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 $5.34 \times 10^{-26}kg$ (Boltzmann constant $k = 1.38 \times 10^{-23} Joule/K)$.

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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