Degrees of freedom?

  • The total number of possible independent ways which define the position and configuration of a mechanical system.
  • The total number of independent ways a particle can exchange energy.

Degrees of Freedom (f) for a Rigid Body

  • A rigid body has got six (6) D.O.F, namely 3 translational (X-axis, Y-axis and Z-axis) and 3 rotational (each axis).

Degrees of Freedom (f) of a Gases

Translational Rotational Vibrational
Monoatomic 3 0 0
Diatomic 3 2 1
Triatomic (Linear) 3 2 4
Triatomic (Non-Linear) 3 3 3
  • Vibrational Degree of Freedom –  (3N – (Translatory + Rotational))
  • CV = ftransR/2 + fvibR/2 + frotR/2

NOTE- Heat capacity of mono-atomic gases (inert gases) has only translational D.O.F. so its heat capacity is minimum.


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