Welcome to Physics Problems Q&A, where you can ask questions and receive answers from other members of the community.

Mean free path of ideal gas

2 votes

There's a box with a wall in mid dividing it in two sections, each filled with same ideal gas in both sections at 150 K in one section and at 300 K in another. How am I supposed to calculate ratio of mean free paths (MFP)in 2 sections?

My attempt: MFP ~ Volume / Number of particles

              => MFP ~ Temperature / Pressure

Now, Assuming pressure to be same on both sections, ratio must be half. But that is incorrect. Why?

asked Aug 7, 2018 in Physics Problems by Tachyonprince (120 points)
$MFP \propto T/p$ is correct. Perhaps your assumption that the pressure is the same in both section is incorrect. If there is nothing in the question to suggest what assumption should be made about pressure, the question is faulty and cannot be answered.
The ratio should be 1 because at constant volume $T/p$ is constant.
@Restack $T/p=V/Nk$ would be the same if the two sections contain the same number of molecules $N$. But we are not told that$N$ is the same in the two sections.

Please log in or register to answer this question.