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

[mender]

I do actually. Raced a few month ago. Lap time 2 minutes. Hurrah for humber! Well no. The lap record is 1:18.
Taking a one second off two minutes, is brown underpants time, yet someone can take off 42 seconds. Unbelievable.

So, I just don't care what you believe, Spork

That must have been really confusing, humber, to have someone in the same race, going much faster than you, yet every second lap reappearing beside you. But the important point of course is were you ahead of the other rider when you both crossed the finish line?

Seriously though, it's good to get out on the track once in a while and learn more about the dynamics involved. Being the fastest is a lot harder than most people think, as it seems you've discovered!

 

[humber]

That must have been really confusing, humber, to have someone in the same race, going much faster than you, yet every second lap reappearing beside you. But the important point of course is were you ahead of the other rider when you both crossed the finish line?

Seriously though, it's good to get out on the track once in a while and learn more about the dynamics involved. Being the fastest is a lot harder than most people think, as it seems you've discovered!

1:18 was a timed lap, not a race. That time is probably not possible due to traffic. I did a lot of off road, so I was already aware of the potential, but that difference boggles the mind.

 

[humber]

A simple fact? No, more like a miracle. Could you show us a kite that can fly without string?

I wonder what worlds you all live in. I have lost kites in the manner described, but I don't think I have flown one since aged 8, so perhaps the wind has changed since then. ( I wonder how it is that it that everything can be said to reach windspeed except free kites.)

I also

The balloon is weighted to be not quite buoyant. Anubis is bored and has sent one of his many concubines to monitor the test.
On the treadmill, the balloon moves somewhat to the left, while Jane moves as shown. 'B' is the approximated motion due to the KE of the balloon and mass, eventually falling to the ground.

In the wind, the balloon is carried away to flight. Meteorological balloons carry instrument packs this way, so they will perform in this manner.

 

[mender]

Null point. Way too many new variables and unnecessary complication. Keep it simple.

No, humber, no new variables at all. Simply an extension of your scenario with the "observers" placed so that the only visible phenomena is that part that you claim is different in your original diagrams. In fact, this eliminates Anubis and the other distractions, uncomplicating the issue. In its simplest form, will your thought experiment and claim be supported?

The quotable humber:
If actually moving with the belt, (motion w.r.t the ground) the cart cannot move w.r.t the belt, so as to be seen making real displacement along that belt. That is impossible for any vehicle without energy storage, that is driven by the wheels.

So, Mender, what do you say?

Is the "real" displacement wrt the belt or the ground? I can't say until I know which. Another question, is the cart said to be storing energy or using it in order to achieve that displacement?

So humber, it appears that you have some reading to do about what the kite really does when released in a "real wind". The others on here have spared me the trouble of finding references and also replying to your comments on my kites above the clouds post.

As I said, at this point I feel there is very little I can do to help you to understand. You've made some bold statements that conflict with NASA's findings. Your ideas about what a "real wind" is capable of is in the magic realm to me. Your thought experiments aren't borne out by real world observations and measurements.

 

[mender]

Thank you, humber, for the new bunny/balloon diagrams. This confirms that you are not understanding what you see. I'd like to assure you that the bunnies' observations are identical but you seem to like splitting hares.

Perhaps it's time for you to go fly a kite - this time watch what happens when you release the string.

 

[humber]

No. Once again, it is you who has failed to differentiate between a hypothetical, a conditional (if....) and a statement of belief or fact, and assumes that the logic pertaining to it has been assumed to be true by the one posing it.

If hypothetical, who does the parsing. You would then need to show that only a binary outcome is possible. Being conditional, does not change that.
My answer, is the answer.

In fact, I was about to add that I do not like or agree generally with argument that is based on appeals to authority, or the number of people who believe something, and you fail to understand that I can dislike that as a line of argument, yet also pose it (not that I did) as a thought experiment.

As contradicted by your reference to polls etc.
The very question is based on the assumption of majority rule.

Your argument above is the same kind as if I had said, "Humber, if a doctor gave you the diagnosis of a narcisistic personality disorder, would you believe him?" and you had listed all the stupid assumptions I had made about personality disorders, the authority I invest in doctors, etc., etc.

Why would I? There is no unique solution to a recursive problem of that nature.

It seems that your imagination, the ability to think things that may or may not be true, is as limited in the social realm as it is in the scientific.

Caught you with your hand in the cookie jar with "ordinary people" though.

 

[Furcifer]

Now, please tell me how the cart can stay on the belt, in any other state than "windspeed". Good luck.

I'm not sure what you point is? Inside the cart on has to fight inertia on the belt. Outiside the wind must be great enough to overcome inertia as well.

Tell me how it goes faster than the treadmill on the treadmill? Good Luck.

Calculus is not for you then.
Did it hurt so much that you need to impute it to others?

No calculus was ok. Special Functions, I wouldn't wish on anyone.

You controlled but some of the variables. Is that why you think wind and treadmill are alike?
You have just explained why bicycles have gears, and how it is possible to gain more power if the engine is better matched to the load.
Perhaps 'maximum power theorem'?

Well you get gearing, that's all I needed.

You argue nonsense because you can't explain the principles involved. Your hand waving.

Why does the cart move faster than the belt on the belt but not in the wind?

 

[Michael C]

Can't you guys instead show the error in my posts and explain the difference between a towed paraglider and a kite?

While they're being towed, they both work the same way. What isn't the same is what happens when you cut the string, since a kite is not normally built to remain a stable position in the air without being tethered. When the string is cut, the glider will do what it's built for: gliding. The kite will first move upwards and away from the person flying it, since the force coming from the string was downwards and towards the kite flyer. This won't last long, though: the angle of the kite will change so that no more lift is produced, so the kite will quickly lose the vertical velocity component. Since it's pretty light, it will also quickly reach the horizontal speed of the wind. It will now drift down through the air, usually erratically since it is constantly changing position and therefore causing varying amounts and directions of drag.

 

[humber]

Humber, cant you see the problem in your writing?
Did you mean kite when you wrote balloon? I assume you did.
Yes, correct.

How is it possibly to draw this conclusion? Did Anabis leave the belt or what?

Yes, sorry I may transposed kite and balloon, but it makes no difference to the point.
Both kite and Anubis are moving to the left at the point of release. (The kite is dragged through the air by being attached by a string to Anubis)
So immediately after release of the kite, Anubis continues to move to the left with the belt, and the kite to the left by its KE.
When released, the kite will slow, but Anubis not, so the gap between will increase for that short period of deceleration of the kite.
After the kite hits the ground, the displacement is constant.
That is patently clear.

What you say are true but your conclusion above is definitely wrong. Anabis moves faster relative to the air than the kite but in the same direction. The distance between them is thus getting larger

Over the same time period, the gap will be bigger in the real wind because there is no motion of the kite towards the kite-handler after release. Assuming equal speeds for the kites, the real world will show a larger gap.
Additionally, the kite will not crash to the ground because there is air flow to support airborne motion, but not on the belt. Two differences.
That too patently clear.

Humber, here is a serious comment.
An observer on a belt and on the ground besides the belt can see the same thing relative to something they have in common and calculate the same velocities relative to something they have in common. This is not was this is about.

Yes, but that has been ignored until now.
I say that it is the point. Equivalency guarantees that all outcomes are the same. Not only must they be consistent within the treadmill and real worlds, but also between those worlds.

This is what the observer sees relative to them self.

Relative to itself is a redundant idea. True of everything.

Anabis flying his kite in a breeze is going to see the exact same thing as when he fly his kite from a belt if he compare everything relative to him.

No. The gap will be different. The treadmill wind is dependent upon the kite being held by Anubis. Real wind can independently drive the kite after release.
On the treadmill, without being dragged through the wind by the string to Anubis, there is no wind being generated. A simple fact.
It cannot be maintained that the kite is then at windspeed, because it crashes to the belt. Could not be more different, Fredriks.

 

[humber]

No, humber, no new variables at all. Simply an extension of your scenario with the "observers" placed so that the only visible phenomena is that part that you claim is different in your original diagrams. In fact, this eliminates Anubis and the other distractions, uncomplicating the issue. In its simplest form, will your thought experiment and claim be supported?



Is the "real" displacement wrt the belt or the ground? I can't say until I know which. Another question, is the cart said to be storing energy or using it in order to achieve that displacement?

So humber, it appears that you have some reading to do about what the kite really does when released in a "real wind". The others on here have spared me the trouble of finding references and also replying to your comments on my kites above the clouds post.

As I said, at this point I feel there is very little I can do to help you to understand. You've made some bold statements that conflict with NASA's findings. Your ideas about what a "real wind" is capable of is in the magic realm to me. Your thought experiments aren't borne out by real world observations and measurements.

If the first remark is true, then my scenario is also good. NASA's findings have nothing to do with this. I can make the kite a paprer bag.
There is nothing wrong with my education, so there is nothing to teach. The treadmill is flawed and that is a fact.
I have added more details again and gain, and now there is a balloon example. I will not address anything else.

 

[Michael C]

I wonder what worlds you all live in. I have lost kites in the manner described, but I don't think I have flown one since aged 8, so perhaps the wind has changed since then. ( I wonder how it is that it that everything can be said to reach windspeed except free kites.)

The kite no longer flies. It quickly reaches wind speed in the horizontal direction, while falling through the air in a somewhat erratic movement: it usually doesn't have a stable terminal velocity of fall, since it is constantly changing position and therefore presenting changing amounts of drag. If the wind is rapid, the kite will be carried a long way. With a long enough treadmill and still air, there's no difference: the kite will fall through the air and the kite flyer will be carried back by the treadmill, just as far as the kite was carried by the wind in the first example.

I also[qimg]http://www.internationalskeptics.com/forums/attachment.php?attachmentid=12812&stc=1&d=1233068893[/qimg]
The balloon is weighted to be not quite buoyant. Anubis is bored and has sent one of his many concubines to monitor the test.
On the treadmill, the balloon moves somewhat to the left, while Jane moves as shown. 'B' is the approximated motion due to the KE of the balloon and mass, eventually falling to the ground.

In the wind, the balloon is carried away to flight. Meteorological balloons carry instrument packs this way, so they will perform in this manner.

The main thing wrong with your diagram is the fallen balloon on the right. Why should one balloon descend faster than the other? In both cases, the balloon will descend slowly through the air at the same speed. In both cases, it will take the same time to reach the horizontal speed of the air. During this time, it is still moving backwards with respect to the air. This is what the movement B in your second diagram corresponds to. In the first diagram this should be represented by a period of acceleration: viewed from the frame of reference of the ground, the balloon starts with zero velocity, then accelerates until it reaches wind speed.

When the balloon finally touches the ground, the distance between it and Jane will be the same in both cases (assuming that the treadmill is long enough).

If we look at the first case from a frame of reference moving at the velocity of the wind, it look exactly like the second case. If we look at the second case from a frame of reference moving at the velocity of the surface of the treadmill, it will look exactly like the first case. Unless it falls so fast that it doesn't have enough time to accelerate, the balloon always reaches the speed of the air. The speed of the air is not an absolute value: it depends on your frame of reference.

 

[fredriks]

What isn't the same is what happens when you cut the string, since a kite is not normally built to remain a stable position in the air without being tethered.

You wrote normally and I guess that is true and I have also written that in several posts. Some kites might still glide after it is released. That was my whole point and I didn't expect to get several links to incomplete explanations about kites and how airplanes fly suggesting that my short comment was incorrect.

 

[Michael C]

You wrote normally and I guess that is true and I have also written that in several posts. Some kites might still glide after it is released. That was my whole point and I didn't expect to get several links to incomplete explanations about kites and how airplanes fly suggesting that my short comment was incorrect.

The links were in relation to Humber's original comment: "Kites can fly without string. A simple fact." A kite without string doesn't fly any more than a piece of paper or a plastic bag does.

 

[Dan O.]

I would like to make one last request of the people here who do know physics to take a look at my intro to newtonian physics document and check to see if I have any mistakes. It's about 50 pages or so. I originally posted it here since the thread title was "the validity of classical physics". I now realize that it's more a thread about humber's strange version of reality than anything else. But technically, it's on topic, so I figured I'd post one last request. Any feedback from folks who actually understand physics would be appreciated.

http://www.greglondon.com/newton/

Thanks

One big faux pas is that you introduce you own name for a unit of momentum. The scientific community has worked hard to standardize the language so scientists from around the world can communicate without creating the kind of confusion that sends multi-million dollar space craft crashing into planets.

The Newton second (N s) is perfectly adequate name for a unit of momentum so you can leave your shots at Hartman's bar.

 

[jjcote]

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?

 

[ThinAirDesigns]

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?

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

JB

 

[CNY_Dave]

I wonder what worlds you all live in. I have lost kites in the manner described, but I don't think I have flown one since aged 8, so perhaps the wind has changed since then. ( I wonder how it is that it that everything can be said to reach windspeed except free kites.)

I also[qimg]http://www.internationalskeptics.com/forums/attachment.php?attachmentid=12812&stc=1&d=1233068893[/qimg]
The balloon is weighted to be not quite buoyant. Anubis is bored and has sent one of his many concubines to monitor the test.
On the treadmill, the balloon moves somewhat to the left, while Jane moves as shown. 'B' is the approximated motion due to the KE of the balloon and mass, eventually falling to the ground.

In the wind, the balloon is carried away to flight. Meteorological balloons carry instrument packs this way, so they will perform in this manner.

Ho-
Lee-
Carp.

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

Dave

 

[humber]

The kite no longer flies. It quickly reaches wind speed in the horizontal direction, while falling through the air in a somewhat erratic movement: it usually doesn't have a stable terminal velocity of fall, since it is constantly changing position and therefore presenting changing amounts of drag. If the wind is rapid, the kite will be carried a long way. With a long enough treadmill and still air, there's no difference: the kite will fall through the air and the kite flyer will be carried back by the treadmill, just as far as the kite was carried by the wind in the first example.

Not all kites are the same, Micheal_C. Just because there is a NASA article about a certain type of kite, does not mean that all kites behave as you wish.
They do not.
It makes no difference, because you have already acknowledged that they do indeed continue to be airborne, even if unstable, as I have said. On the treadmill, once released, there is no wind at all, so the kite falls to ground. Windspeed is the same "frame" as being still on the ground in still air.
This too I have claimed. This is evidence.
Only the name has been changed,to windspeed, on the basis that there is a moving belt. That is not science, but magic.

The main thing wrong with your diagram is the fallen balloon on the right. Why should one balloon descend faster than the other?

Treadmill:
When dragged by the string, the balloon is airborne. There is enough lift generated by motion through the air to keep it aloft.
When the string is released, there is no airflow, so the balloon falls as shown.
It is an approximation, but the behavior is of that type.
Once the KE of the balloon has dissipated, there can be no horizontal motion, so gravity brings to ground.

In both cases, the balloon will descend slowly through the air at the same speed. In both cases, it will take the same time to reach the horizontal speed of the air. During this time, it is still moving backwards with respect to the air. This is what the movement B in your second diagram corresponds to. In the first diagram this should be represented by a period of acceleration: viewed from the frame of reference of the ground, the balloon starts with zero velocity, then accelerates until it reaches wind speed.

Nothing to do with the problem. It is the same as the kite, but using a balloon so as to avoid the tedious kites don't fly argument..
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.

When the balloon finally touches the ground, the distance between it and Jane will be the same in both cases (assuming that the treadmill is long enough).

(1) The real balloon does not touch the ground.
(2) For the period before the balloon hits the ground, the distance will be greater in real wind. If all else is equal, and they must be if the claim of equivalency is held, then the the balloon 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.

But of course the real balloon or kite will fly away and not hit the road.
This is because the treadmill wind is not like real wind. Real wind is independent of the road or strings or Anubis or Jane, but belt-wind is not.

If we look at the first case from a frame of reference moving at the velocity of the wind, it look exactly like the second case. If we look at the second case from a frame of reference moving at the velocity of the surface of the treadmill, it will look exactly like the first case. Unless it falls so fast that it doesn't have enough time to accelerate, the balloon always reaches the speed of the air. The speed of the air is not an absolute value: it depends on your frame of reference.

The differences are discernible from all frames. Belt, windspeed, ground (treadmill side). The treadmill is a belt. It behaves like one.

 

[humber]

You wrote normally and I guess that is true and I have also written that in several posts. Some kites might still glide after it is released. That was my whole point and I didn't expect to get several links to incomplete explanations about kites and how airplanes fly suggesting that my short comment was incorrect.

Yes. That is quite normal, Fredriks. Spurious information.

The point is that there are differences.
"Kites don't fly without string". Let's make that "carried, propelled, or held aloft by the wind". One of those happens, string or no string.
The point is that he treadmill\-wind depends upon object motion, produced by dragging, yes, dragging, that object through the air.
The result is that that belt-wind can never drive the cart on the belt. It is not possible.

 

[fredriks]

Kites don't fly without string". Let's make that "carried, propelled, or held aloft by the wind". One of those happens, string or no string.

You are wrong as usual.