Recent content by MikeW

The 'arriving at top' line does not start at zero probability because the gas molecule is slowed on the way up, this changes the distribution. The distributions might not be precisely right, the bigger picture of this is if there is ANY consistent shift in typical velocity (what ever the initial...

Hi MTB, I think this has being address in answering Ron's comment The temperature used in the formula is that of the surface that the gas molecule interacts with

I think a single gas molecule can have a velocity distribution over time, if interacting with a container. I do not know the precise distribution when velocity of gas molecule is affect only by container, not other gas molecules, but M-B seemed a good starting point. No collisions, please read...

Hi Ron, thanks for your comment. Have thought about it quite a bit. I agree that for coldest cases, there is no interaction with the top, I think this is the same point Jartsa is making in comment #29. I think when considering energy transfer, the change in speed distribution (top to bottom or...

Hi Peter, thank you for your comment. As initially stated: Not a group of molecules, a single SF6 molecule. Not at some altitude: a) Initial M-B Distribution assumed at bottom for upward vector, reduces velocity due to gravity, different distribution at top BEFORE touching top surface. a)...

Sorry, there is an error in the graph to do with the spread, forgot to do the energy adjust for initial speed (ie reduction/gain less than 140m/s as intital velocities increase). Will change and repost. Will affect, spread, not general idea.

I used the Maxwell–Boltzmann distribution function. I adjusted the probabilities for the upward and downward case due to gravity (+/- 140m/s for 1000m). As no gas molecule traveling upward with velocity less than 140m/s can reach the top, the probabilty for this was scaled to keep the area under...

The example I gave was 1000 metres NOT 1000 Kilometres. I agree you would need a very high temperature in the bottom surface to obtain the velocity (for gas the molecule) needed to reach a 10^6 metre height. (1000km or 1000m?) INITIALLY the gas molecule may (depending on initial velocity) get...

I agree, for shorter lengths of pipe that, due to the distribution of speeds for a gas molecule, sometimes the single gas molecule will heat the top. But if you look at the probability distribution of speeds, it is no longer a Maxwell–Boltzmann distribution at top and bottom. If I have a pipe 1...

Correction: 7m/s at bottom for a 2.5m pipe

I agree, in this situation, which is different to the one I am describing, there will be no interaction with the top, PROVIDING the bottom is near 0 K so it cannot initially add energy to the gas molecule. The molecule in your set-up would have velocity around 3.5m/s at bottom for a 2.5m pipe...

I assume the pipe walls are the means for the warmer bottom to transfer to the top of the pipe, is there an another means? The thought experiment does not require pipe walls, the pipe was used to bring it back to a real world experiment. If you look at it in the single molecule of...

I think it would gain kinetic energy at the ceiling, do you think it would lose kinetic energy?

Fair comment; I will use 'kinetic energy' for the single molecule case, instead of temperature. I do not think it changes the concept of the single molecule thought experiment though.

I find this a really interesting idea. To put this in the context of my thought experiment, there is only one molecule of nitrogen in the entire Earth atmosphere and no solar radiation or solar wind. Would you expect the molecule to reach escape velocity? or would you expected it to reach a...