Question
At what temperature will the average velocity of oxygen molecules be sufficient so as to escape from the earth? Escape velocity from the earth is 11.0km/sec and the mass of one molecule of oxygen is 5.34 × 10-26kg (Boltzmann constant k = 1.38 × 10-23 Joule/K).

Answer

We know $\frac{1}2{}\text{mv}^2=\frac{3}{2}\text{kT}$ or $\text{T}=\frac{\text{mv}^2}{3\text{k}}$

Here, $\text{m}=5.34\times10^{-26}\text{kg}$

$\text{v}=11.0\text{km/s}=11\times10^3\text{ms}^{-1}$

$\text{k}=1.38\times10^{-23}\text{Jk}^{-1}$

$\therefore\text{T}=\frac{5.34\times10^{-26}\times(11\times10^3)^2}{3\times1.38\times10^{-23}}$

$=1.56\times10^5\text{K}$

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