Open Systems

[MarkE]

No-its not basic thermodynamics,it's basic physics. For every action there is an equal and opposite reaction=what you loose in one,you gain in another.

You are misapplying Newton's Third Law.

The other fact that supports this is-->you simply cannot loose(destroy)energy.

That's right you can't destroy it and you cannot create it either.  When you convey energy by doing work on the external system, you lose that energy from the internal system.

Heat energy being disipated into the enviroment is not looseing energy,it is transfering energy.

That's right.

Well insulated pipes and tanks will see this transfer brought down to a minimum.

All the insulation in the world is not going to prevent the internal energy loss that results from performing work on the external system.

No-it is not dead wrong. When the gas is used to apply a force to a resistance,the resistance applies the very same amount of force on the gas-->equal and opposites.

If the forces are equal then the system is in equilibrium.  When the forces are unequal then Newton's Second and Third Laws both come into play:  The system accelerates according to the difference in force divided by the mass.

You also assume (incorrectly)that the gas cools as it leaves the pressure vessel-->it dose not.

But it does.  This is really basic thermodynamics.  Do your experiments, show your measurements and then we can talk.  Boyle's Law which is a subset of the ideal gas law applies here.  You don't believe that.  We have covered it many times.  A game of:  "Yes it is.  No it isn't." is not productive.

You asked why the outlet of a pressure vessel gets cold when the gas is flowing out through that outlet,well that is because the flowing gas is drawing out the stored heat within that outlet nozzel,and thus,the nozzel freezes.

The reason that a vessel of compressed gas cools as gas is released is due to Boyle's Law.

This can only mean that the gas leaving the pressure vessel is hotter than that stored within the pressure vessel,but misconseptions come in regards to the temperature of that gas,as it mixes with the ambiant air once it leaves the pressure vessel.

The vessel cools as the gas is released.  We can start with the vessel in absolute thermal equilibrium with the outside atmosphere and this will always be true.  I know you don't believe this, despite what you can find out with a $3. can of dusting spray and a your hand as a temperature sensor.  So. do your experiments.

And what makes you think i havnt already ?.

I make no assumptions about what you have or have not done.  When you report your data we can talk about how you performed your experiments, the measurement methods and the data.  You haven't reported those things so we are not in a position to talk about them.

Im simply upgrading all my equipment,so as a clear and precise result can be shown. Everything will be automated-->no hands will be used that could be considered to be contributing to the end result's.

I for one appreciate that you put time and effort into your experiments.  I think that you really want to learn the truth.

Cost of this project will be around the $500.00 mark. I simply would not spend this type of money on something i hadnt already tried.

You have your expectations.  That is all fine and well.  We will see how you go about your tests, and what data you end up with in the end.

[Jimboot]

When you convey energy by doing work on the external system, you lose that energy from the internal system

I ask this question in all seriousness Mark, as I do appreciate your stringent adherence to real proof as you define it. I do disagree with you there on a couple of points.


Although I really do appreciate you not taking things personal even when provoked (with some exceptions)


As a complete novice here is something I don't understand that I really would appreciate your position on the Big Bang theory ( not the tv show) the situation you describe above does not seem to fit.

[MarkE]

I ask this question in all seriousness Mark, as I do appreciate your stringent adherence to real proof as you define it. I do disagree with you there on a couple of points.


Although I really do appreciate you not taking things personal even when provoked (with some exceptions)


As a complete novice here is something I don't understand that I really would appreciate your position on the Big Bang theory ( not the tv show) the situation you describe above does not seem to fit.

I think that the Bernadette and Amy characters are masterful.  Oh right, not the TV show.

There are some things on which we presently have a very weak or no grasp.  One of them is what was there before there was anything.  The strong evidence for the Big Bang is the microwave background.  What caused there to be a primordial hot stew of stuff and what caused it to spew forth and start cooling is not something for which I have seen a satisfying explanation.  The very rude guy who likes to say that a bunch of great minds were full of hooey may be somewhat right about that.  The trouble is that greater minds or at least minds with better insights seem to be lacking.  QM is very strange stuff, so much so that it's easy to get the idea that it's analagous to Ptolemy's epicycles all over again:  A set of rules that in a very complicated way makes accurate predictions within its limits.  When it comes to QED the predictions are really, really good.  That still doesn't mean that QED is the right idea, but it sure makes it very practical to use.

Maybe someone will come along with something far more elegant that ties to a more fundamental understanding of what makes the universe tick as opposed to describing the way that things about it appear to tick.  If we don't get that, it would at least be nice to discover something that makes QM and QED less weird.  In the interim, we muddle on.

[Jimboot]

Mmmm thanks for taking the time to respond. btw I frigging hate the tv show.

[tinman]

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That's right you can't destroy it and you cannot create it either.  When you convey energy by doing work on the external system, you lose that energy from the internal system.

You loose that energy to where Mark?. A reminder that the heading of this thread is !!open systems!!. The energy is not lost,and regardless wether or not there is a resistance against the ram,the energy state of the gas within that ram will not change,in fact,it gains energy in the way of heat when the ram is made to do work.

That's right.All the insulation in the world is not going to prevent the internal energy loss that results from performing work on the external system.

There is no internal loss when the gas is performing external work,there is a gain in heat energy within the cylinder(the gas) when that ram is made to do work.

If the forces are equal then the system is in equilibrium.  When the forces are unequal then Newton's Second and Third Laws both come into play:

Every action has an equal and opposite reaction-->the forces are always equal in opposite directions. You cannot have two apposing forces that are unequal,otherwise perpetual motion would be possable. When you have what you call two unequal forces,you still only have a net force in one direction. This net force that is used to accelerate a mass is in the opposite direction to and equal to the accelerated mass-thus there is no unequal forces.

The reason that a vessel of compressed gas cools as gas is released is due to Boyle's Law.The vessel cools as the gas is released.  We can start with the vessel in absolute thermal equilibrium with the outside atmosphere and this will always be true.  I know you don't believe this, despite what you can find out with a $3. can of dusting spray and a your hand as a temperature sensor.

I have never said that i dont believe the vessel will cool when the gas is released,in fact,i have said the opposite-->so not sure where you came up with that statement. What i am saying is that the gas temperature in the ram will increase when the ram is made to do work-external work. So while the energy within the vessel reduces,the energy within the ram increases by the same amount-no energy is lost within the closed system. The energy stored at this time(after the ram has performed work on the external system) within both the vessel and ram is the very same amount as we started with within the vessel.