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

[humber]

In Nebraska, an east wind is blowing at 10 m/s, and a boy is standing still, flying a kite. In Kansas, it's dead calm, and a boy is riding a bicycle at 10 m/s, eastbound, with an identical kite tied to the seatpost. That kite is likewise flying. Both kites have the same length of string unfurled, and they're flying at the same altitude. At the same instant, both kite strings snap at the point where they are attached to the kites. The wind keeps blowing in Nebraska, and the bicycle keeps rolling in Kansas. There is no thermal activity, and there are no terrain features to deflect the wind in a vertical direction.
1) Which kite hits the ground first?
2) Which kite is the greater distance from its owner when it hits the ground?

In Nebraska:
(A) There is real wind in this case. The kite is tethered and had no motion w.r.t the ground. That means zero KE. When the string is cut, the kite moves immediately away from the kite handler. Its velocity will depend upon circumstance and design of the kite but will be directly proportional to time, and in the simplifying case linearly proportional .

In Kansas:
(B) In Kansas, the kite is in motion w.r.t the ground, because it is being dragged through the air in order to generate the "wind" that keeps it aloft. This means that it has KE, whether you agree or not.
Once the string is cut, the KE will continue to carry the kite in the direction of the cyclist (Who unlike the belt observer, would have the option to stop). After the KE has dissipated against friction of the air, a force retarding motion, the kite will fall to the ground. Its displacement will be some what East (the same direction as the cyclist) of the point where the string is cut, but the distance to the cyclist is indeterminate.
It is approximately, the absolute displacement is the cyclist, less a small amount proportional to the kites KE, and not directly proportional to time, and certainly not linearly so

Notes:
(C) There is the unjustified assumption that the cyclist's velocity will remain the same after the kite is released. This cannot be so for all possible wind equivalents, as they are all to some degree load dependent. This limitation applies to the treadmill belt, and the level of friction to that belt.

(D) The kite or other object, may be modified to make the difference even greater.

(E) This exposes the lack of KE in the treadmill model, and its obvious influence on that result, that is nor present in real wind.

(F) The real-wind observer is stationary and carries no KE (w.r.t the ground if you insist) but not for the real-wind tethered kite.

(G)For the cysclist and treadmill, both kite and observer have unavoidable KE, as there is motion w.r.t the ground.

(H) Motion of the released kite in Kansas, cannot be said to be predictable. It is not acceptable to wish away thermal effects and the essentially random motion of small scale aerodynamic effects. This also applies to the real wind but they will be small compared to the actual and overriding force of the wind itself.

(I) The level of work is also quite different. etc..etc...

 

[humber]

Don't fall for it Humber ... it's a trick question.

JB

You did.

 

[humber]

You are wrong as usual.

Back to simple denial.

 

[Subduction Zone]

humber the KE will not continue to carry the kite forward, its momentum will, they are two very different things. Both kites after the string is cut will see the same forces of acceleration so they will hit at the same time. The "real" wind will have the same variation in velocity that the "still" day will have. No day is perfectly still and no wind is uniform in its velocity.

 

[humber]

Ho-
Lee-
Carp.

I am amazed at those with the persistence/dedication/stubbornness? to continue to attempt to lead Humber towards reason.

Dave

OK. Next hitter.
"Ho-Lee-Carp." I say that is the best you can do, CNY_Dave.

 

[Tunny]

For the period before the balloon

You mean kite? You keep switching these, probably in an effort to inject still more confusion...

hits the ground, the distance will be greater in real wind.

Utterly, totally, ludicrously wrong. As usual.

the balloon [KITE!] in real wind will show a larger distance between Anubis or Jane than on the belt, because at no time is there motion that closes that gap, (i.e. 100% of motion is away from the real wind observer), where as on the treadmill, the KE carries that object towards that same observer, even if only briefly. Both are detectable.

No. Frame switching again. You just can't seem to get away from it. Listen carefully. There is NO RELATIVE MOVEMENT OF THE KITE TOWARD THE BELT OBSERVER. Not before the string is cut, not after, not briefly, not ever. It is relatively motionless while tethered, then it quickly recedes when the string breaks, to fall at exactly the same distance from the belt-borne kite-flyer as in the "real wind".

But of course the real balloon or kite will fly away and not hit the road.

Balloons and kites are quite different in this regard, so again I wonder why you conflate them, if not to mislead. In any case, the same object will behave exactly the same in either scenario, relative to the kite-flyer.

Out of curiosity, just what force do you posit that will keep an inert, untethered heavier-than-air object like a kite aloft indefinitely in a horizontal wind? You like to use the word "impossible" a lot -- do you not see how this, unlike DWFTTW, actually is impossible?

Tunny

 

[humber]

humber the KE will not continue to carry the kite forward, its momentum will, they are two very different things. Both kites after the string is cut will see the same forces of acceleration so they will hit at the same time. The "real" wind will have the same variation in velocity that the "still" day will have. No day is perfectly still and no wind is uniform in its velocity.

Yes SZ. I deliberately made that distinction. The KE powers the process, the velocity is indeterminate and conditional. The KE will be dissipated over a period of time, that will (probably) result in some displacement. That may even include oscillation. The potential for that displacement is present in one case, but not in real wind.

 

[humber]

You mean kite? You keep switching these, probably in an effort to inject still more confusion...

Utterly, totally, ludicrously wrong. As usual.

Put up, or shut up. Evidence,drawings. Not simple smug assertions.
There are both kite and balloon examples. The latter posted today. Given that lack of attention span, it should be easy for you.

No. Frame switching again. You just can't seem to get away from it. Listen carefully. There is NO RELATIVE MOVEMENT OF THE KITE TOWARD THE BELT OBSERVER. Not before the string is cut, not after, not briefly, not ever. It is relatively motionless while tethered, then it quickly recedes when the string breaks, to fall at exactly the same distance from the belt-borne kite-flyer as in the "real wind".

Save your capitals. There is motion of the kite or balloon towards the observer. From any frame. Period.
Newton says that things move in the same direction unless otherwise inhibited. The KE powers that process.
The result is the same for all frames. Next.

Balloons and kites are quite different in this regard, so again I wonder why you conflate them, if not to mislead.

There are two sets of drawings. The ideas are the same. I need only consider the case for the belt or wind and not cross-couple them.

In any case, the same object will behave exactly the same in either scenario, relative to the kite-flyer.

Unsupported assertion. Proof. Evidence. Drawings.

Out of curiosity, just what force do you posit that will keep an inert, untethered heavier-than-air object like a kite aloft indefinitely in a horizontal wind? You like to use the word "impossible" a lot -- do you not see how this, unlike DWFTTW, actually is impossible?

Lift. Tell me it can't be done. If you should succeed, I will find another object. The balloons re met balloons and lighter than air. I weighted them to be less than bouyant. But as I said, there are countless other objects.

Tunny

 

[John Freestone]

It is one of those things that "ordinary people" might expect, that if we race along the ground pulling something (airborne or otherwise), then let go, it will have momentum that will carry it forward in such a manner as differentiates it from the other scenario - standing still with something (air) pulling on an object, which we then let go of.

Ordinary people (and some extraordinarily vocal ones) imagine that a body moving with respect to the earth has momentum, absolute momentum, and not one that is stationary w.r.t. the earth. As we have discussed for months now, velocity is relative to a position, the Earth has no special place, and hence humber's latest (recycled) argument still fails.

If one doubts this, he only has to imagine that the "killoon" is extremely massive, has no area to be dragged by the air, yet is held up by a mysterious force while pulled (in the way a kite is held up by the air). Then, when the Earth-motion-in still air one is let loose, its enormous momentum will cause it to continue to move, following the cyclist or whatever, be accelerated due to gravity, and, since it is not dragged by the air, will land right at the back wheel, assuming it was held vertically above the back wheel. Both cyclist and object will continue to travel together. The Earth-stationary one will simply fall, a dead weight, landing vertically underneath where it was held.

I'm a fairly ordinary person, and humber nearly had me with that one! Seriously. I know, after all this time, I still consider what he's saying.

 

[ThinAirDesigns]

In Nebraska:

<snip>

...

All those words and yet not a single attempt to answer the 2 simple questions:

1) Which kite hits the ground first?
2) Which kite is the greater distance from its owner when it hits the ground?

JB

 

[Tunny]

There is motion of the kite or balloon towards the observer. From any frame. Period.
Newton says that things move in the same direction unless otherwise inhibited. The KE powers that process.
The result is the same for all frames. Next.

Newton would find your assertion that there is motion toward the observer in all frames quite fascinating, I suspect. You don't know what a frame is, and apparently never will, because it would be impossible to utter such an inane statement if you did.

Lift. Tell me it can't be done.

Heavens no, you've got our rapt attention now. Please expound for us on how you can keep an inert, untethered, heavier-than-air object aloft indefinitely in a horizontal wind.

Tunny

 

[mender]

Recursive prophet, do you still think humber is carrying on a many-leveled parody, or is his concept of physics the parody on many levels?

"Tell me it can't be done. If you should succeed, I will find another object."

Humber, your game play won't allow you to actually learn from your mistakes. You need to find someone that you trust and show them your diagrams. Hopefully they will be able to change your mind. I obviously can't.

 

[humb]

In Nebraska, an east wind is blowing at 10 m/s, and a boy is standing still, flying a kite. In Kansas, it's dead calm, and a boy is riding a bicycle at 10 m/s, eastbound, with an identical kite tied to the seatpost. That kite is likewise flying. Both kites have the same length of string unfurled, and they're flying at the same altitude. At the same instant, both kite strings snap at the point where they are attached to the kites. The wind keeps blowing in Nebraska, and the bicycle keeps rolling in Kansas. There is no thermal activity, and there are no terrain features to deflect the wind in a vertical direction.
1) Which kite hits the ground first?
2) Which kite is the greater distance from its owner when it hits the ground?

Too many assumptions. The answer is interdeterminate, yet I can make it be whatever I wish.
a) You are assuming that the kites are identical. What if they are not?
b) The cyclist may stop for lunch, or may start drafting behind a truck.
c) A bird may pick up one, or the other, kite.
d) Either kite may be struck by lightning.
e) One of those "boys" may in fact be a girl.
f) Once the strings break, the Nebraskan may get on his motorcycle and in a couple of minutes he will be around the track, or more!
g) One of the kites may actually be a treadmill. HAH! You won't fool me that easily! A treadmill is not a kite!
h) The altitudes may be different in the two states, and thus the air density will whether only some by.
i) Any fool knows that the Nebraska kite will never reach the ground, it will continue to be blown along like a feather, while the Kansas kite will plummet like a hammer dropped on the moon. It is the same as a bullet fired from a gun, compared to one dropped onto a treadmill. That is why the sky is now littered with kites, and the sunlight no longer reaches the ground, and we all dwell in the darkness like moles, or the chiropterids that I am still trying to evict from the church. I remember in my youth when we could still see the sunshine, and I long for those days. And we didn't have to crawl on our bellies back then, either, because there were no bullets perpetually whizzing around at chest height. There is supposedly a government program to teach butterflies to eat the kites, but I haven't seen any results thus far.

 

[Michael C]

These balloons are of the type cited in the the meteorological balloon book. That is confirmed and accepted as being the nature of those balloons.
On the treadmill, lack of air flow when released, allows the balloon to fall. In real wind it remains aloft. Crystal clear.

A meteorological balloon doesn't stay airborne because of the wind, it stays airborne because it's lighter than the air. If it's heavier than the air, it descends, wind or no wind. The balloon doesn't care what the speed of the air over the ground is: it is only affected by the air around it. If you've ever ridden in a balloon, you'll have noticed that you don't feel any wind. It doesn't matter how much wind is measured at ground level: in the balloon no wind is felt because the balloon moves with the air.

(1) The real balloon does not touch the ground.

That's news: one balloon is real and one isn't? Since we're trying to make equivalent scenarios here, the two balloons are identical. You said that they are "not quite buoyant". They are therefore slightly heavier than the air, and will both slowly descend. They will both reach the horizontal speed of the air at the same time.

You could test this easily with a helium-filled balloon from a novelty shop. Hang just enough weight on it so that it slowly descends to the floor when you release it indoors. Now go out on a day without wind, run a few metres while pulling it along, then let go. Note how long it takes to descend to the ground. When there's a day with a wind speed about the same as your running speed, hold it in the wind at the same height as when you were running with it, then let go. If you find that the balloon takes significantly longer to reach the ground in the second case, please alert NASA, the JREF and indeed the whole scientific community: you are capable of defying the laws of physics.

 

[ThinAirDesigns]

Too many assumptions. The answer is interdeterminate, yet I can make it be whatever I wish.
a) You are assuming that the kites are identical. What if they are not?
b) The cyclist may stop for lunch, or may start drafting behind a truck.
c) A bird may pick up one, or the other, kite.
d) Either kite may be struck by lightning.
e) One of those "boys" may in fact be a girl.
f) Once the strings break, the Nebraskan may get on his motorcycle and in a couple of minutes he will be around the track, or more!
g) One of the kites may actually be a treadmill. HAH! You won't fool me that easily! A treadmill is not a kite!
h) The altitudes may be different in the two states, and thus the air density will whether only some by.
i) Any fool knows that the Nebraska kite will never reach the ground, it will continue to be blown along like a feather, while the Kansas kite will plummet like a hammer dropped on the moon. It is the same as a bullet fired from a gun, compared to one dropped onto a treadmill. That is why the sky is now littered with kites, and the sunlight no longer reaches the ground, and we all dwell in the darkness like moles, or the chiropterids that I am still trying to evict from the church. I remember in my youth when we could still see the sunshine, and I long for those days. And we didn't have to crawl on our bellies back then, either, because there were no bullets perpetually whizzing around at chest height. There is supposedly a government program to teach butterflies to eat the kites, but I haven't seen any results thus far.

Classic. Humb and Humber -- double your pleasure, double your fun.

JB

 

[Furcifer]

There is nothing wrong with my education, so there is nothing to teach.

And there it is.

Education means knowing there is so much more to teach. Wisdom is realizing this.

 

[semper]

Sure, but it would do so whether there was "Real" wind or not, and, in the absence of any type of vertical current, "Gliding" necessarily involves the loss of height. Humber seems to think a kite magically "Gains power" from the wind and maintains altitude, even though it is at wind speed and therefore has no relative airflow.

Whilst agreeing that Humber is wrong, I'm not sure I agree entirely with the above statement "in the absence of any type of vertical current, "Gliding" necessarily involves the loss of height". I suppose it depends on your definition of 'gliding' but one of the interesting things to have become apparent lately in the world of gliding is that it is perfectly feasible to stay aloft using only horizontal gradient difference (see 'dynamic soaring'). In fact it is the same sort of energy difference extraction as this whole topic is really about. Please don't tell Humber, I'd hate to introduce yet another concept for him to be completely unable to comprehend using his flawed thinking methods.

 

[GregLondon]

Wow, the number of posts in a day is amazing.

I have been involved in the design of cockpit equipment,

Cool, I worked on some cockpit avionics for the F22, C130, and CH46. Moving map displays, waypoints and navigation stuff, artificial horizon, compass bearing, heads up display, targeting info. Everything you can put on a digital display on LCD screens. stuff like that.

What did you work on?

 

[GregLondon]

The Newton second (N s) is perfectly adequate name for a unit of momentum

Thanks. I'll put that into the next rewrite.

 

[semper]

Hi Humber, first let me apologize for all the nasty things you have done to physics. The thing is, I am coming along in trying to understand "real" wind, but I have a problem. There is no wind, and I have a sailboat. I really need to cross the river and it is too dangerous to swim because there is a strong current. Some people have told me that its ok, I will still be able to sail across. But Humber, can I trust this "artificial" current created wind? Please Humber, please let me know how to recognize the real wind. If I use the artificial stuff, will the other side of the river become artificial too?