Merged DDWFTTW in a “Real” Wind

[CORed]

A Stirling engine is a heat engine operating by cyclic compression and expansion of air or other gas, the working fluid, at different temperature levels such that there is a net conversion of heat energy to mechanical work.[1][2]
Like the steam engine, the Stirling engine is traditionally classified as an external combustion engine, as all heat transfers to and from the working fluid take place through the engine wall. This contrasts with an internal combustion engine where heat input is by combustion of a fuel within the body of the working fluid. Unlike a steam engine's (or more generally a Rankine cycle engine's) usage of a working fluid in both its liquid and gaseous phases, the Stirling engine encloses a fixed quantity of permanently gaseous fluid such as air.

Laughs.


http://physicsworld.com/cws/article/news/26939



Because I am right.

Because you're so funny when you're wrong.

 

[CORed]

Getting motion from molecular motion is not related to Maxwell's Deamon.
Think surface tension. Surface energy.

It's a similar problem. You need a mechanism for selecting between molecules moving in different directions, as opposed to molecules moving at different speeds.

 

[CORed]

Then what will satisfy you? A note from The Queen?
It is RMS, and that mean YOU ARE WRONG: live with it.

He's not wrong. It's simply that even a lot of scientists are less than rigorous in differentiating between velocity and speed.

 

[humber]

Because you're so funny when you're wrong.

Aw..diddums.

Steeerike!

Examples of everyday heat engines include the steam engine, the diesel engine, and the gasoline (petrol) engine in an automobile. A common toy that is also a heat engine is a drinking bird. Also the stirling engine is a heat engine. All of these familiar heat engines are powered by the expansion of heated gases. The general surroundings are the heat sink, providing relatively cool gases which, when heated, expand rapidly to drive the mechanical motion of the engine.

 

[humber]

He's not wrong. It's simply that even a lot of scientists are less than rigorous in differentiating between velocity and speed.

Your own personal Pangloss.

Steeerike!

Speed of molecules

From the kinetic energy formula it can be shown that

[latex] v_{rms}^2 = \frac{3RT}{\mbox{molar mass}}[/latex]

with v in m/s, T in kelvins, and R is the gas constant. The molar mass is given as kg/mol. The most probable speed is 81.6% of the rms speed, and the mean speeds 92.1% (distribution of speeds).

 

[Llyricist]

Wind speed is never 0, in fact, it can never be less than about 500 m/s.

 

[CORed]

Aw..diddums.

Steeerike!

Examples of everyday heat engines include the steam engine, the diesel engine, and the gasoline (petrol) engine in an automobile. A common toy that is also a heat engine is a drinking bird. Also the stirling engine is a heat engine. All of these familiar heat engines are powered by the expansion of heated gases. The general surroundings are the heat sink, providing relatively cool gases which, when heated, expand rapidly to drive the mechanical motion of the engine.

I can't find any errors in the post. Are you sure you're trying?

 

[temporalillusion]

The sphere. Motion is relative. Are you now claiming that when the balloon and fluid are not at the same speed, that the relative motion is not zero?

I'm not claiming anything, you calculated the force from drag twice, once "Moving sphere, still air" and once "Moving air, still sphere", I just asked "relative to what?".

You answered "The sphere."

So the first force "Moving sphere, still air" is calculated for a sphere that's moving relative to itself? alrightythen...

If I did claim that the relative motion is not zero, then I'd plug in a zero for velocity, and see what the formula puts out.

Have you figured out how an airplane generates lift yet?

You have been sold a half-baked idea that relative something to do with absolute motion and you need to specify that. It doesn't, and the argument is internally inconsistent. Now where did you get that from? Was it from a visitor from Planet Oil Barrel, perchance?

There's no such thing as absolute motion.

No idea what Planet Oil Barrel is, a Google search of it comes up with you being the only one to ever mention it.

 

[dogjones]

61 pages, and still no-one has actually told me how many roads a man must walk down.

Bloody hell.

 

[Llyricist]

61 pages, and still no-one has actually told me how many roads a man must walk down.

Bloody hell.

42

 

[humber]

I'm not claiming anything, you calculated the force from drag twice, once "Moving sphere, still air" and once "Moving air, still sphere", I just asked "relative to what?".

Believe it or not, they are not the same. Fact. See Feynman's Sprinkler and many other examples where things are not so symmetrical as was thought 400 years ago.

You answered "The sphere."

So the first force "Moving sphere, still air" is calculated for a sphere that's moving relative to itself? alrightythen...

If I did claim that the relative motion is not zero, then I'd plug in a zero for velocity, and see what the formula puts out.

Have you figured out how an airplane generates lift yet?



There's no such thing as absolute motion.

No idea what Planet Oil Barrel is, a Google search of it comes up with you being the only one to ever mention it.

Then too bad.

 

[humber]

I can't find any errors in the post. Are you sure you're trying?

I accept your apology.

 

[3point14]

<Snipped> My point is that one has to wonder why so many ostensibly bright people like yourself would bother to engage him if in fact there was nothing but nonsense behind all of his claims?

It's like watching a train wreck. You just can't take your eyes off it.

I think it's that it's so easy to prove (to my mind) the possibility of DDWFTTW with any number of simple thought experiments, the application of physics or perhaps even (and I realise that this is radical) an actual working cart, that we all live in hope that someone will finally find the right combination of words to make him understand.

Even getting him to acknowledge the possibility he might at some point in his life have been wrong would raise a cheer from the gallery.

 

[humber]

It's like watching a train wreck. You just can't take your eyes off it.

I think it's that it's so easy to prove (to my mind) the possibility of DDWFTTW with any number of simple thought experiments,

Oh, that is how it's done? Just relax, as you think up something that will convince you. Better hope that works.

the application of physics or perhaps even (and I realise that this is radical) an actual working cart, that we all live in hope that someone will finally find the right combination of words to make him understand.

Even getting him to acknowledge the possibility he might at some point in his life have been wrong would raise a cheer from the gallery.

Yet none of you can answer to the claims that support the cart, and the trial is garbage.

 

[ThinAirDesigns]

My point is that one has to wonder why so many ostensibly bright people like yourself would bother to engage him if in fact there was nothing but nonsense behind all of his claims?

One has to wonder why you still wonder when every time you ask that question it gets answered the same way.

JB

 

[3point14]

Oh, that is how it's done? Just relax, as you think up something that will convince you. Better hope that works.

Take a cart.

Put two long tracks along the same axis as the axles, one fore, one aft.

Put a sail at an end of each of those, one on each track, one on the left one on the right.

As the wind blows DDW with respect to the cart create enough friction between the sails and the cart such that the sails both push the cart and push themselves along the track.

When each sail reaches the end of the rail, turn it around.

Hey presto. There may be engineering problems that would make this approach impossible, but as this is a thought experiment I don't have to worry about them.

(I have a better one about a planet sized, Rama shaped world covered in water, but I haven't quite worked out the details yet.)


If it's possible to go downwind faster than the wind then it's possible to go directly downwind faster than the wind.





ETA: It's just occurred to me that the final part of this thought experiment is to loop the rails all the way around so the sail doesn't have to stop and change direction...

 

[A.T.]

So what?
It's all ballpark out-of-our-respective asses "data" anyway.
The concepts don't need no steenken' numbers!

I didn't ask you for numbers. I asked you to define your "concepts" in terms of known physical concepts (like forces, velocities). You ask people to define their terms, but cannot do so yourself. Saying things like "sail effect is when it acts as a sail" is not a definition, but rather self referencing nonsense.

 

[Jack by the hedge]

ETA: It's just occurred to me that the final part of this thought experiment is to loop the rails all the way around so the sail doesn't have to stop and change direction...

Yeah, there's a video animation very similar to that, but humber doesn't want to talk about it.

It's curious with all this digression into heat engines etc that humber has overlooked explaining why it is that he wrongly believes a neutrally buoyant balloon released when travelling faster than windspeed would slow to less than windspeed.

A suspicious individual might think he was trying to change the subject to avoid admitting he was wrong.

 

[temporalillusion]

Believe it or not, they are not the same. Fact. See Feynman's Sprinkler and many other examples where things are not so symmetrical as was thought 400 years ago.

Just because a specific system is not symmetrical does not mean all systems are asymmetrical for every possible change. In Feynman's sprinkler the change wasn't a simple "is this moving or is it stationary".

You'll have to be more detailed as to precisely why there's an asymmetry, why a region of air moving with respect to the sphere somehow behaves differently than the sphere moving with respect to the region of air.

Then too bad.

Too bad what?

Still not going to educate us on how an airplane generates lift?

 

[I Ratant]

I didn't ask you for numbers. I asked you to define your "concepts" in terms of known physical concepts (like forces, velocities). You ask people to define their terms, but cannot do so yourself. Saying things like "sail effect is when it acts as a sail" is not a definition, but rather self referencing nonsense.

.
And yet, you comprehend what is being discussed.