# Can Gas Particles Ever Stop Moving?

1. Nov 2, 2014

### davgonz90

We know that gas particles move very quickly in random motions in whatever container they are in. My question is: assuming that no gas particles ever exit or enter the container, at what point will the gas particles stop moving? From what I think I understand about the second law of thermodynamics, nothing can have an infinite amount of kinetic energy- not even gas particles, right?

P.S. I know that, according to the KMT, gas particles collide and transfer their energy to each other. But even then, can this energy really be transferred forever? Wouldn't this violate the second law? The question is probably very fundamental, but at the moment, it's torquing my brain.

2. Nov 2, 2014

### nuuskur

I have noticed a stirred up bottle of some gas will eventually have the gas sit tightly on the bottom and it wasn't a perfectly isolated container, it was just a plastic bottle. When you open in pool, the balls in the middle get a punch and then they move around chaotically and eventually stop because of friction. Should the end outcome be any different in the container?

3. Nov 2, 2014

### Staff: Mentor

Yes.

No. These are perfectly elastic collisions.

4. Nov 2, 2014

### Staff: Mentor

And how you observed the gas inside of the bottle?

Huh?

No idea what you are talking about, whatever you posted doesn't make any sense.

5. Nov 3, 2014

### nuuskur

Yes, it doesn't make any sense, I thought the gas particles would behave exactly as the "macroscopic" world would, but it doesn't so I stand corrected, thanks.

The gas was smoke in a plastic bottle, came back a few hours later, the smoke was sitting tightly on the bottom part of the bottle. Although, I would have to disregard that as an analogy, because I can't exactly pinpoint whether smoke is a gas or not.
Sorry about the nonsense.

6. Nov 3, 2014

### Staff: Mentor

What you have seen was an aerosol setting down. Nothing to do with the gas.

7. Nov 3, 2014

### DaveC426913

Smoke is, by definition, suspended solid particles of combustion by-product. So yes they are macroscopic, no they are not gas. If you left it long enough, (or if you were able to extract the gas from the bottle), you would have soot on the bottom.

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