Monday, November 10, 2014

Degree of freedom and Law of the Equipartisien energy

Degree of  Freedom

It is the ability of a gas molecule which can move freely with respect to the available circumstances.The degree of the freedom of a gas molecule depends on the nature of the gas molecule.

The molecule of a mono atomic gas can have only translatory motion and hence it has 3 degree  of the freedom along its x-axis y-axis and z-axis.

Diatomic gas molecule can have not only a translatory motion but also rotatory motion along two other possible axis. Thus it can have five degrees of freedom.

Tri/poly atomic gas molecule can have translatory motion, vibratory motion as well as a rotatory motion.

Law of the Equipartisien energy:

As per this law the average kinetic energy per each degree of the freedom per molecule is fixed.

Basing on this concept we can find the specific heat of a gas at constant volume, at constant pressure and the ratio of their specific heats as shown below.It can be also proved easily that in all the supplied heat energy of hundred percent,around 60% is used to increase the internal energy in the case of mono atomic gas.

Basing on the law of  Equipartisien energy we can also find the ratio of the specific heats of the gases at constant pressure and volume and it can be proved that about the total heat energy supplied around 71% is used to increase its internal energy and the remaining 29% is used to do the additional work.

As per the law of  Equipartisien energy we can find the ratio of the specific heat of the gases for tri atomic gas at constant pressure and volume as shown below. It can we also proved that out of the total supplied heat energy 75% of the heat energy is used to increase the internal energy and only the remaining 25% is used to do the external work.

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