
and iii)Second law of thermodynamics.

The total thermodynamics subject deals with the above three laws. They are

a)Zeroth law of thermodynamics:

If two bodies A and B are thermally equilbrium with another body C, then, automatically, A and B bodies are thermally equilbrium with each other. Depending on this principle, thermometer works; thermometer bulb, mercury and we are three bodies; when the thermometer touches us, thermometer bulb and mercury are in thermally equilbrium with our body; after, thermometer bulb and mercury becomes thermally equilbrium with each other. This zeroth law of thermodynamics tells the definition of thermal equilbrium. But, the process of reaching to thermally equilbrium is explained in first and second laws of thermodynamics.

b)First law of thermodynamics:

In first law of thermodynamics, we use the terms such as internal energy, heat and work. These are linked in first law of thermodynamics. Suppose, After cooking completed, we listen a whistle for the top of a cooker. To get whistle, there is some work to be done inside the cooker. Where the heat comes from? answer is heat; Heat gives some internal energy to the substance in the cooker. As result, the internal energy causes to vibrate the upper part of the cooker. As a result, we listen the whistle.

So, we can say that applied heat to the system is equal to sum of internal energy due to the heat and work done by the sytem. This is the first law of thermodynamics. First law of thermodynamics represents the conservation of energy.

c)Second law of thermodynamics:

This law supports the principle of working of Carnot''''s engine. According to Kelvin-Plancks statement, whatever heat extracted from hot reservior cannot be converted all into work. Some heat will be exhausted to cold reservior. If the total extracted heat converts into work, then the heat engine becomes ideals one. It is impossible to extract heat from cold body to heat body unless an external agency is used. Second law of thermodynamics said in terms of entropy as it will be increase or static while cyclic process is going on. From second law of thermodynamics, entropy is defined as measure of disorder of a system