Split Thread The validity of classical physics (split from: DWFTTW)

[semper]

Humber, can you please re-state your laws of motion. It is getting more difficult to determine your analysis of any given problem. You seem to be trying to say something, but it gets confusing with all the various analogies and thought experiments going on. Could you just start over and lay down you basic premises.

 

[John Freestone]

The balancing cart is a simple fact, Myriad. I can't force you to accept that.

"It is a simple fact" - now what was it you just said about spork saying "clearly"? The problem is that it isn't a "simple fact", because you haven't ever expressed it clearly. If we take "balancing" to mean that the cart's particular mechanical device does not keep it on a treadmill, but any little cart on wheels (or sphere, such as an orange approximates to) would do the same, then say so, and we can do the serious experimental part to see if you're right. (Hint: you're not, and we already did.)

I presume though, that you agree that a kite on a string can remain aloft in wind?

Yes...?

The kite is tethered, so there will be a force on the string, equal to that generated by the wind upon the kite, so the kite will be stationary w.r.t the ground.

Yes.......?

If that force, that reaction, were replaced with another, then the kite would be none the wiser, and continue to do as it was.

Yes.............?

If that force were provided by a drogue; itself free and powered by the wind, then in principle, the kite would remain aloft, but stationary.

You know, I'm not sure. I think it could, yes, if the string were taken from the kite in the usual direction (forward, just to be clear), wrapped round a stationary pulley, so that the drogue's drag force is transfered through the string to the front of the kite, I think that might just work. I wonder what the expert aero people think.

I wasn't too clear before about bricks tied to kite strings. "Clearly", that works if the brick holds the kite back as well as down. You just can't fly a kite by attaching a counterweight to it that isn't heavy enough to keep it effectively tied to the ground (or anything moving slowly enough w.r.t. the wind) that the kite sail can gain lift. If the brick is too light and gets dragged across the ground too fast, the kite won't get enough lift.

That is possible in wind,

I will just assume you mean, "by reversing the drag of the drogue with some sort of suitable pulley device, etc.", and didn't bother to state the obvious. "Clearly" you couldn't possibly mean that tying a drogue parachute to a kite will provide the same resistance to it being blown downwind that its string would, without such reversal. You would "clearly" understand that a parachute would be blown to the rear of the kite if "free"... and the whole thing would just blow away and fall down in a mess of 'canvas' and string (my god, how old am I, 'canvas'?).

but not at all on the treadmill.

Well here it is once again just a matter of deciding what the equivalence is - in this case it would be to fix a pulley to the moving surface of the belt. If it works in 'real wind' then it will work in 'artificial treadmill wind', except that to prove it would probably take a lot longer treadmill than is usual - maybe one of those moving walkways you mentioned could be used - there are so many experiments you could do there if they allowed you to... ETA:...or just have someone drive you about on a still day doing them on the back of a flat-bed truck or something. Clearly, you might need some help setting it up. Clearly, you shouldn't be the one driving at the same time.

Change that balance of forces and the kite will move. That is the connection to the basket of a balloon, and the idea of load matching, amongst others.

I don't understand that, but it sounds like more of your magic kite flying.

It is not difficult to fins more exemptions.

Odd that you haven't found one yet then.

That may be possible, but I don't need to consider that. The treadmill cannot behave like the wind in many significant ways.
Drop a leaf in wind, and it blows away, do so on the treadmill, and it falls to the belt. It flutters to the ground, whereas in the wind, it may not, and even gain lift. You can Google that, to see how much there is to that topic alone.

Yes, yes, the turbulence is going the wrong way, I know.

To equate the belt and wind, is simplistice.

Fixed that.

...an over-extended metaphor of relative motion, but even that is brought to ground, by the reliance on the
'absolute" belt. It contradicts itself, let alone reason.

Relative motion is all we can know. The belt is a relative belt. If you bothered to think about my earlier arguments about the motion of the Earth's surface and so on, you would realise that. Turn your "absolute" belt round and its surface can be going a different speed. Clearly. That's a simple fact.

 

[jjcote]

(This should have occurred to me earlier.)

To equate the belt and wind, is simplistic.

Congratulations on finally seeing the light, humber. Yes, it's a simple fact that they are equal. I'm glad that you finally acknowledge that, and that you further went on to admit that the rest of your misconceptions were primarily due to a simple arithmetic error. Now that you see how relative motion works, you'll find that many physics problem can be analyzed much more readily, and the rest of the discrepancies between the humberverse and the real world will quickly be reconciled.

My work is done here. Adios.

 

[Michael C]

Those are great quotes, Michael. Thanks. I just want to 'relativize' that last bit. These words all depend on our definitions, and there are indeed heavier than air balloons that fly, if you define a ballloon in a certain way. We can fly by using lift - which is to overcome weight - so we can use a bit of both technologies together.

There are planes that are partially filled with helium to reduce their weight significantly, while still being heavier than air. They then gain lift in one of the conventional ways to oppose the remaining weight. Is that a balloon or a plane? It's not a lighter-than-air machine, certainly, but often they have large volumes of lighter-than-air gas, making them rather fat and balloon-like.

That would be a hybrid airship. A balloon aircraft, by definition, is lighter than air and has no engine. Maybe Humpty Dumpty or Humber would invent other definitions, but we'd do better to stick with the accepted one.

 

[Michael C]

Congratulations on finally seeing the light, humber. Yes, it's a simple fact that they are equal.

Careful: Humber said "simplistic", not "simple".

 

[Furcifer]

A change in balance, due to gravity. Next.

No, a change in the direction of applied force. Just like the wind is notorious for.

Perhaps the leaf would get blown from the road, to the roadside. If the belt is the road, where is the roadside?
You completely missed the point, of course.

You have no point, remember? You have to present a point for anyone to miss it.

One for me.

One giant leap for humberkind

That's why you never see aircraft anywhere near roadworks.

You've never seen an aircraft on roadworks?

This 3 year old knows better than you.

 

[John Freestone]

Still on with the 'real wind' codswallop? Still under the impression that to define something means to say "Maybe that it's independent?" or "Like when it's..."? Still think that's a way to usher in an advanced view of mechanics to overturn 350 years of us doing it the wrong way? We should abandon specific definition of things and say real wind is like when you're outside, man, and not like artificially produced, y'know?

It's a still day at the North Pole. It's a still day at the equator. I wonder if one of those is a real still day.

 

[humber]

UOT

(This should have occurred to me earlier.)

It would have, had I posted it

Congratulations on finally seeing the light, humber. Yes, it's a simple fact that they are equal.
I'm glad that you finally acknowledge that, and that you further went on to admit that the rest of your misconceptions were primarily due to a simple arithmetic error. Now that you see how relative motion works, you'll find that many physics problem can be analyzed much more readily, and the rest of the discrepancies between the humberverse and the real world will quickly be reconciled
My work is done here. Adios.

You were done log ago.

 

[Clive]

Could be that it is independent, Clive.
Like the artificial wind of a wind tunnel, that is not found at the end of the garden path, Clive.

Can't really accept the relevance of anything being independent given the extremely low s/n ratio being detected in the input stream. Understanding the various symmetries is the first step towards recognition of the simplifying assumptions that can be made, and then seeing the equivalence should be easy. Not sure why you mention the wind tunnel now as it was always acceptably "real" for you previously? The treadmill wind can be trivially transformed even into what you'll find at the end of your garden path if you select the correct initial conditions, and if that seems too hard then perhaps consult the pixies that I'm sure you keep down there.

 

[John Freestone]

That would be a hybrid airship. A balloon aircraft, by definition, is lighter than air and has no engine. Maybe Humpty Dumpty or Humber would invent other definitions, but we'd do better to stick with the accepted one.

Thanks, and for the purposes of this discussion, I'm happy to agree and call it a hybrid airship. But really, IMHO, there is little wrong with using different names for things, principles and processes, as long as they are described clearly enough to be unambigous. I think we have to strike some kind of balance between standardisation and linguistic fascism. They say that you can fly a garage door if you give it enough thrust, but we can argue all day about whether it is a "fixed-wing aircraft" or a "flying garage door".

Anyway, it hardly matters compared with trying to clarify that normally "hot-air balloons" and "helium balloons" don't fly by gaining lift, nor "planes" fly by being lighter than air. It's amazing we are doing.

New propositions like "real wind", OTOH - well, we can't do much with them at all until we have a definition.

 

[John Freestone]

Don't know. Are there winds that are not real?

Don't know. Are there? Don't think so. Your concept. You say.

 

[John Freestone]

Now that there has been a begrudging admission that momentum may power a cart to windspeed, do you think that may be part of the reason why meteorological balloons can travel close to the wind?

No. It's the drag of the wind that does that. The windspeed will change velocity somewhat, and the balloon, via that drag upon it, will track the windspeed, slowing to its new speed, speeding up again to match it (as near as makes no odds and exactly in the steady state - admittedly a theoretical proposition since we live in a chaotic world). It's momentum will act against it acheiving windspeed, against its acceleration by that drag force, but it won't have significant amounts of it because it is so light.

The book on that topic, posted in this thread, emphasizes the role that acceleration plays in that achievement.

We've been through all this. You didn't understand it then, and you won't understand it now. It is manufactured at almost a standstill. When it's at windspeed, it has to have been accelerated to change its velocity from near-0 to near-windspeed, see, which it is by the air dragging at it once it's launched. I haven't read the book, but I think that's probably something like it. Maybe you could ask a bunch of kids in infant school and see if they have any ideas.

It's interesting that you jumped at that momentum cart principle and didn't ask "...so does anyone think that maybe that's how spork's cart does it after all?". That was once your theory, wasn't it. Have you, er, changed your, er... no, forget it, that's impossible!

ETA: And, btw, it wasn't a grudging admission, it was someone expanding our reliable knowledge of the physical world. You should join in sometime.

 

[humber]

No, a change in the direction of applied force. Just like the wind is notorious for.

Not so notoriously that its boundary layer runs opposite to the wind.

You have no point, remember?

I will be blunt next time.

You have to present a point for anyone to miss it.

Not just anyone.

One giant leap for humberkind

Something else that failed to fly.

You've never seen an aircraft on roadworks?
[qimg]http://www.drtoy.com/images/items/fisher_price_2002_1_c.jpg[/qimg]
This 3 year old knows better than you.

Don't try to be clever. Common usage has set that to '5 year old'.

Now, look what you've gone and done. right there.
Like the treadmill, that may not be what you think it is.

 

[humber]

That would be a hybrid airship. A balloon aircraft, by definition, is lighter than air and has no engine. Maybe Humpty Dumpty or Humber would invent other definitions, but we'd do better to stick with the accepted one.

I call them 'anti-gravity' machines, Michael_C.
Air is denser than the craft, so the gravitational force upon the equivalent volume of surrounding air, is greater than on the airship, and so displaces it.

 

[John Freestone]

Now you're catching on!

1 out of 4 ain't bad humber.

I make it -4 out of 4, but then I'm using a different scoring system.

One for me.

Gratefully accepted.

Sorry to burst your kite, but it's something like -virtuallyEverything.

 

[John Freestone]

Could be that it is independent, Clive.
Like the artificial wind of a wind tunnel, that is not found at the end of the garden path, Clive.

Curiouser and curiouser. So aerodynamic bodies like kites, balloons, planes, etc., work properly outside, but not on a treadmill, because of the imaginary wind, the boundarly layer going the wrong way, and the lack of turbulence, but they don't even work in a windtunnel?

Yeah, the principles of the humberverse are getting too random now. It was fun when they had a kind of ridiculous internal logic, but now we can't even test aerodynamics in windtunnels. It's like watching a bad sci-fi. You can enjoy all the rockets making noise in a vacuum and stuff, but if the main character suddenly changes his name, rank and favourite flavour of icecream for no apparent reason, or the aliens just die without explanation, it's a real letdown. I might switch over.

 

[John Freestone]

UOT How does humber manage to keep getting bits of the word "Quote" in the title field?

(Endlessly fascinated by the natural world.)

 

[humber]

"It is a simple fact" - now what was it you just said about spork saying "clearly"?

Yes I do.
The balancing is not so simple, but it is simply a fact.

The problem is that it isn't a "simple fact", because you haven't ever expressed it clearly.

Amply and fully supported.

I wonder what the expert aero people think.

All out of town at the moment.
You seem to accept that metaphorical pulleys can drive a yo-yo, but this simple possibility, escapes you. There are many possibilities for 'reversing' the force' but you know it can be done, because of the Ventomobile, that runs against the wind.
So now you can fully agree.

I wasn't too clear before about bricks tied to kite strings. "Clearly", that works if the brick holds the kite back as well as down. You just can't fly a kite by attaching a counterweight to it that isn't heavy enough to keep it effectively tied to the ground (or anything moving slowly enough w.r.t. the wind) that the kite sail can gain lift. If the brick is too light and gets dragged across the ground too fast, the kite won't get enough lift.

If provides a load, and keeps the kite stable. That allows more power to be transferred. See MPT.
Note also the difference between static and dynamic force.

I will just assume you mean, "by reversing the drag of the drogue with some sort of suitable pulley device, etc.", and didn't bother to state the obvious.
"Clearly" you couldn't possibly mean that tying a drogue parachute to a kite will provide the same resistance to it being blown downwind that its string would, without such reversal. You would "clearly" understand that a parachute would be blown to the rear of the kite if "free"... and the whole thing would just blow away and fall down in a mess of 'canvas' and string (my god, how old am I, 'canvas'?).

There is no pulley, and the forces need not be equal. None of those arrangements you describe can work on the treadmill. Nothing can fly without a string on the treadmill. That is not like any wind tunnel, or real wind.

Take a familiar example. Run with a kite against the wind. It flies and you feel the wind. On the treadmill, how do you run against the wind?
At best, being on the belt is like running in still air, but only if attached to the belt with sufficient adhesion to support the necessary force. That cannot drive a windcart in the same manner as the real wind.
Wind speed is stand still, in still air.

Well here it is once again just a matter of deciding what the equivalence is - in this case it would be to fix a pulley to the moving surface of the belt. If it works in 'real wind' then it will work in 'artificial treadmill wind', except that to prove it would probably take a lot longer treadmill than is usual - maybe one of those moving walkways you mentioned could be used - there are so many experiments you could do there if they allowed you to... ETA:...or just have someone drive you about on a still day doing them on the back of a flat-bed truck or something. Clearly, you might need some help setting it up. Clearly, you shouldn't be the one driving at the same time.

'Given an infinite treadmill' and 'boundary conditions' are excuses.
Your example may hold if there were to be a moving flatbed truck with each wind cart. Video #7 shows there are no pixies behind the curtains, but also no trucks.

I don't understand that, but it sounds like more of your magic kite flying.

Not my fault.

Odd that you haven't found one yet then.

Gliders. In fact anything that can be though of as flying. Only devices that balance, can stay on the belt.

Relative motion is all we can know.

So why make a fuss about it.

The belt is a relative belt. If you bothered to think about my earlier arguments about the motion of the Earth's surface and so on, you would realise that. Turn your "absolute" belt round and its surface can be going a different speed. Clearly. That's a simple fact.

Not a matter of bothering. Turn the treadmill around in the room. No difference. Yes I know, the ground; the frame that dare not speak its name.

No. It's the drag of the wind that does that. The windspeed will change velocity somewhat, and the balloon, via that drag upon it, will track the windspeed, slowing to its new speed, speeding up again to match it (as near as makes no odds and exactly in the steady state - admittedly a theoretical proposition since we live in a chaotic world). It's momentum will act against it acheiving windspeed, against its acceleration by that drag force, but it won't have significant amounts of it because it is so light.

So you say. The formula not. I imagine you think your car is powered by friction to the road.
It makes sense. You stop when you get a puncture, and they automatically refresh themselves by driving you to fill the tank.

We've been through all this. You didn't understand it then, and you won't understand it now. It is manufactured at almost a standstill. When it's at windspeed, it has to have been accelerated to change its velocity from near-0 to near-windspeed, see, which it is by the air dragging at it once it's launched. I haven't read the book, but I think that's probably something like it. Maybe you could ask a bunch of kids in infant school and see if they have any ideas.

KE is the result of acceleration. It can be later re-deplayed. It's like a hamster. Store when the force is available.

It's interesting that you jumped at that momentum cart principle and didn't ask "...so does anyone think that maybe that's how spork's cart does it after all?". That was once your theory, wasn't it. Have you, er, changed your, er... no, forget it, that's impossible!

No, read again.

ETA: And, btw, it wasn't a grudging admission, it was someone expanding our reliable knowledge of the physical world. You should join in sometime.

Perhaps you are right. Let's make that 'an attempt to warm-over my idea, so that it can be used to tell me why I was wrong in the first place.'

 

[GregLondon]

No, it was your stubbornness to even accept the idea. You do not even have a clue.

Humber, its very simple, point to a law of physical motion that says the maximum power you can transfer from one object to another is only 50%, that there is a physical equivalent to "electrical load", or just confess that you're flat out lying.

There is no such law. Therefore you're lying.

Oh, remember this little gem?

It's fundamental. When you store energy in that pendulum you mentioned, the losses are also very low. Small bearing friction. But, if the energy transferred to it from a mechanically 'real' source is 100J, then 200J must come from the source. 50% is lost in the source as perhaps heat. When the source and load are both real, i.e. dissipative, then 50% goes in the load and 50% is lost in the load when maximum power transfer occurs. A law of nature.

So, after getting nailed for the total farce that your "Maximum Power Theorem" is, you came back with this little gem as your smoke screen. That there are "real" sources of energy and "not real" sources of energy. And if it's "real", then you will lose 50% of your energy, because of some law of nature.

Which law, you haven't said. Because none such nonsense exists.

You're lying to cover your lies, humber.

And the real kicker? None of this has anything to do with the cart, the treadmill, or anything else. You're blowing smoke, humber. You don't know what you're talking about. You're lying.

This would be exactly the sort of thing I would expect the James Randi forum to not tolerate. Someone hiding behind a pseudonym, talking pseudoscience and technical mumbo jumbo, all of it wrong, to pull off some sort of con. Even if it's nothing more than a con to make yourself feel superior, to troll, whatever, it's still a con.

If you were charging money for this garbage, you'd deserve to be shut down in a heartbeat. For all I know, you're just practicing your con lines here for free so you can charge money in the real world.

 

[Michael C]

Thanks, and for the purposes of this discussion, I'm happy to agree and call it a hybrid airship. But really, IMHO, there is little wrong with using different names for things, principles and processes, as long as they are described clearly enough to be unambigous. I think we have to strike some kind of balance between standardisation and linguistic fascism. They say that you can fly a garage door if you give it enough thrust, but we can argue all day about whether it is a "fixed-wing aircraft" or a "flying garage door".

It would be both. But we couldn't call it a balloon