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NoCleverName
QUOTE (meBigGuy+Sep 23 2007, 12:39 AM)
Haven't you guys ever heard of Schrodinger's plane?

Isn't it enshined in front of Hilbert's Hotel? That is, sometimes it can be seen there --- but only if you actually look for it.
yor_on
I thought that was a cat? How did he get the plane into the box?
Was it 'exotic'. :)
meBigGuy
QUOTE
I thought that was a cat? How did he get the plane into the box?
Was it 'exotic'.

You need to think outside the box.

Or is it inside? Oh God!! Did someone put Schrodinger's plane in Heisenburg's box? Or Not? So, now we can't tell whether the plane took off, or was never really on the runway. I'd hate to try to think of what Hilbert's converyer belt has to do with all this. But, I still insist the wheel bearings were frictionless.
yor_on
Not if the cat got stuck in them. On the other hand it would be a 'final' solution to that old question, wouldn't it?
I say. We do need new thinking here.. Why not start with this as a new axiom.

Ehh, we could name it 'bits and pieces'... maybe? Or 'bun in the box' nope, that wouldn't be proper terminology, would it? Something more relating to physics, hmmm?
fredrick
wow trippy, and I thought I had a lot of patience...

at least everyone here knows that an ASI actually measures AS--not fuel flow--right...?
meBigGuy
ASI?

Is that an Aether Sponge Interferometer?

I think the airplane takes off under "reasonable" conditions, everyone of significance now agrees, and the thread has died except for us bored day trippers trying to get to page 562 (and get our post count up).

Of course, merely saying that USUALLY fires it back up again.
Bloy
QUOTE (meBigGuy+Sep 24 2007, 02:12 AM)
ASI?

Is that an Aether Sponge Interferometer?

I think the airplane takes off under "reasonable" conditions, everyone of significance now agrees, and the thread has died except for us bored day trippers trying to get to page 562 (and get our post count up).

Of course, merely saying that USUALLY fires it back up again.

yes, I'm 99.9r% positive that Atl5p will still have something to add....
QUOTE (meBigGuy+Sep 24 2007, 04:12 AM)
ASI?

Is that an Aether Sponge Interferometer?

I think the airplane takes off under "reasonable" conditions, everyone of significance now agrees, and the thread has died except for us bored day trippers trying to get to page 562 (and get our post count up).

Of course, merely saying that USUALLY fires it back up again.

I'm not sure what you mean by reasonable conditions, but I did post a variation of the OP recently that tried to remove some of its ambiguity.

Funny thing, not a SINGLE response.

It appears that few are really interested in the actual physics questions.

Arthur
Bloy
QUOTE (adoucette+Sep 20 2007, 08:32 PM)
IMHO the statement "The plane moves in one direction, while the conveyer moves in the opposite direction."

Does NOT necessarily imply that the plane must actually move.

It appears, in the construct of the problem, that this is just stating that the two are headed in opposite directions.

I think its no different than this statement:

"The plane is pointed opposite to the direction that the band conveyer will rotate."

Why?

Because of the last sentence:

"Will it be able to run up and take off?"

But "be able to run up" is the same as "be able to MOVE".

So it appears that the question is really asking is "will the plane be able to move?".

My point being is that any arguments that are simply based on the fact that the OP says the plane moves are more of a semantics arguement than a physics arguement.

Thus the NEW IMPROVED OP: (    )

A plane is standing on runway that can move (some sort of band conveyer). The plane is pointed opposite to the direction that the band conveyer will rotate. This conveyer has a control system that attempts to counter any movement by the plane by instantly accelerating the belt in the opposite direction.

The question is:

Will the plane take off or not? Will it be able to run up and take off?

Arthur

Is this your "take" on the OP?
...so we'll just forget about the OP's condition...
"This conveyer has a control system that tracks the "plane speed" and tunes the speed of the conveyer to be exactly the same (but in opposite direction)."

You don't mean that the plane doesn't necessarily have any actual speed, do you?
That would mean that the conveyor doesn't have any speed either.

interpretation..interpretation....misconfiguration.

No wonder you didn't get any responses.
No bloy, I created a NEW version of the OP that does not reflect on the original, ambiguously worded, OP.

I notice you did NOT try to answer the new question though.

Arthur

.
Bloy
QUOTE
This conveyer has a control system that attempts to counter any movement by the plane by instantly accelerating the belt in the opposite direction

okay, I'll bite, but first I have a question...
What rate of accelertion does the conveyor instantly accelerate at?

oops..one more question...

..and at what rate does the rate of acceleration change?
NoCleverName
QUOTE (Bloy+Sep 24 2007, 07:13 PM)
..and at what rate does the rate of acceleration change?

Bloy, I think the technical term is "jolt" --- which would also seem to be your drink of choice.
QUOTE (Bloy+Sep 24 2007, 03:13 PM)

okay, I'll bite, but first I have a question...
What rate of accelertion does the conveyor instantly accelerate at?

oops..one more question...

..and at what rate does the rate of acceleration change?

While we are dealing with a typical plane, the problem imposes no limits to how fast the belt can accelerate.

But since I figure you will nit pick and not answer the question, you might try THIS variation of the OP instead.

Could you build a treadbelt that could stop a typical aircraft from taking off?

Arthur
Bloy
QUOTE (adoucette+Sep 24 2007, 01:56 PM)

Could you build a treadbelt that could stop a typical aircraft from taking off?

Arthur

no.

Why not?

Arthur
Atl5p
QUOTE (Trippy+Sep 21 2007, 11:10 PM)
It wasn't me suggesting that we use airspeed in the first place.

If you actually read my post, you will see that I stated that I thought the best option was to measure the plane's soeed RELATIVE TO THE GROUND.

I also stated that the experiment should be conducted on a windless day so that the air speed, and speed relative to the ground were the same.

It was AT5LP that was blithering on about IAS.

What I was saying was that if we measure the speed of the plane relative to the moving surface of the treadmill we set up a positive feedback loop, or a paradox, that results in the treadmill accelerating to an infinite speed (well, since that's impossible, maybe a hair below 186,000 miles per second).

QUOTE
One is a consequence of gallilean relativity, the other is a consequence of the forces acting on the plane.
The fact is this: A very fast belt will hold a plane to 0 IAS.

Then you said:

QUOTE (->
 QUOTE One is a consequence of gallilean relativity, the other is a consequence of the forces acting on the plane.The fact is this: A very fast belt will hold a plane to 0 IAS.

Then you said:

What I was saying was that if we measure the speed of the plane relative to the moving surface of the treadmill we set up a positive feedback loop, or a paradox, that results in the treadmill accelerating to an infinite speed (well, since that's impossible, maybe a hair below 186,000 miles per second).

First statement:
"A very fast belt will hold a plane to 0 IAS"

What is going on there? How fast is the plane going in relation to the treadbelt? 600mph.
How fast is the treadbelt spinning? 600mph.

The treadbelt has matched the speed of the plane (in relation to the surface of the treadbelt).

Thus, Plane has 0 IAS.

Second Statement:

You now claim that your first statement is impossible....infinite speed paradox loop smashing space and time. Hey bud...that's a far cry from 600mph!!!

Care to explain?

You can either hold a plane to 0 IAS with a treadbelt.
OR
You can create an infinate loop.

ONLY ONE WILL FIT.

CANNOT HAVE BOTH.

NoCleverName
QUOTE (adoucette+Sep 24 2007, 08:13 PM)
Why not?

Arthur

Because any practical material that can be a belt (i.e., can bend around the drive rollers) doesn't have enough tensile strength to resist tearing apart as the forces increase with speed and load. In the "real" world, this limits belt speeds to fairly low speeds (some of the limit is for safety).

Remember the third law about equal and opposite forces: if the belt is going to stop the plane, it has to be strong enough to withstand the same force internally --- because it has to apply that force to the plane. Let alone the force on it simply from its entire mass being driven by its power system.

A few hundred pages ago I came up with the calculations. Can't remember, maybe the speed limit was 10-15mph.
meBigGuy

After you restated the problem, I responded. You must have missed it. But, no-one cares about a restatement anyway.
My comment was
QUOTE
My "list of 4" apply to this statement of the problem also, unless the speed of the belt and the friction in the tire system and belt are enough to overcome the power of the engine. Of course, another possibility not mentioned is that if the belt moves fast enough, and drags enough air with it, the plane might take off even if it is stationary relative to the ground (before the wheel bearings burn out). But, again, all of this is not in the spirit of the original problem, and does not expose the simple logical fallicy that the problem was designed to expose. I simply submit my list of 4 to overcome that specific fallicy.

Alt5p already admitted the plane will take off under #4, and cannot explain how adding a reasonable amount of friction to the wheels will stop it from taking off, other than what I ALREADY wrote in my response to him and you. He insists on calling names and playing word games, and has very poor analytical and communication skills..

I will repeat my statement of the issues and treatment of friction

1. IMAGINE A PLANE SUSPENDED BY LEVITATION 3 FT OVER THE BELT.
2. CAN THAT PLANE ACHIEVE WINGED FLIGHT OVER A MOVING BELT FOR ANY REASONABLE BELT SPEED?
3. NOW, IMAGINE EXTENDING FRICTIONLESS, OR NEARLY SO, WHEELS TO THE BELT.
4. CAN THAT PLANE STILL ACHIEVE WINGED FLIGHT?

If you think the above plane cannot take off, please state, in 0 words or more, whether you answered NO to #2 or #4, and why, or describe why you think the above is not a valid description of the issues.

Again, regarding friction, unless the speed of the belt and the friction in the tire system and belt are enough to overcome the power of the engine, the plane will take off. But long before that the tire system would explode (1hp = 746 watts)

For humor, I also submit that if the belt moves fast enough, and drags enough air with it, the plane might take off even if it is stationary relative to the ground (before the wheel bearings burn out).

Any interpretation of the OP can be applied. The plane will take off, or not, as I have described.

In my opinion, adding friction or infinite belt speed is a ridiculous interpretation. To those that wish to be ridiculous, at least realize you are being so.

@alt5p
Please count the words in this post for me. You seem to do that well, and I'm trying to keep track. I look forward to your usual abusive, long, substance free response. I know it makes you feel superior, and you need as much of that as you can get.

QUOTE (NoCleverName+Sep 24 2007, 07:15 PM)
Because any practical material that can be a belt (i.e., can bend around the drive rollers) doesn't have enough tensile strength to resist tearing apart as the forces increase with speed and load. In the "real" world, this limits belt speeds to fairly low speeds (some of the limit is for safety).

Remember the third law about equal and opposite forces: if the belt is going to stop the plane, it has to be strong enough to withstand the same force internally --- because it has to apply that force to the plane. Let alone the force on it simply from its entire mass being driven by its power system.

A few hundred pages ago I came up with the calculations. Can't remember, maybe the speed limit was 10-15mph.

Aw come on. You can CERTAINLY devise a belt system that can achieve FAR greater speeds than 15 mph.

They are talking about building Rotorvators built out of fiber that would sling things into orbit that weigh thousands of pounds.

http://en.wikipedia.org/wiki/Tether_propulsion

Please note, per the 3rd law, the static thrust of aircraft is not that high.

That's why they need a long runway to take off to begin with.

Arthur
QUOTE (meBigGuy+Sep 24 2007, 07:41 PM)

After you restated the problem, I responded. You must have missed it. But, no-one cares about a restatement anyway.
My comment was

I did miss it, sorry.

So If I understand your response, a belt can stop a plane from taking off IF

QUOTE
the friction in the tire system and belt are enough to overcome the power of the engine.

Thanks.

Arthur
NoCleverName
QUOTE (adoucette+Sep 25 2007, 12:00 AM)
Please note, per the 3rd law, the static thrust of aircraft is not that high.

Oh, really ... a GE 90 produces 400,000 N. A really good belt material has a tensile strength of 8500 N/mm. Practical belt thicknesses range up to 30-40 mm. And that's just for 4-5 foot widths. You'd need more thickness to deal with the need of the material to support itself without troughing. But thickness increases weight --- and heat --- let alone bending radius. Greater width means greater mass to pull at the same yield strength. The technical difficulties quickly start to pile up. More and more power begins to go into simply driving the thing while effective load suffers. A conveyor is not the same thing as a fan belt (which is subject just to tension and doesn't have to carry a load on its back --- not to mention a fan belt has the luxury of being driven on three sides not just one). Then we've got the enginerring problem of something that big and massive better be moving in a pretty straight line --- no crosstrack error --- or there will be excessive wear and heat buildup.
Look the question whose point is can you devise a belt system that can keep a 777 from flying.

Try thinking TYPICAL small plane.

Clearly its NOT going to be easy.

It might even be impossible.

But don't stack the decks against it from the start.

Arthur
Derek1148
In that a plane is pushed through the air by its propulsion system (not driven by the wheels like a car), unless there is a malfunction of the wheels, the plane will take off. The issue is the physics of flight. Certainly a conveyor could be designed that would damage the axles, wheels, or tires (with catastrophic results), if that is the point one is trying to make.
NoCleverName
It just puts it in stark perspective faster. Mining belts top out at about 1,500 feet per minute. What, 20 mph? Making a wide, moving surface capable of simply transporting weight is trouble enough. And then you want it to actually, via friction, generate force to hold back a plane? That same frictional force is going to have to be in the drive rollers, too, with the attendent losses generating heat --- a lot of heat --- which can't be too good.

And if I actually knew anything about engineering I could probably make the idea even more laughable.
gmilam
I'm not an engineer, but it seems logical to me that any vulnerability that you try to exploit in the plane is also going to have to be overcome by the conveyor belt.

May the force be with you.
meBigGuy
Assume the wheels have enough friction that the plane cannot move. Then, the belts doesn't even have to move.

Assume the plane can JUST barely take off with no belt motion (due to an engine not firing on all cylinders, like some posters here). Then belt motion can stop it.

Assume no one actually observes the plane. Then it can both take off and not take off (Schrodinger's plane).

So what! The solution is in, the thread must die, and I must have the last word.

QUOTE (NoCleverName+Sep 24 2007, 09:21 PM)
It just puts it in stark perspective faster. Mining belts top out at about 1,500 feet per minute. What, 20 mph? Making a wide, moving surface capable of simply transporting weight is trouble enough. And then you want it to actually, via friction, generate force to hold back a plane? That same frictional force is going to have to be in the drive rollers, too, with the attendent losses generating heat --- a lot of heat --- which can't be too good.

And if I actually knew anything about engineering I could probably make the idea even more laughable.

Ok,

So your answer is you can't physically build a belt that could go fast enough.

Fine.

Now assume you COULD build a belt that could go as fast as you want, could you NOW keep the plane from taking off?

Arthur
meBigGuy
WOW --- I answered that question in two ways, three times. Doesn't my answer count???

1. If the speed of the belt and the friction in the tire system and belt are enough to overcome the power of the engine. Of course.

2. If the belt moves fast enough, and drags enough air with it, the plane might take off even if it is stationary relative to the ground (before the wheel bearings burn out).

3. Also, read above regarding Schrodingers plane (do you know about the paradox of Schrodinger's cat ?)

These are VERY SIMPLE straightforward issues. Why are you not willing to think for yourself and reach these conclusions. Or, is this a "test question" where you play dumb to get the other guy to admit something so you feel smarter?

Sheesh, if you don't have any real issues, give it up. Do something that requires thought.

Go analytically prove which is bigger e^pi or pi^e (e to pi power or pi to e power where e is the base of the natural logarithms).

schnoppledock
QUOTE
ASI?

heh... take a guess:

ASI AARP Services Inc.
ASI Access Server Integration
ASI Accuracy Support Infrastructure
ASI Achats Service International (Niger)
ASI Acquisition Streamlining Initiative
ASI Acrobat Systems Incorporated
ASI Actor Sensor Interface
ASI Actuarial Society of India
ASI Actuator Sensor Interface
ASI Addiction Severity Index (substance abuse)
ASI Adhesives & Sealants Industry (magazine)
ASI Advanced Studies Institute of NATO
ASI Advertising Specialty Institute (promotional products industry Association)
ASI Aerospace Science Instructor (AFJROTC)
ASI Aerospace Studies Institute
ASI Agencia de Seguridad Israelí (security agency)
ASI Agencia Spatiale Italiano
ASI Agency Safety Initiative (NASA)
ASI Agency Selection Inventory
ASI Agenzia Spaziale Italiana (Italian Space Agency)
ASI Agri Sales, Inc.
ASI Ahorro Sistematico Integral (Mexico)
ASI Air-Sea Interaction
ASI Aircraft Station Interface
ASI Aircraft Supplementary Information (Royal Australian Air Force)
ASI Aircraft System Interface
ASI Airspeed Indicator
ASI Alarm Status Indicator
ASI Albert Schweitzer Institute (Hamden, Connecticut)
ASI Alenia Marconi Systems, Inc.
ASI Alex Software Inc.
ASI Algoma Steel Inc.
ASI Alternate Space Inversion
ASI Amended Shipping Instrument
ASI America's Shield Initiative
ASI American Share Insurance
ASI American Sheep Industry Association
ASI American Society of Indexers
ASI American Statistics Index (LexisNexis publication)
ASI American Supplier Institute
ASI Amorphous Silicon
ASI Ampere-Second Integration
ASI Analytical Services, Incorporated
ASI Apex Security & Investigations
ASI Application Solutions Inc.
ASI Applied Systems Intelligence, Inc
ASI Arc Second Imager
ASI Archaeological Survey of India
ASI Architect's Supplemental Instructions
ASI Architectural and Surveying Institute
ASI Armor Systems International
ASI Army Space Institute
ASI Arterial Stiffness Index
ASI Asphaltene Stability Index
ASI assign and display switch initialization (US DoD)
ASI Assign Switch Initialization
ASI Assistant Sub Inspector
ASI Assisted Self Install
ASI Associate of the Securities & Investment Institute
ASI Association of Surgeons of India
ASI Astrological Society of India
ASI Asynchronous SCSI Interface
ASI Asynchronous Serial Interface (digital television)
ASI Atlanta Suzuki Institute (Atlanta, Georgia)
ASI Atlantic Studies Institute (University of Michigan)
ASI ATM Service Interface (Cisco)
ASI ATV (All Terrain Vehicle) Safety Institute
ASI Audience Studies, Inc
ASI Augmented Spark Igniter
ASI Austin Semiconductor Incorporated
ASI Austral Summer Institute
ASI Australian Steel Institute (North Sydney)
ASI Author Services, Inc
ASI Authorized Service Interruption (DOD)
ASI Automated Shore Interface
ASI Automated System Initialization
ASI Automatic SACCS Interface
ASI Automotive Services, Inc.
ASI Aviation Safety Inspector (FAA)
ASI Axial Scientific Instrument
ASI Axial Shape Index (nuclear reactors)
ASI Azimuth Speed Indicator

ASI = Airspeed Indicator

Elsewhere there is a discussion that evolved from this plane-treadmill discussion regarding whether ASI's indicate airspeed or fuel flow...
meBigGuy
I still think my Schrodinger plane is funny.
schnopples
QUOTE
I still think my Schrodinger plane is funny.

hmm... well, I'm not so sure...

its funny, but somehow not funny at the same time.
Atl5p
No Clever Name

Interesting how you can accept a super-duper treadmill which can shoulder the burden of a fullsized aircraft, yet the concept of that exact same treadbelt ‘holding together’ is impossible.

Folks, this was the guy that went to see ‘Superman Returns’, saw the hero fly through outerspace, and bounce bullets off his eye….but the second he caught that airplane and set it down in the baseball field, he stood up and shouted “Hey, no WAY!! That plane’s just too huge, even for Superman”.

QUOTE

MeBigGuy
http://forum.physorg.com/index.php?showtop...ndpost&p=264655
I already addressed your concerns regarding friction in the second half of the post. But, as it turns out, you really do have this wrong. You totally missed what my list points out.

So, you think that adding friction to the tire system in #4 will somehow stop the plane from taking off. Think about that carefully.

Your short reply was appreciated, even though it is obvious that you did not read the second half of what you quoted where I addressed friction.

MeBigGuy
http://forum.physorg.com/index.php?showtop...ndpost&p=264222

@Alt5p
You agree the plane takes off under #4, then the problem is answered. You want to quibble about the details, I'm sure many here will comply. But your BS is not in the spirit of the original problem. You want to post a new problem, or new wording, feel free. I'll certainly reply. But, my job is done once anyone answers it will take off after #4, since there are and have been many that initially disagreed. I look forward to your long, abusive and typically substance-free reply. (BTW, how many words in THIS post)

……. unless the speed of the belt and the friction in the tire system and belt are enough to overcome the power of the engine.

So, you think that adding friction to the tire system in #4 will somehow stop the plane from taking off. Think about that carefully.

the speed of the belt and the friction in the tire system and belt are enough to overcome the power of the engine

NoCleverName
QUOTE (Atl5p+Sep 25 2007, 06:18 PM)
Interesting how you can accept a super-duper treadmill which can shoulder the burden of a fullsized aircraft

No, I don't, troll. In the future, feel free to never respond to any of my posts.
Atl5p
QUOTE (NoCleverName+Sep 25 2007, 02:35 PM)
No, I don't, troll. In the future, feel free to never respond to any of my posts.

Oh yeah...rite....

The OP says
QUOTE
A plane is standing on runway that can move (some sort of band conveyer).

and you yell "STOP RIGHT THERE!!! SUCH A RUNWAY CANNOT EXIST"

wow....how insightful.

Feel free to not post in this thread anymore.
Bloy
QUOTE (Atl5p+Sep 25 2007, 02:57 PM)
Oh yeah...rite....

The OP says

and you yell "STOP RIGHT THERE!!! SUCH A RUNWAY CANNOT EXIST"

wow....how insightful.

Feel free to not post in this thread anymore.

Hi there, NoCleverName....

watch out or you too will be listed in Atl5p's signature....

Shambles
If you think of the problem in terms of why a plate stays on a table when the tablecloth is whipped from under it, it is obvious that the plane will take off.

The only time it wouldn't would be if the friction of the wheels and bearings meant that the conveyor belt had a direct influence over the plane.
Bloy
Time out!!
NoCleverName
QUOTE (Bloy+Sep 25 2007, 09:18 PM)
Time out!!

Hmmm, is that why Atl5p seems to be offline, hmmm.

As far as fearing being in the sig line, 5p already used some of my material against my wishes in the sig for quite a while. Actually, I treasure my negative feedback from Zephir and Nick more.
Derek1148
QUOTE (Bloy+Sep 25 2007, 09:18 PM)
Time out!!

Do you believe he should been provided a forum on a college campus?
Bloy
QUOTE (Derek1148+Sep 25 2007, 07:10 PM)
Do you believe he should been provided a forum on a college campus?

yes and I think Bush should at least tryto discuss with him. One can learn more indepth about a person in conversation. ...find out just how he views things.

We can listen but we don't have to absorb.
meBigGuy
QUOTE
the speed of the belt and the friction in the tire system and belt are enough to overcome the power of the engine

JUST AS I SAID ---- in that post you quoted and did not read, and maybe 4 other posts. You are truly a case in incomprehension. Take your adderol.

Why don't you go back and read how many times I already said that same sentence, including in my last post to you where I indicated I had said it 3 times already.

I expect you will actually go back and actually count them, so you can post about how I exagerate.

Trippy
QUOTE (Atl5p+Sep 25 2007, 09:15 AM)
Then you said:

First statement:
"A very fast belt will hold a plane to 0 IAS"

What is going on there? How fast is the plane going in relation to the treadbelt? 600mph.
How fast is the treadbelt spinning? 600mph.

The treadbelt has matched the speed of the plane (in relation to the surface of the treadbelt).

Thus, Plane has 0 IAS.

Second Statement:

You now claim that your first statement is impossible....infinite speed paradox loop smashing space and time. Hey bud...that's a far cry from 600mph!!!

Care to explain?

You can either hold a plane to 0 IAS with a treadbelt.
OR
You can create an infinate loop.

ONLY ONE WILL FIT.

CANNOT HAVE BOTH.

You're the one talking out of the hole in your arse.

Both fit, but you're apparently too thick to see it.

I have always specified that I am assuming that the speed of the plane (and logically the belt) are measured with respect to the ground.

Poof.

The plane is going full throttle.
The plane has 0 velocity relative the ground.
The treadbelt has 600 mph velocity, relative to the ground.

The only problem here is a neurological one, and it's firmly in your court.
NoCleverName
I should point out that, as far as physics is concerned, that if the plane is not moving then the plane's wheels act to slow the belt, not the other way around. The belt, as it is driving the wheels, observes the frictional forces of the tires. The plane, on the other hand, observes the frictional forces of the wheel bearings. True, the mechanical action of the bearings may be affected by the torque load of the tire and thus may lose efficiency.

So, at some point conceivably enough inefficient wheels together can absorb the power of the engine (which is the belt) driving them.

Now, before anyone gets all excited about Newton's third law and attempts to say that the frictional force created by the belt must be opposed by the plane --- think again. The reaction force is accepted as a torque on the wheels and is converted to rotational kinetic energy. Only that part of the torque which is not exactly perpendicular to the radius of the wheel gets converted to a "linear" force and must be opposed by the plane. In general, some force gets converted that way because the tire gets distorted and the contact patch doesn't reside perfectly under the wheel.

While it may seem counterintuitive, one must remember what is moving and what isn't. The belt is moving and doing "work". If the plane is not moving then it is not doing work. (The planes engines are doing work moving air). Whatever is doing the work is expending the power (work/time).
Guest_anon
QUOTE (NoCleverName+Sep 26 2007, 12:52 PM)
While it may seem counterintuitive, one must remember what is moving and what isn't. The belt is moving and doing "work". If the plane is not moving then it is not doing work. (The planes engines are doing work moving air). Whatever is doing the work is expending the power (work/time).

Errr...

The treadbelt's motor is doing work, not the belt itself. Just as the plane is doing work displacing air... A "belt" is this thing we use to:

1. Keep our pants up.
2. Transfer rotational force between objects.
NoCleverName
QUOTE (Guest_anon+Sep 27 2007, 12:50 AM)
Errr...

The treadbelt's motor is doing work, not the belt itself.

Are you sure ... or is it the power plant that's suppling the electricity?
Atl5p
QUOTE (Trippy+Sep 26 2007, 05:14 AM)
You're the one talking out of the hole in your arse.

Both fit, but you're apparently too thick to see it.

I have always specified that I am assuming that the speed of the plane (and logically the belt) are measured with respect to the ground.

Poof.

The plane is going full throttle.
The plane has 0 velocity relative the ground.
The treadbelt has 600 mph velocity, relative to the ground.

The only problem here is a neurological one, and it's firmly in your court.

As long as you realize that the treadbelt has an influence on the plane, then I'm cool with it.

Hey, if you want to put the plane on a treadbelt, then measure it's speed relative to the earth's crust, then that's your silly belief....as long as you realize that the plane WILL need to expend more effort to achieve the same airspeed, however insignificant.

And as long as you realize that when the control system DOES measure plane's speed in relation to the runway it's traversing, under this situation the treadbelt WILL hold the plane to zero IAS.

And as long as you continue to fail to point out to me exactly in the OP where it specifies HOW the plane's speed is determined, you will continue to fail in proving the de facto standard for which this problem measures plane's speed.

At least you aren't one of those who continues to ramble on and on about 'extending Frictionless tires' from the plane.....holleeyyyy she-at!

Sure, if you extended "FRICTIONLESS" tires unto the treadbelt, then the treadbelt could never have any influence on the plane via those tires.

But I think all would agree that 'frictionless' tires are not to be included in any reasonable explination of this problem.

The purpose of the problem is to determine if people realize whether or not a non-driven wheel IS or ISN'T affected by frictional forces related to increasing speed.

Many many people are still failing this test.

However it is refreshing to see even so many 'FlyBoys' DO in fact understand these affects, yet are however stuck on the semantics of the question, trying to force it into a 'trick question' by making the plane move through the air by sheer inturpretation of the setup....hey, whatever floats their boat..
bm1957
QUOTE (Atl5p+Sep 27 2007, 02:11 PM)
But I think all would agree that 'frictionless' tires are not to be included in any reasonable explination of this problem.

I'd have to disagree there. I think that most people would assume that given the size of the frictional force compared to the thrust of the engines, the frictional force would be negligible and frictionless tires (zero friction at the bearings, not at the ground) would be a fair assumption. As would light tires, which removes the requirement of force to spin them.

I also think that's the spirit in which the question is intended.
egnorant
QUOTE (Atl5p+Sep 27 2007, 02:11 PM)
As long as you realize that the treadbelt has an influence on the plane, then I'm cool with it.

The belt has no influence on the plane in the original question.
It is clear that all the belt does in match the speed of the plane!
That means it is equal to the speed of the plane.
There is nothing that points anyone to believe that the belt alters, increases, decreases or has any effect on the speed of the plane.

QUOTE
Hey, if you want to put the plane on a treadbelt, then measure it's speed relative to the earth's crust, then that's your silly belief....as long as you realize that the plane WILL need to expend more effort to achieve the same airspeed, however insignificant.

By your use of the word silly it appear that you believe this to be the incorrect
answer. Unless you wish us to believe you are silly and correct.
No need to understand the effort involved at all.
Use 2 planes..one fully loaded and one empty and have them match speed.
Is the heavier one slower at 30 mph because it takes more effort to be at 30 mph?
(Hint....NO)

QUOTE (->
 QUOTE Hey, if you want to put the plane on a treadbelt, then measure it's speed relative to the earth's crust, then that's your silly belief....as long as you realize that the plane WILL need to expend more effort to achieve the same airspeed, however insignificant.

By your use of the word silly it appear that you believe this to be the incorrect
answer. Unless you wish us to believe you are silly and correct.
No need to understand the effort involved at all.
Use 2 planes..one fully loaded and one empty and have them match speed.
Is the heavier one slower at 30 mph because it takes more effort to be at 30 mph?
(Hint....NO)

And as long as you realize that when the control system DOES measure plane's speed in relation to the runway it's traversing, under this situation the treadbelt WILL hold the plane to zero IAS.

And you seem to like this for the answer.
The application of the relationships described here would prevent the plane from having any airspeed. No need to understand the forces at all.
Any force that is applied that releases the plane from 0 airspeed would violate this GIVEN situation.

QUOTE
And as long as you continue to fail to point out to me exactly in the OP where it specifies HOW the plane's speed is determined, you will continue to fail in proving the de facto standard for which this problem measures plane's speed.

Yet you have no problem determining the speed of the belt correctly despite a similar lack of specific reference.
Then you take one of your self declared unspecified methods and declare it correct while another unspecified method is incorrect.
For the "unspecified" argument to be valid you must declare that both the above versions are incorrect...for the same reason.

QUOTE (->
 QUOTE And as long as you continue to fail to point out to me exactly in the OP where it specifies HOW the plane's speed is determined, you will continue to fail in proving the de facto standard for which this problem measures plane's speed.

Yet you have no problem determining the speed of the belt correctly despite a similar lack of specific reference.
Then you take one of your self declared unspecified methods and declare it correct while another unspecified method is incorrect.
For the "unspecified" argument to be valid you must declare that both the above versions are incorrect...for the same reason.

At least you aren't one of those who continues to ramble on and on about 'extending Frictionless tires' from the plane.....holleeyyyy she-at!
Sure, if you extended "FRICTIONLESS" tires unto the treadbelt, then the treadbelt could never have any influence on the plane via those tires.

But I think all would agree that 'frictionless' tires are not to be included in any reasonable explination of this problem.

Just as friction has no place in the solution.

30(plane)=30(belt)
Should something else alter the speed of one, the other changes also.
29=29
No doubt that there are forces that are needed to produce the 30 in the first place, but we only need to know the result.

QUOTE
The purpose of the problem is to determine if people realize whether or not a non-driven wheel IS or ISN'T affected by frictional forces related to increasing speed.

No, it isn't the purpose.
That is a related side effect that you have adopted.

QUOTE (->
 QUOTE The purpose of the problem is to determine if people realize whether or not a non-driven wheel IS or ISN'T affected by frictional forces related to increasing speed.

No, it isn't the purpose.
That is a related side effect that you have adopted.

Many many people are still failing this test.

Not many, not many at all.

QUOTE
However it is refreshing to see even so many 'FlyBoys' DO in fact understand these affects, yet are however stuck on the semantics of the question, trying to force it into a 'trick question' by making the plane move through the air by sheer inturpretation of the setup....hey, whatever floats their boat..

It is disheartening to see some misinterpret the original question and force the plane to remain motionless.
At least my boat floats.

Bruce

NoCleverName
QUOTE (egnorant+Sep 27 2007, 05:52 PM)
The belt has no influence on the plane in the original question.
It is clear that all the belt does in match the speed of the plane!
That means it is equal to the speed of the plane.
There is nothing that points anyone to believe that the belt alters, increases, decreases or has any effect on the speed of the plane.

That is an important point; the problem implicitly states the belt has no influence on the plane. The fact that the belt "matches the plane's speed" indicates the belt made no effort whatsoever to prevent the plane from reaching a speed (however measured) in the first place. There is nothing in the problem that states the belt will later take on an entirely different characteristic and try to hold the plane back. There is no reason to believe the belt will act any differently in the future than it did in the past --- when it didn't restrain the plane.

The fact is, the problem states nothing about the belt other than it "matches speed." Any characteristics beyond that are inventions that exceed the problem specification.
Derek1148
QUOTE (NoCleverName+Sep 27 2007, 06:26 PM)
That is an important point; the problem implicitly states the belt has no influence on the plane. The fact that the belt "matches the plane's speed" indicates the belt made no effort whatsoever to prevent the plane from reaching a speed (however measured) in the first place. There is nothing in the problem that states the belt will later take on an entirely different characteristic and try to hold the plane back. There is no reason to believe the belt will act any differently in the future than it did in the past --- when it didn't restrain the plane.

The fact is, the problem states nothing about the belt other than it "matches speed." Any characteristics beyond that are inventions that exceed the problem specification.

Based on the physics of flight, is it possible for the plane to remain stationary with its propulsion system generating full forward thrust and the wheels of the plane freely rotating? Would it not seem to be a scientific paradox that the reverse motion of the conveyor belt would create such an effect?
egnorant
QUOTE (Derek1148+Sep 27 2007, 07:01 PM)
Based on the physics of flight, is it possible for the plane to remain stationary with its propulsion system generating full forward thrust and the wheels of the plane freely rotating? Would it not seem to be a scientific paradox that the reverse motion of the conveyor belt would create such an effect?

Yes it is possible. Just use simple physics.
It would be a simple balance of power.
Plane just remains stationary with some device spinning the wheels.

Not a paradox at all! It would be a simple balance of power.

Bruce
Derek1148
QUOTE (egnorant+Sep 27 2007, 07:49 PM)

Yes it is possible. Just use simple physics.
It would be a simple balance of power.
Plane just remains stationary with some device spinning the wheels.

Not a paradox at all! It would be a simple balance of power.

Bruce

I don’t believe the forces involved would be in direct opposition to each other. The plane is being pushed through the air not driven by the wheels.
NoCleverName
QUOTE (Derek1148+Sep 27 2007, 07:01 PM)
Based on the physics of flight, is it possible for the plane to remain stationary with its propulsion system generating full forward thrust and the wheels of the plane freely rotating? Would it not seem to be a scientific paradox that the reverse motion of the conveyor belt would create such an effect?

The physics of flight has nothing to do with it.

To make a wheel spin at a given rate you need to apply only enough torque to get the wheel's moment of inertia going (plus overcoming any bearing friction, rolling resistance, or other braking actions). After that, adding "more power" will only make the wheel spin faster, not with more "authority" at the same speed.

Thus, since the wheel has only the rotational kinetic energy (1/2 Iw^2) commensurate with a given speed, it only has the same energy to give up for any other purpose (unless, of course you are member "Limon" --- then energy springs from thin air!).

So, if it took, say, 10HP to get a given wheel spinning at x mph, no more than 10 HP can be extracted from it.

How work may be extracted from the wheel depends on what forces are opposing rotation. Rolling resistance, for example, is a deformation in the wheel and much of that energy is dissipated as heat and is lost. Anything that is "brake-like", however, is a counteracting torque and that force is available.

A spinning wheel is not, in itself, an impediment to additional forces trying to make it go yet faster. At least at non-relativistic speeds, the moment of inertia (angular rotation analog to "mass") is velocity independent. Thus, even if a belt were to whip up the wheel's speed, the plane would not perceive that speed in itself to be an issue. From a "total force" perspective, however, any "braking action" counter torques created by the existing rotation are real forces to be dealt with. On the other hand, to be meaningful these counter torques would truly have to be of a magnitude simliar to actually applying the brakes, so that isn't too realistic.

Another way to look at it is if the belt was causing the wheel to rotate at rate w but now you wanted it to rotate at a faster rate, either the plane or the belt could contribute the needed power and in either case the added power would be the same.

The bottom line is "what goes in is also the most that can go out" so only as much work that went in to getting a wheel upto speed is the maximum amount of work the wheel can do against any resistive force.
Derek1148
QUOTE (NoCleverName+Sep 27 2007, 08:14 PM)
The physics of flight has nothing to do with it.

To make a wheel spin at a given rate you need to apply only enough torque to get the wheels moment of inertia going (plus overcoming any bearing friction, rolling resistance, or other braking actions). After that, adding "more power" will only make the wheel spin faster, not with more "authority" at the same speed.

Thus, since the wheel has only the rotational kinetic energy (1/2 Iw^2) commensurate with a given speed, it only has the same energy to give up for any other purpose (unless, of course you are member "Limon" --- then energy springs frm thin air!).

So, if it took, say, 10HP to get a given wheel spinning at x mph, no more than 10 HP can be extracted from it.

How work may be extracted from the wheel depends on what forces are opposing rotation. Rolling resistance, for example, is a deformation in the wheel and much of that energy is dissipated as heat and is lost. Anything that is "brake-like", however, is a counteractiing torque and that force is available.

A spinning wheel is not, in itself, an impediment to additional forces trying to make it go yet faster. At least at non-relativistics speeds, the moment of inertia (angular rotation analog to "mass") is velocity independent. Thus, even if a belt were to whip up the wheel's speed, the plane would not perceive that speed in itself to be an issue. From a "total force" perspective, however, any "braking action" counter torques created by existing rotation are real forces to be dealt with. On the other hand, to be meaniningful these counter torques would truly have to be of a magnitude simliar to actually applying the brakes, so that isn't too realistic.

Another way to look at it is if the belt was causing the wheel to rotate at rate w
but now you wanted it to rotate at a faster rate, either the plane or the belt could contribute the needed power and in either case the added power would be the same.

The bottom line is "what goes in is also the most that can go out" so only as much work that went in to getting a wheel upto speed is the maximum amount of work the wheel can do against any resistive force.

The wheels are not doing work. The wheels are simply there to reduce friction.
NoCleverName
QUOTE (Derek1148+Sep 27 2007, 08:17 PM)
The wheels are not doing work. The wheels are simply there to reduce friction.

The wheels clearly have the ability to do work as they can have kinetic energy and this energy can be applied as a force over distance = work. Now, granted that most of the time we are doing work against the wheel to give it rotational kinetic energy, but once its got it, it can do work.

But let me reiterate the wheel can only do as much work as it has kinetic energy so once the "switch is turned off" to the supply of energy getting the wheel to spin, it's on its own.

Now, can the wheel directly transmit power from the belt to the plane --- yes, if it is acting more brake-like than wheel-like. But it is not in the ordinary concept of a wheel that we think of it trying to inhibit motion rather than facilitate it.
gmilam
QUOTE (Derek1148+Sep 27 2007, 03:00 PM)
I don’t believe the forces involved would be in direct opposition to each other. The plane is being pushed through the air not driven by the wheels.

I'm with you on this one... However, some people are claiming that if the conveyor belt was to go fast enough it may be able to counteract the thrust of the engines. (I believe someone arrived at the conclusion that somewhere around the speed of sound might do it. )

I think that if you maintained traction between the tires and the conveyor, it might be possible - in theory. But I suspect what would happen is that the tires would lose traction and the plane would drag it's smoking wheels along the surface of the conveyor belt.

But I personally don't have the math knowledge to work it all out
Derek1148
QUOTE (NoCleverName+Sep 27 2007, 08:27 PM)
The wheels clearly have the ability to do work as they can have kinetic energy and this energy can be applied as a force over distance = work. Now, granted that most of the time we are doing work against the wheel to give it rotational kinetic energy, but once its got it, it can do work.

But let me reiterate the wheel can only do as much work as it has kinetic energy so once the "switch is turned off" to the supply of energy getting the wheel to spin, it's on its own.

Now, can the wheel directly transmit power from the belt to the plane --- yes,  if it is acting more brake-like than wheel-like. But it is not in the ordinary concept of a wheel that we think of it trying to  inhibit motion rather than facilitate it.

The wheels on a plane simply reduce friction. In the same manner than that skis on a plane reduce friction. Neither produces forward thrust. So the forces involved with the conveyor and the plane’s propulsion system are not in direct opposition with each other.
NoCleverName
There are many muddled concepts that have been at play here. Let's kick over at least one of them and that is the wheel can "absorb power from the belt and apply it to the plane". This is true, but usually the attempt is then made to state that the wheel can absorb "unlimited power" from the belt and can apply it to the plane. This is false.

The wheel exhibits resistance to turning from all the factors previously mentioned (moment of inertia, CRR, hysterisis losses, etc.). Some, but not all of these forces will be transmitted directly to the plane via the chain of torques represented by the wheel, the bearings, the struts, etc. Much of the power going into the wheel is dissipated as heat. In a properly designed wheel (with the brakes off) very little force makes its way to the plane.

Let's say it takes 10HP to get a wheel moving at 60mph. If we hook up a 100HP engine to the belt and limit the wheel speed again to 60mph, the wheel still has used 10HP. The added 90HP doesn't do anything. Now, we could use the extra 90HP to make the wheel go faster, or we could slam on the wheel's brakes and use the extra 90HP to get whatever speed we could out of the wheel. But failing all that, if it only takes 10HP to go at 60mph, that's all it'll ever take.

But, brakes on or off, big engine or small, let's note that the energy in the wheel is dependent only on it's moment of inertia and how fast it's spinning. The wheel can't act as some "power sump" by using a bigger engine to drive it. No matter the engine size, if the spin rate is the same, the inherant energy in the wheel is the same.

In general, most naysayers have attempted to make the wheel act more "brake-like" with increasing rotation speed. If you could "apply the brakes" by making the wheel significantly harder to spin the faster it was already spinning, you'd have a point. However, the key word here is significantly harder and there has been nothing but arm-waving on that score. The fact is, if the wheel acts like a "brake" and can slow the plane, it also acts as a "brake" and slows the belt, too. In essence, it's a horsepower war after that. Who's ever got the ponies wins.
NoCleverName
QUOTE (Derek1148+Sep 27 2007, 09:34 PM)
The wheels on a plane simply reduce friction.

I am wondering if you understand the concept of mechanical Work. The wheels have friction, as you note. Friction is a force. This force of friction works over a distance (be it linear or angular). By definition, Force x Distance equals Work. As long as there is a Force and it acts over a Distance, Work is performed.

In turn, Work uses up an object's store of Energy. The rate at which that Energy store is used up is Power.
Derek1148
QUOTE (NoCleverName+Sep 27 2007, 09:43 PM)
I am wondering if you understand the concept of mechanical Work.

Hey NoCleverName,

That sounds suspiciously like an insult.

I don’t believe that the wheels on a plane perform “work” during the take-off process. The reduction of friction is a function.

However, I don’t claim to be an expert in engineering. So for the time being I’ll accept your explanation.

Derek
NoCleverName
QUOTE (Derek1148+Sep 27 2007, 09:52 PM)
I don’t believe that the wheels on a plane perform “work” during the take-off process. The reduction of friction is a function.

No, without the belt in the picture, they don't. The plane performs work against them. They offer resistance (force) over an angular distance.

But, there are those who claim that, as an intermediary, the wheels serve to allow the belt to work against the plane. But, in fact, the belt works against the wheel; i.e., it causes it to move. The wheel spun by the belt does not cause the plane to move (that's the whole point of the problem!) therefore it doesn't do any work and it doesn't "transmit" any force from the belt.

The only real question is whether the belt's spinning of the wheels causes the resistance offered by the wheels to the plane to be significant. This starts to enter a fantasy land of wild extensions to reality, etc., to which thre is no end and no resolution. Suffice it to say in the "real world" a "real wheel" properly engineered would have no trouble with the belt.

As far as the wheel "working" on the plane, that would happen only if the plane were tethered in position and the power cut to the belt --- the "spin down" would attempt to perform work on the plane using the rotational K.E. of the wheel (and the belt, too, I suppose). All the energy gets spent as heat and no motion results.
Atl5p
QUOTE (egnorant+Sep 27 2007, 12:52 PM)
The belt has no influence on the plane in the original question.
It is clear that all the belt does in match the speed of the plane!
That means it is equal to the speed of the plane.
There is nothing that points anyone to believe that the belt alters, increases, decreases or has any effect on the speed of the plane.

By your use of the word silly it appear that you believe this to be the incorrect
answer. Unless you wish us to believe you are silly and correct.
No need to understand the effort involved at all.
Use 2 planes..one fully loaded and one empty and have them match speed.
Is the heavier one slower at 30 mph because it takes more effort to be at 30 mph?
(Hint....NO)

And you seem to like this for the answer.
The application of the relationships described here would prevent the plane from having any airspeed. No need to understand the forces at all.
Any force that is applied that releases the plane from 0 airspeed would violate this GIVEN situation.

Yet you have no problem determining the speed of the belt correctly despite a similar lack of specific reference.
Then you take one of your self declared unspecified methods and declare it correct while another unspecified method is incorrect.
For the "unspecified" argument to be valid you must declare that both the above versions are incorrect...for the same reason.

Just as friction has no place in the solution.

30(plane)=30(belt)
Should something else alter the speed of one, the other changes also.
29=29
No doubt that there are forces that are needed to produce the 30 in the first place, but we only need to know the result.

No, it isn't the purpose.
That is a related side effect that you have adopted.

Not many, not many at all.

It is disheartening to see some misinterpret the original question and force the plane to remain motionless.
At least my boat floats.

Bruce

egnorant...you specifically are in tune with the physical forces and facts.

You understand better than most, that a treadbelt IS CAPABLE of preventing a plane from having airspeed.

However, for THIS OP, you continue to claim that the plane's speed is related to airspeed.

That's fine. That is YOUR inturpretation of a non-specific speed determination in the OP. According to YOUR inturpretation, I DO support your finding that most any plane would still be able to take off. We've agreed on this point for about 1 year now.

I suppose however, that I will NEVER understand why anyone would put a vehicle on a moving treadbelt, and they attempt to measure it's speed by anything BUT the surface of that treadbelt. However you continue to do so.

As far as things go between you and I egnorant, I believe things are quite settled and have been quite settled for quite some time now.

I believe YOUR version would have the plane fly.

You believe MY version would have the plane at 0 IAS....however you think MY version is WRONG....while I freely extend to you to believe whatever version you wish...however silly.

In short, there is no real purpose in you continuing to communicate to me the following lines (or lines like them):

QUOTE
The belt has no influence on the plane in the original question.

That means it is equal to the speed of the plane.

No need to understand the effort involved at all.

Is the heavier one slower at 30 mph because it takes more effort to be at 30 mph?
(Hint....NO)

Yet you have no problem determining the speed of the belt correctly despite a similar lack of specific reference.

In fact, I believe the spirit of the OP is to determine if people are able to comprehend the fact that an 'airpropelled wheeled vehicle' can be influenced by various speeds inflicted upon the tires.
Egnorant YOU are one of those who DOES realize this relationship. However MANY MANY of your counterparts in the 'FlyBoy' camp do NOT realize this inter-relationship.

I wonder....why have you not made any serious efforts with these people from YOUR side? Why must it always be against ME and my (yet to be proven inaccurate) version of the OP.

Again...YOUR version is silly...that's from me...

But according to YOU, MY version is "wrong".

I can have a 'silly' opinion without having to PROVE that your version is wrong.

However, YOU CANNOT claim defacto BS on my version, because you CANT PROVE it's incorrect inturpretation...now CAN you?

Atl5p
QUOTE (NoCleverName+Sep 27 2007, 01:26 PM)
That is an important point; the problem implicitly states the belt has no influence on the plane. The fact that the belt "matches the plane's speed" indicates the belt made no effort whatsoever to prevent the plane from reaching a speed (however measured) in the first place. There is nothing in the problem that states the belt will later take on an entirely different characteristic and try to hold the plane back. There is no reason to believe the belt will act any differently in the future than it did in the past --- when it didn't restrain the plane.

The fact is, the problem states nothing about the belt other than it "matches speed." Any characteristics beyond that are inventions that exceed the problem specification.

QUOTE
That is an important point; the problem implicitly states the belt has no influence on the plane. The fact that the belt "matches the plane's speed" indicates the belt made no effort whatsoever to prevent the plane from reaching a speed (however measured) in the first place.

***?!?

WhTheF?

Point by point:
QUOTE (->
 QUOTE That is an important point; the problem implicitly states the belt has no influence on the plane. The fact that the belt "matches the plane's speed" indicates the belt made no effort whatsoever to prevent the plane from reaching a speed (however measured) in the first place.

***?!?

WhTheF?

Point by point:
problem implicitly states the belt has no influence on the plane.

Ok, FlyBoy...please 'quote' this passage verbatum from the OP....oh wait, it's NOT THERE!

In FACT, the OP is ASKING us if the treadbelt has any influnce on the plane....I really can't see how you are failing to grasp that.

Wheelspeed or Earthspeed...whatever version you choose..the question is ASKING us if the treadbelt is influencing the plane....it is NOT IMPLICITLY STATING that it DOSN"T!!!! Hoooooleeee SheeeeeAttttt!!!!

QUOTE
The fact that the belt "matches the plane's speed" indicates the belt made no effort whatsoever to prevent the plane from reaching a speed

Matches the planes speed in the OPPOSITE DIRECTION!!! It is CLEAR that....even EITHER speed relation....the belt is making SOME OPPOSING ATTEMPT or EFFORT directed TOWARDS the plane.....sheeeeesh!!

When a treadbelt matches my running speed, it holds me back....that is the result...it IS THE CHARACTERISTIC OF A TREABELT TO HOLD THINGS BACK!!!!

Where are you getting your stuff from??? I think it's been stepped on too much!
Atl5p
QUOTE (gmilam+Sep 27 2007, 03:41 PM)
I'm with you on this one... However, some people are claiming that if the conveyor belt was to go fast enough it may be able to counteract the thrust of the engines. (I believe someone arrived at the conclusion that somewhere around the speed of sound might do it. )

I think that if you maintained traction between the tires and the conveyor, it might be possible - in theory. But I suspect what would happen is that the tires would lose traction and the plane would drag it's smoking wheels along the surface of the conveyor belt.

But I personally don't have the math knowledge to work it all out

OK....the land speed record was set by a Jet Car.

The jet did the propulsion.

The wheels spun round and round...all the way to break the sound barrier....

The tires did NOT "loose traction and the Jet Car drag it's smoking wheels along the surface of the Bonneville Salt Flats."

C'mooonnnnnn!!! Wheels and tires will go just as fast as you spin them.

Now, if you took a flying jet car at 600mph, with it's wheels at 0 mph (not spinning), and then LAND the jetcar at 600mph, and thereby force the tires to go from 0-600mph in an instant....then YES in THAT situation there would be a moment of 'skidding' and 'loss of traction' while the tires spin up to speed.

However, if you are going 50 and speed up to 100, the non-driven wheels do NOT spin out.

Same for going 100-200....the wheels just spin faster

Same from 200-599...the wheels just spin faster...

BUT! What happens when the wheels go from 599 to 600mph? Oh, well, they just spin faster there too...they do NOT 'spin out'.
Atl5p
QUOTE (gmilam+Sep 27 2007, 03:41 PM)
I'm with you on this one... However, some people are claiming that if the conveyor belt was to go fast enough it may be able to counteract the thrust of the engines. (I believe someone arrived at the conclusion that somewhere around the speed of sound might do it. )

I think that if you maintained traction between the tires and the conveyor, it might be possible - in theory. But I suspect what would happen is that the tires would lose traction and the plane would drag it's smoking wheels along the surface of the conveyor belt.

But I personally don't have the math knowledge to work it all out

also from Derick:
QUOTE
I don’t believe the forces involved would be in direct opposition to each other. The plane is being pushed through the air not driven by the wheels.

Atl5p
QUOTE (NoCleverName+Sep 27 2007, 05:33 PM)
No, without the belt in the picture, they don't. The plane performs work against them. They offer resistance (force) over an angular distance.

But, there are those who claim that, as an intermediary, the wheels serve to allow the belt to work against the plane. But, in fact, the belt works against the wheel; i.e., it causes it to move. The wheel spun by the belt does not cause the plane to move (that's the whole point of the problem!) therefore it doesn't do any work and it doesn't "transmit" any force from the belt.

The only real question is whether the belt's spinning of the wheels causes the resistance offered by the wheels to the plane to be significant. This starts to enter a fantasy land of wild extensions to reality, etc., to which thre is no end and no resolution. Suffice it to say in the "real world" a "real wheel" properly engineered would have no trouble with the belt.

As far as the wheel "working" on the plane, that would happen only if the plane were tethered in position and the power cut to the belt --- the "spin down" would attempt to perform work on the plane using the rotational K.E. of the wheel (and the belt, too, I suppose). All the energy gets spent as heat and no motion results.

QUOTE
The wheel spun by the belt  does not cause the plane to move (that's the whole point of the problem!) therefore it doesn't do any work and it doesn't "transmit" any force from the belt.

Ok FlyBoy....time to belly up.

Take a toy car and a real treadbelt speed max.

Put the toy car and HOLD it down on the treadbelt. The tires will spin as fast as the treadbelt is spinning.

Now...if YOUR ABOVE STATEMENT WERE TRUE....you could LET GO of the car and it would STAY PUT in space.

However, when I perform this experiment in REALITY, the car IS DRAGGED BACKWARDS by the belt. The motion starts off slow at first, and then gets faster.

Thus the whole theory behind the following:

Put a wagon full of bricks on a treadbelt, and attach a rope from the wagon to a scale.

Set the speed at 3mph...take a reading from the scale (X)

Now set the speed at 10mph...take a reading from the scale....the reading is NOW Greater than the original "X".

Are you somehow disputing this? You don't think that forces increase when the speed is increased in this situation?

You need to have a serious PM conversation with egnorant....this is a FALSE FALSE FALSE belief!
Derek1148
gmilam
QUOTE (Atl5p+Sep 28 2007, 01:01 PM)
OK....the land speed record was set by a Jet Car.

The jet did the propulsion.

The wheels spun round and round...all the way to break the sound barrier....

The tires did NOT "loose traction and the Jet Car drag it's smoking wheels along the surface of the Bonneville Salt Flats."

Once you figure out how to drag the salt flats in the opposite direction at the same speed, then this might be relevant to the conversation.
Trippy
QUOTE (Atl5p+Sep 29 2007, 06:01 AM)
OK....the land speed record was set by a Jet Car.

The jet did the propulsion.

The wheels spun round and round...all the way to break the sound barrier....

The tires did NOT "loose traction and the Jet Car drag it's smoking wheels along the surface of the Bonneville Salt Flats."

You keep bleating on about this, but what you fail to realise is that those wheels are solid disks of aluminium, because rubber doesn't have the tensile stength to withstand it's own inertia (what some people foolishly refer to as centrifugal force), and they also have no steering control because the gyroscopic forces involved would be sufficient to flip the vehicle.
NoCleverName
QUOTE (Derek1148+Sep 28 2007, 06:26 PM)
Plane

It appears this little kid has more than enough inate smarts.

Case closed.
Bloy
QUOTE
By Atl5p
I suppose however, that I will NEVER understand why anyone would put a vehicle on a moving treadbelt, and they attempt to measure it's speed by anything BUT the surface of that treadbelt. However you continue to do so.

why? Well or starters...
To test some component of the plane that would be difficult oherwise.

...same reason a vehicle is placed on a dynamometer. to test ...

This doesn't mean that anyone actually thinks that the vehicle is actually undergoing the conditions experienced in actual movement.

Well, Atl5p apparently does.
meBigGuy
@Alt5p

Just for us dummies who cannot follow your sporadic, constantly changing train of thought, could you please elaborate (briefly) just what your point is, and whether it in any way relates to the problem.

I realize that may be asking a lot.

Trippy
QUOTE (Derek1148+Sep 29 2007, 06:26 AM)
Plane

I've posted that video on another forum for this very debate in the past.

Proof that ATL5P is NOT smarter then a 10 year old.
mggb2001
Wow!!!
I can't believe that people are still debating this.

Even though I disagree with you, Atl5p, I must commend you for wasting the hours and hours ( probably in terms of days now ) of your life defending your conclusion.

Peace,
mggb2001
meBigGuy
@mggb_2001

Actually, we are long since through debating the actual problem. Right now Alt5p seems to be concerned with the ratio of vowels to consonants in the original problem after translation into french. Depending of the birth region of the translator, there seems to be some vernacular biases that upset his apple cart.

oui-oui?

egnorant
QUOTE (Atl5p+Sep 28 2007, 05:44 PM)
You understand better than most, that a treadbelt IS CAPABLE of preventing a plane from having airspeed.

I stated that a treadbelt MIGHT be capable of preventing a plane from having airspeed.
The conditions for this to happen would be very specific and unusual.
But this has no bearing on the question asked.

QUOTE
However, for THIS OP, you continue to claim that the plane's speed is related to airspeed.
That's fine.  That is YOUR inturpretation of a non-specific speed determination in the OP.  According to YOUR inturpretation, I DO support your finding that most any plane would still be able to take off.  We've agreed on this point for about 1 year now.

I can use airspeed in this problem because the air remains with a speed of 0 mph.
The ground also has a speed of 0 mph.
Within the framework of the question anything that maintains a static relationship with the ground or air will share this speed of 0 mph.

It helps that the start of the question has the plane and belt sharing this static relationship that is a speed of 0 mph.

QUOTE (->
 QUOTE However, for THIS OP, you continue to claim that the plane's speed is related to airspeed.That's fine.  That is YOUR inturpretation of a non-specific speed determination in the OP.  According to YOUR inturpretation, I DO support your finding that most any plane would still be able to take off.  We've agreed on this point for about 1 year now.

I can use airspeed in this problem because the air remains with a speed of 0 mph.
The ground also has a speed of 0 mph.
Within the framework of the question anything that maintains a static relationship with the ground or air will share this speed of 0 mph.

It helps that the start of the question has the plane and belt sharing this static relationship that is a speed of 0 mph.

I suppose however, that I will NEVER understand why anyone would put a vehicle on a moving treadbelt, and they attempt to measure it's speed by anything BUT the surface of that treadbelt.  However you continue to do so.

Come on! Don't give up hope...you will get it someday.
We'll keep trying.

QUOTE
I believe YOUR version would have the plane fly.

That is a good start.

QUOTE (->
 QUOTE I believe YOUR version would have the plane fly.

That is a good start.

You believe MY version would have the plane at 0 IAS....however you think MY version is WRONG....while I freely extend to you to believe whatever version you wish...however silly.

Yes I do believe that your version is wrong.
And my version is correct....but silly?
In what way?

QUOTE
In short, there is no real purpose in you continuing to communicate to me the following lines (or lines like them):

Please point out the errors you see in those statements and I will examine the validity of your claims.

QUOTE (->
 QUOTE In short, there is no real purpose in you continuing to communicate to me the following lines (or lines like them):

Please point out the errors you see in those statements and I will examine the validity of your claims.

The belt has no influence on the plane in the original question.

That means it is equal to the speed of the plane.

No need to understand the effort involved at all.

Is the heavier one slower at 30 mph because it takes more effort to be at 30 mph?
(Hint....NO)

Yet you have no problem determining the speed of the belt correctly despite a similar lack of specific reference.

QUOTE
In fact, I believe the spirit of the OP is to determine if people are able to comprehend the fact that an 'airpropelled wheeled vehicle' can be influenced by various speeds inflicted upon the tires.

While that is a good question that has been answered, it is hard to make it fit the question as presented.
The question is worded in such a way that it can confuse the reader into skewing the definition of move within the presented framework.

QUOTE (->
 QUOTE In fact, I believe the spirit of the OP is to determine if people are able to comprehend the fact that an 'airpropelled wheeled vehicle' can be influenced by various speeds inflicted upon the tires.

While that is a good question that has been answered, it is hard to make it fit the question as presented.
The question is worded in such a way that it can confuse the reader into skewing the definition of move within the presented framework.

You understand better than most, that a treadbelt IS CAPABLE of preventing a plane from having airspeed.
I wonder....why have you not made any serious efforts with these people from YOUR side? Why must it always be against ME and my (yet to be proven inaccurate) version of the OP.

The basis of our disagreement is this:
You claim that the only valid method of measuring the planes speed is in relation to the surface of the belt...no matter what the movement of the belt may be.
I realize that this is true only if the belt is not moving.

My version is well presented earlier in this post.

Even you get it right on occasion.

QUOTE
However, when I perform this experiment in REALITY, the car IS DRAGGED BACKWARDS by the belt. The motion starts off slow at first, and then gets faster.

The car move faster backwards as the wheels slow to a stop.
Then the car is moving backwards at the same speed as the belt.
While it has no movement relative to the belt.
The car accelerates (gets faster) as the wheels spin slower....
Sounds right to me! but it doesn't fit your speed in relation to the belt delusion.

Bruce

Bloy
QUOTE (mggb2001+Sep 28 2007, 08:29 PM)
Wow!!!
I can't believe that people are still debating this.

Even though I disagree with you, Atl5p, I must commend you for wasting the hours and hours ( probably in terms of days now ) of your life defending your conclusion.

Peace,
mggb2001

It's just entertainment!
Atl5p has no other venue for his "show".

We oblige him just to see what scene (scheme) he will present next.
Spiff
QUOTE (Atl5p+Sep 28 2007, 06:11 PM)

Ok FlyBoy....time to belly up.

Take a toy car and a real treadbelt speed max.

Put the toy car and HOLD it down on the treadbelt. The tires will spin as fast as the treadbelt is spinning.

Now...if YOUR ABOVE STATEMENT WERE TRUE....you could LET GO of the car and it would STAY PUT in space.

However, when I perform this experiment in REALITY, the car IS DRAGGED BACKWARDS by the belt. The motion starts off slow at first, and then gets faster.

Using your own analogy, your hand holding the car on the treadbelt is like the engine of the plane. Regardless of how fast the treadbelt goes backwards, it takes very little effort to push the car ahead on the belt. So, as the conveyor in the original question moves backwards, the engines push the plane ahead anyway, as the force on the air is greater than the resistance due to the friction on the wheels.

GeeDee
No. But, the question itself is borderline irrelevant because the conveyor / wheels dynamic only involves "ground speed" whereas wing lift can only be achieved with sufficiently high "air speed". It is possible however, for this aircraft to take off IF the conveyor and aircraft were headed into constant wind velocities (hurricane?) greater than the aircrafts lift off air speed.
meBigGuy
Periodically I will repeat my thought experiment and treatment of friction

1. IMAGINE A PLANE SUSPENDED BY LEVITATION 3 FT OVER THE BELT.
2. CAN THAT PLANE ACHIEVE WINGED FLIGHT OVER A MOVING BELT FOR ANY REASONABLE BELT SPEED?
3. NOW, IMAGINE EXTENDING FRICTIONLESS, OR NEARLY SO, WHEELS TO THE BELT.
4. CAN THAT PLANE STILL ACHIEVE WINGED FLIGHT?

If you think the above plane cannot take off, please state, briefly, whether you answered NO to #2 or #4, and why, or describe why you think the above is not a valid description of the issues.

Again, regarding friction, unless the speed of the belt and the friction in the tire system and belt are enough to overcome the power of the engine, the plane will take off. But long before that the tire system would explode (1hp = 746 watts)

For humor, I also submit that if the belt moves fast enough, and drags enough air with it, the plane might take off even if it is stationary relative to the ground (before the wheel bearings burn out).
buttershug
I apologize for not having read every single post but ...

Anyways has anyone asked, why the wheels start to turn? With a car on a dynameter it's because power is transmitted to the axle from the engine. Now we all know that planes don't move forward because of powered wheels.

With aircraft the wheels only start to turn when the aircraft moves forward. I realize that if you held the aircraft stationary and moved the conveyor under it, the wheels would turn. BUT the question doesn't say that and the conveyor reacts to the wheels speed. Basically the question requires forward motion.

I find this problem to be similar to the all triangles are equilateral puzzle in that they both get the reader to accept a false premise. In this case that the plane does not move forward.
yor_on
" I find this problem to be similar to the all triangles are equilateral puzzle in that they both get the reader to accept a false premise. In this case that the plane does not move forward. "
Quite right, the wheels are moving, even if only in a circular motion, but what about the rest of the plane? Are the rest of the plane moving i ask.

Are the wings flapping, the engines may seem to be be roaring but...
Are they moving. Perhaps if we gave every piece of the plane its own plane? Perhaps then we could start to isolate the moving planes of the whole planes plane. Well, that's my three cents.. And yes, a hurricane would solve this, once and for all :)
Derek1148
QUOTE (yor_on+Sep 30 2007, 06:27 PM)
" I find this problem to be similar to the all triangles are equilateral puzzle in that they both get the reader to accept a false premise. In this case that the plane does not move forward. "
Quite right, the wheels are moving, even if only in a circular motion, but what about the rest of the plane? Are the rest of the plane moving i ask.

Are the wings flapping, the engines may seem to be be roaring but...
Are they moving. Perhaps if we gave every piece of the plane its own plane? Perhaps then we could start to isolate the moving planes of the whole planes plane. Well, that's my three cents.. And yes, a hurricane would solve this, once and for all

Are you questioning whether the plane would move forward or the definition of movement relative to a vehicle?
buttershug
QUOTE (yor_on+Sep 30 2007, 06:27 PM)
Quite right, the wheels are moving, even if only in a circular motion, but what about the rest of the plane? Are the rest of the plane moving i ask.

The wheels only move if the plane moves forward. The question does not state that the plane stays stationary. For the conveyor to have any affect the plane must move forward.
The question depends on the plane moving forward. Why do the "no" people keep insisting it's stationary?
Derek1148
The wheels on a plane reduce friction and allow the plane to move forward. The wheels do create movement. A plane on skis is able to move forward once forward thrust is created by the plane’s propulsion system. Even a plane on wheels with the brakes applied will move forward after the application of forward thrust, if the surface does not allow sufficent friction (such as an ice surface).
buttershug
QUOTE (Derek1148+Sep 30 2007, 07:18 PM)
The wheels on a plane reduce friction and allow the plane to move forward. The wheels do create movement. A plane on skis is able to move forward once forward thrust is created by the plane’s propulsion system. Even a plane on wheels with the brakes applied will move forward after the application of forward thrust, if the surface does not allow sufficent friction (such as an ice surface).

My point is any interpretation that says the plane is stationary is contradictory.

The difference between the question and reality is the conveyor belt.
The belt's movement depends on the planes speed.
You can define the planes speed based on a stationary object, in which case the plane moves forward with the conveyor moving in the oppostie direction(as in makes no real difference and the plane takes off).
Or you can define it based on the wheel speed, but if you do that, you need forward motion to get the wheels to move at all. Which means the plane moves forward (and consequently takes off when moving forward fast enough.)

No plane speed = no conveyor speed.

What I'm most interested in is why the "no" people keep insisting that the plane is stationary. That is after they realise that the "yes" people do understand air speed is needed for the plane to take off.
Derek1148
It is also important to understand the meaning of “movement” relative to a vehicle. The spinning of wheels and revving of engines alone is not “movement.”

Reference: Essays in Science (Albert Einstein); “The movement of a vehicle is considered in reference to the earth’s surface, that of a planet to the totality of the visible fixed stars.”
NoCleverName
QUOTE (buttershug+Sep 30 2007, 07:36 PM)
My point is any interpretation that says the plane is stationary is contradictory.

The difference between the question and reality is the conveyor belt.
The belt's movement depends on the planes speed.

If you try to understand this problem sensibly, you'll never learn to think like a troll.

Of course you are right. Plane don't move, belt don't move, OK dude? But in the troll's world we can't tell the difference between the plane moving over the belt versus the belt moving under the plane.

In the real world the answer to this conundrum is trivial: he who feels the acceleration is gathering speed. If we had no reference to the "outside world" and we were in the plane's cockpit and all of a sudden we observe the runway moving under us, we could easily tell who started the motion by if we felt the push of acceleration. Thus, it is trivial to measure "speed" and who is doing the "speeding" because a change in speed = acceleration x time.

However, in the troll's word-game word, actual physical effects are irrelevant. If you pursue this further in the thread, you must enter the troll's fantasy world.
buttershug
QUOTE (NoCleverName+Sep 30 2007, 09:16 PM)
If you try to understand this problem sensibly, you'll never learn to think like a troll.

Of course you are right. Plane don't move, belt don't move, OK dude? But in the troll's world we can't tell the difference between the plane moving over the belt versus the belt moving under the plane.

In the real world the answer to this conundrum is trivial: he who feels the acceleration is gathering speed. If we had no reference to the "outside world" and we were in the plane's cockpit and all of a sudden we observe the runway moving under us, we could easily tell who started the motion by if we felt the push of acceleration. Thus, it is trivial to measure "speed" and who is doing the "speeding" because a change in speed = acceleration x time.

However, in the troll's word-game word, actual physical effects are irrelevant. If you pursue this further in the thread, you must enter the troll's fantasy world.

I don't think they are trolls (well at least not all). I believe they are sincere in believing the plane does not move forward. That's what I thought at first but fairly quickly changed my mind. I think that almost everyone who reads it first thinks the plane stays stationary. The question is made to make people automatically think that. But some people can't get past that first assumption and question it.
That's the part that interests me.
NoCleverName
QUOTE (buttershug+Sep 30 2007, 09:38 PM)
I don't think they are trolls (well at least not all). I believe they are sincere in believing the plane does not move forward.

By the time your post count gets up to 100 or so you'll have a different opinion.
egnorant
QUOTE (buttershug+Sep 30 2007, 02:41 PM)
Anyways has anyone asked, why the wheels start to turn? With a car on a dynameter it's because power is transmitted to the axle from the engine. Now we all know that planes don't move forward because of powered wheels.

This was discussed many pages ago.
Everything hung on the word "exactly".
The minds that required that the speed of the plane be measured against the surface of the treadbelt have been silent on this.

The belt controller system must be nearly precognitive and adjust its speed to respond exactly to the planes movement over the belt.

In a purely literal application of the wheelspeed=planespeed version this is not hard.
Plane does not move through the air or over the ground and the belt does whatever it wants and the belt speed WILL equal the planes speed over the belt.

How the plane achieves this is not relevant....Just points moving in relation to other points.
This line of thought has been left out in favor of the obscure notion that the friction of the belt can hold the plane back.

QUOTE
With aircraft the wheels only start to turn when the aircraft moves forward. I realize that if you held the aircraft stationary and moved the conveyor under it, the wheels would turn.  BUT the question doesn't say that and the conveyor reacts to the wheels speed.  Basically the question requires forward motion.

So you must determine the correct application of the term "move" the the belt and the plane.
Is it correct to have the belt and plane measure its speed relative to the ground and air(and the starting point of the plane and belt)?

Or should we have the belt measure its speed this way and have the planes speed measured relative to the surface of the belt.

These are the 2 top runners...pick one..explain why.

I picked the first one...Should the question have stated that the air moves, it moves in relation to this point.

There is a thought that the speed of the items should be measured in relation to
"What it is sitting on".
Would it be correct to say that the air sitting atop this moving belt has speed?

QUOTE (->
 QUOTE With aircraft the wheels only start to turn when the aircraft moves forward. I realize that if you held the aircraft stationary and moved the conveyor under it, the wheels would turn.  BUT the question doesn't say that and the conveyor reacts to the wheels speed.  Basically the question requires forward motion.

So you must determine the correct application of the term "move" the the belt and the plane.
Is it correct to have the belt and plane measure its speed relative to the ground and air(and the starting point of the plane and belt)?

Or should we have the belt measure its speed this way and have the planes speed measured relative to the surface of the belt.

These are the 2 top runners...pick one..explain why.

I picked the first one...Should the question have stated that the air moves, it moves in relation to this point.

There is a thought that the speed of the items should be measured in relation to
"What it is sitting on".
Would it be correct to say that the air sitting atop this moving belt has speed?

I apologize for not having read every single post but ...

I pity the fool who tries...wait for the DVD.

Bruce

Derek1148
"It is not necessary to understand things in order to argue about them." (Pierre Augustin Caron De Beaumarchais)
meBigGuy
@egnoramt

The belt must measure the speed of the plane with the same reference as it measures its own speed. Otherwise, the problem would have had to state the changing points of reference. The implication, reading the problem, is that the reference point does not change.

If it measures relative to the ground, then all proceeds as the problem writer probably intended.

If it measures relative to its self, then it cannot move relative to itself and self-destucts (or freezes) in a paradoxical frenzy.

QUOTE
tracks the plane speed and tunes the speed of the conveyer to be exactly the same (but in opposite direction).

So lets say we butcher it and say the plane relative to the belt, and the belt relative to the ground. Now we have a positive feedback system. If the plane moves +teeny relative to the belt, then the belt moves -teeny relative to the ground, so the plane is now moving +2*teeny, etc. Obviously nonsense.

Ok then, the plane relative to the ground, and the belt relative to the plane.
Now the plane is moving +5, and the belt stays still since it is already -5 relative to the plane.

I don't even understand why this issue is being raised? Is it considered a serious field of enquiry? Or, just meaningless leftovers from Alt5p's nonsense?
Bloy
QUOTE
meBigGuy
Or, just meaningless leftovers from Alt5p's nonsense?

You got it!
egnorant
QUOTE (meBigGuy+Oct 2 2007, 02:57 AM)
The belt must measure the speed of the plane with the same reference as it measures its own speed.  Otherwise, the problem would have had to state the changing points of reference.  The implication, reading the problem, is that the reference point does not change.

If it measures relative to the ground, then all proceeds as the problem writer probably intended.

If it measures relative to its self, then it cannot move relative to itself and self-destructs (or freezes) in a paradoxical frenzy.

So lets say we butcher it and say the plane relative to the belt, and the belt relative to the ground.  Now we have a positive feedback system. If the plane moves +teeny relative to the belt, then the belt moves -teeny relative to the ground, so the plane is now moving +2*teeny, etc.  Obviously nonsense.

Ok then, the plane relative to the ground, and the belt relative to the plane.
Now the plane is moving +5, and the belt stays still since it is already -5 relative to the plane.

I don't even understand why this issue is being raised?  Is it considered a serious field of inquiry?  Or, just meaningless leftovers from Alt5p's nonsense?

Absolutely, A while back in an effort to understand the plane speed as measured in relation to the belt, I discovered 7 different relationships using the 2 different moving elements. I also included the ground and air as a single non-moving point.
The ones that related speed to themselves were of course tossed as unworkable. (3)
There was one that had no reference to the ground or air so I tossed it also as the answer must be related to the plane moving through the air, Yes or No.

The remaining 3 include the correct answer...plane and belt both relate speed to the ground/air.

One of the others is plane speed related to the belt and belt speed relative to the
ground/air. This seems to be the current champion of the easily fooled.

Last we have the plane speed measured relative to the ground/air and the belt speed relative to the plane. This is a great example of a normal takeoff with improper scientific measurements.

I was seriously looking for some germ of correctness in the no-fly arguments.
Aside from some literary devices (As the miles rolled by, The air screamed past etc) I discovered that these used an understood reference to the narrator or an item being described.

Other versions such as I ran 10 miles today only describe the action of the runner.
Once you include on a treadmill, you can understand that this action is not being translated into motion. It is an effort used to prevent backwards motion.

Of the MANY permutations of these references, the plane relative to the belt method has a real world glimmer of hope if and only if the belt moves relative to the ground at exactly the same time and speed as the plane rolls over the belt.

Not that the belt responds with any lag in time to the planes movement over the belt...it must be exact.
The tracking and tuning of the speed of the belt MUST take place with 0 lag or the
plane speed relative to the belt version falls apart.

But this is also a version that has effort not translated into motion..unless you
add the words "relative to the belt" to the original questions description of the plane moves in one direction.

The basis of the declaration that the plane must be measured relative to the belt is that it is correct to measure the speed of an object based solely upon what this object is sitting on.

All my searching has revealed that this is not always true.
The original question is one of the cases where this is not true.

Don't even get started on some of the definitions of "opposite directions" that were presented.

Trust that the plane speed relative to the belt has been carefully scrutinized and every attempt has been made to find a way to make it correct.
It failed every time.

Answer: Yes the plane flies! Interesting byproduct is that the wheels turn twice as fast as the speed of the plane.

Bruce

P.S. Yes, this is a serious game of Whack-A-Troll
yor_on
I do agree with the notion that the plane is moving :)
Even if in a stationary way. Perhaps we should introduce the concept of 'static relativistic movement' to explain it to them that not have seen the light, or in this case, the mighty flapping and them roaring engines?
Derek1148
QUOTE
I do agree with the notion that the plane is moving
Even if in a stationary way.

Define “stationary” movement.
the eschaton
WOW, i cant believe this. I read the first few pages and it seemed most people thought the plain would not take off. But i was encouraged when one poster kept up long enough to change his mind by saying basically, "well i thought that we were supposing that the plain would not move forward in which case it would not take off." Which is true but of course it does move forward. I think most where making the same mistake.
Atl5p
QUOTE (Spiff+Sep 29 2007, 09:46 PM)
Using your own analogy, your hand holding the car on the treadbelt is like the engine of the plane. Regardless of how fast the treadbelt goes backwards, it takes very little effort to push the car ahead on the belt. So, as the conveyor in the original question moves backwards, the engines push the plane ahead anyway, as the force on the air is greater than the resistance due to the friction on the wheels.

The whole point is this:

The as you hold the car on the treadbelt at 0 IAS, increasing the treadbelt speed DOES INCREASE the opposing force to the plane from the treadbelt via the tires. This force increases with the treadbelt speed.

However, if one measures the plane’s speed in relation to the crust of the planet earth, then by default the plane has Airspeed, and thus will probably fly. (Unless the plane is heavily loaded to near maximum, in which case the opposing force from the treadbelt may still prevent the plane from achieving ‘take off’ airspeed.

As I’ve said many many times, one CANNOT answer this question without first quantifying the term “Plane Speed”.

It’s the people who simply decry “Plane Flies” that bug me….how did they measure the plane’s speed? Tell me that first, and THEN answer the question.
Trippy
QUOTE (Atl5p+Oct 3 2007, 06:50 AM)
The whole point is this:

The as you hold the car on the treadbelt at 0 IAS, increasing the treadbelt speed DOES INCREASE the opposing force to the plane from the treadbelt via the tires. This force increases with the treadbelt speed.