# Print ViewEquipartition Theorem and Microscopic Motion

1. Nov 13, 2007

What is the typical rotational frequency f_rot for a molecule like N_2 (nitrogen) at room temperature (25 C)? Assume that d for this molecule is 1 angstrom = 10^{-10} m. Take the atomic mass of N_2 to be 4.65 * 10^{-26} kg.
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I know that the rms angular speed which is the root mean square (rms) of the x component of velocity of the gas particles is = sqrt(2k_B(T)/(m(d^2))) where k_B is the Boltzman constant 1.38*10^-23 J/K.

Last edited: Nov 14, 2007
2. Nov 14, 2007

### Staff: Mentor

Think about moment of inertia. How much of the energy is distributed in rotational motion versus translational motion?

Or assuming the rotational motion comes from collisions based on a translational speed, how does one transform the typical translational speed into a rotational velocity?

3. Nov 14, 2007

what do i do with the rotational speed that i calculated to get rotational frequency??'

molecule has moment of inertia I about the axis and is rotating with angular velocity omega about that axis with associated rotational kinetic energy (1/2) I omega_x^2

Last edited: Nov 14, 2007
4. Nov 14, 2007