An ideal gas consisting of molecules of mass `m` with concentration `n` has a temperature `T`. Using the Maxwell distribution function, find the number of molecules reaching a unit area of a wall at the angles between `theta` and `theta + d theta` to its normal per unit time.

Explanation

The number of molecules reaching a unit area of wall at angle between `theta` and `theta + d theta` to its normal per unit time is.
`dv = int_(v = 0)^(v = oo) dn (v) (d Omega)/(4 pi) v cos theta`
=`int_0^oo n((m)/(2 pi kT))^(3//2) e^(-mv^2//2 kT) v^3 dv sin theta cos theta d theta xx 2 pi`
=`n((2 kT)/(m pi))^(1//2) int_0^oo e^(-x) xdx sin theta cos theta d theta = n((2 kT)/(m pi))^(1//2) sin theta cos theta d theta`.
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