Kinetic Theory Of Gases

The average molecule speeds should remain constant, that is 1000 fpm

Take two molecules, one at 0 fpm and one at 2000 fpm. Average speed is 1000 fpm. Total kinetic energy KE = .5*m*(2000)^2=2000000*m. In second case, both molecules speed = 1000 fpm: KE=.5*m*2*(1000)^2=1000000*m. Conservation of Energy means that average speed is not constant.

It is a pity that many times silly questions get a lot of answers and help.

Your question is very interesting. and got only one.

Your reasonig must be wrong because the velocity of molecules have, since Boltzman, been measured by MANY diferent means, but it is a good reasoning.

So. Where is he trick?.

1º Can you create a flow of molecules ALL at the same velocity?.

2º If you can, starting from very low temperatures, you need a pefect thermal insulation to avoid the molecules getting energy from outside and have the Maxwel-Boltzman distribution.

3º It seems clear that if all the particles in the container have the same velocity at the begining they will keep it for ever, because the collisions are perfectly elastic.

4º The problem is that your GAS is a very unnatural gas, that may be impossible to create

5º- But may be you can, and then you got something important

Buenas tardes desde Andalucia

chorete

Your conservation equation 1/2mv2=mc(t2-t1) only holds true, if and only if all gas molecules comes to stop at collision. However the real scenario is, gas molecules dont stop after collision yet some of its momentum was converted to heat. The most proper way of having a conservation equation is Delta KE= Delta Q or the change of kinetic energy of gases after collision corresponds a change of temperature of the gas.

However the real scenario is, gas molecules dont stop after collision yet some of its momentum was converted to heat.
Heat is the movement of molecules. Are you trying to say that the molecules get hot from their collisions? I don't think so.

Yap, there's two way to view this scenario. Either you are appling heat to the gas or generating heat by the gas.

Applying heat to the gas, gets every molecule excited until such time average velocity is attained all through, every molecule might not have the same velovity but as awhole or average they could sum up into one lump quantity.

However, the other is, try to compress a gas. You realize heat is being released by the compression. Instantaneously gas molecules are disturbed and molecular velocity changed to a higher level as they bump one another more frequently at the instant as spaces in between decreases, and if the whole system is adiabatic, the same velocity of the molecules of as whole will be retain. Should it be let cool, gas molecules will again find its equilibruim state in which velocity again will decrease in accordance to equilbrium state.

Therefore, suming it up ΔKE of gas molecules = mc ΔT of the gas, that should be it.

Once the molecules get to the vessel's wall they start bouncing in all directions and start colliding against one another in different angles so some molecules increase and others decrease their speeds, but the total average should remain the same.

Of course there is no such a gas but you could take a piece of ice at absolute zero and if given a high speed it will convert into steam after the collition so in the begining all its molecules have the same speed

All this of course is mere theory and considers no friction and perfectly elastic collitions and the vessel should not absorb any heat, buta again these are perfect conditions

"The average molecule speeds should remain constant"

Here's another example: Molecule A is stationary and molecule B travelling at 5, strikes it and the two separate at 90 degree angle (ask any pool player) such that A now has velocity 3, B has velocity 4. Total energy is conserved (25*m/2). Momentum is conserved (cg moves 2.5 units/sec in same direction as original B). Average speed before collision = 2.5. Average speed after collision = 3.5

The short, quick and correct answer to where you are wrong is that you are ignoring the effect of collisions with the walls of the container. The collisions with the walls take place with conservation of energy and momentum. According to your scenario, there are no other gas molecules in the container, so there are no interactions with other gases. The temperature of the vessel gives the vibrational energy of the molecules of the wall, with which the gas molecules equilibrate. You have not stated what is the composition of the gas, that is, whether the gas is made up of a single type of molecule or is a mixture, or whether it has a polyatomic structure allowing internal movement which can partition some energy. Then of course there is the issue that real gasses do not obey the Ideal Gas Law, but have deviations from it.

I recommend that you study the physical chemistry of gasses further. From an engineering viewpoint, the theory of gasses is correct as traditionally stated. The additional deviations arising from quantum considerations and general relativity will not affect the measurable speeds unless you actually have a lab which generates very low or high temperature.

I would also suggest that you learn how to use superscripts and subscripts in writing your equations on this site. It should make comparisons with texts, etc., easier for all of us.