Kinetic Theory Of Gases Question 23

Question: N (< 100) molecules of a gas have velocities 1, 2, 3,…….. N km/s respectively. Then ratio of rms speed and average speed is

Options:

A) 1

B) $ \frac{\sqrt{( 2N+1 )( N+1 )}}{6N} $

C) $ \frac{\sqrt{( 2N+1 )( N+1 )}}{6} $

D) $ 2\sqrt{\frac{2N+1}{6( N+1 )}} $

Show Answer

Answer:

Correct Answer: D

Solution:

[d] $ V _{rms}=\sqrt{\frac{1^{2}+2^{2}+….+N^{2}}{N}} $

$ =\sqrt{\frac{N( N+1 )( 2N+1 )}{6N}} $

$ V _{mean}=\frac{1+2+….N}{N}=\frac{N( N+1 )}{2N} $