All Problems

Kinetic theory of gases. Boltzmanns Law and Maxwell distribution

Problem 2.90

Find the fraction of molecules whose velocity projections on the \(x\) axis fall within the interval from \(v_{x}\) to \(v_{x}+d v_{x},\) while the moduli of perpendicular velocity components fall within the interval from \(v_{\perp}\) to \(v_{\perp}+d v_{\perp} .\) The mass of each molecule is \(m,\) and the temperature is \(\bar{T}\).

Reveal Answer
dN/N=(m2πkT)3/2emv2/2kT2πvdvdvxd N / N=\left(\frac{m}{2 \pi k T}\right)^{3 / 2} \mathrm{e}^{-m v 2 / 2 k T} 2 \pi v_{\perp} d v_{\perp} d v_{x}