Concepts Of Physics MCQ Edition [Volume 2]PhysicsKinetic Theory of Gases
Imagine a container is evacuated such that only one molecule of a gas remains inside. Let v_a and v_ rms denote the average speed and the rms speed of the gas respectively.
Options
- Av_a < v_ rms
- Bv_a = v_ rms
- Cv_a > v_ rms
- Dv_ rms is undefined
Correct answer
B. v_a = v_ rms
Step-by-step solution
For a single molecule, let its speed be v . The average speed of the gas is given by v_a = v_i N . Since there is only one molecule, N = 1 , which gives v_a = v . The root mean square speed is given by v_ rms = v_i^2 N . For N = 1 , v_ rms = v^2 = v . Therefore, v_a = v_ rms .