Maxwell speed distribution

The probability that speed of a moleculae of mass m lies in the range v to v+dv is given by

$P(v)dv=4\pi v^{2}dv\left({\frac {m}{2\pi k_{B}T}}\right)^{3/2}\exp(-mv^{2}/2k_{B}T)$

References

1. J. S. Rowlinson "The Maxwell-Boltzmann distribution", Molecular Physics 103 pp. 2821 - 2828 (2005)