Question

The velocity of three molecules are 3V, 4V and 5V respectively. Their rms speed will be

• A. 3/15 V
• B. $\sqrt{\frac{3}{50}V}$
• C. 50/3 V
• D. $\sqrt{\frac{50}{3}}V$

Answer 1

The correct option is D $\sqrt{\frac{50}{3}}V$

V${}_{rms}$( root mean square velocity ) = $\sqrt{\frac{v_1^2+v_{2}2+.......+v_n^2}{n}}$ (standard result)

$v_1$=3V

$v_2$=4V (Given)

$v_3$=5V

V${}_{rms}$=$\sqrt{\frac{3^2+4^2+5^2}{3}}$

=$\sqrt{\frac{50}{3}}$V