Class 11 Physics Kinetic Theory | Translational degree of freedom |

**Translational degree of freedom:-**

- Translation means motion of the body as a whole from one point to another.

- For example:
- Consider the oxygen molecule;it has 2 oxygen atoms which are bonded together.
- The 2 oxygen atoms along with the bond are considered as whole body.
- When the body as a whole is moving from one point to another is known as translational.
- Consider a molecule which is free to move in space and so it will need 3 coordinates(x, y, z) to specify its location.
- Therefore it has 3 degrees of freedom.
- Similarly a molecule which is free to move in a plane which is 2 dimensional and so it needs 2 coordinates to specify its location.
- Therefore it has 2 degrees of freedom.
- Similarly a molecule which is free to move in line it needs 1 coordinate to specify its location.
- Therefore it has 1 degree of freedom.

- Molecules of monoatomic gas have only translational degrees of freedom.This means gases which have only one atom.
- For example:-Helium atom it consists of only one He atom.It will have translationaldegrees of freedom.
- Each translational degree of freedom contributes a term that contains square of some variable of motion.
- The variable of motion means the velocity (v
_{x},v_{y},v_{z}). - The term (
**1/2) mv**will contribute to energy.This is Kinetic energy which is involved with the motion of the molecule from one point to another._{x}^{2}

- The variable of motion means the velocity (v

In thermal equilibrium, the average of each such term is (**1/2) k _{B}T**.

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