The velocity of 4 gas molecules are given by 1km/s , 3km/s , 5 km/s and 7km/s . Calculate the difference between average and RMS velocity .

Options

A. `0.583 km//s`
B. `0.438 km//s`
C. `0.358 km//s`
D. `0.683 km//s`

Answer

A

Explanation

Average speed = `(1+3+5+7)/4=4km//s`
R.M.S. speed = `sqrt((1^(2)+3^(2)+5^(2)+7^(2))/(4))`
`=sqrt((1+9+25+49)/(4))=sqrt21`
= 4.583
`therefore` The difference between their r.m.s. speed and average speed = 4.583 - 4 = 0.583 km/s.