Q. Six molecules speeds 2 unit, 5 unit, 3 unit, 6 unit, 3 unit, and 5 unit respectively. The rms speed is
A) 4 unit
B) 1.7 unit
C) 4.2 unit
D) 5 unit
Explanation
(c) We have $v_{rms} = \sqrt{\frac{v_{1}^{2} + v_{2}^{2} + ... + v_{n}^{2}}{n}}$
= $\sqrt{\frac{4 + 25 + 9 + 36 + 9 + 25}{6}}$
= $\sqrt{\frac{108}{6}} = \sqrt{18} = 3\sqrt{2} = 3 \times 1.414 = 4.242$ unit.
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.