A popular engineering problem

[cbrsmurf]

So here's the problem... for some reason it generates a lot of controversy and bad attitudes, so let's keep it civil ok? :cheers:

Here it is:

An airplane is sat on a massive conveyor belt/travelator type arrangement, as wide and as long as a runway. The conveyer belt is designed to exactly matches the rotation of the wheels, at any given time, in the opposite direction. Can the plane take off assuming there is no wind or other abnormal outside forces?

Discuss :D

[GPTECHMAN]

Im picturing essentially a treadmill for the plane, is that right?

[brownbrown4]

No it cant. If the Plane is traveling 150 mph in one postion it's not going to take off. There isnt a 150 mph wind creating a high pressure area pushing up under the wing and low pressure over the wing. without the wind its just fast moving static Plane.
air plane wings dont work if the plane is sitting in the tarmac. and a plane on a treadmill is technically sitting there like the other planes parked by terminal.
Oh and the engines can be at full throttle, but they dont make the plane fly ( the wings do) they just pull it forward to create the previous mentioned wind.

[r1brip]

The plane will take off for sure.

To move the plane pushes against the air which is standing still and dosent care what the ground is doing.

The plane dosent care wtf the ground is doing becuase the only thing the ground does is hold the plane up, it does not push it forward or backward because the wheels are not powered in anyway. Nothing that is in contact with the ground has anything to do with the movement of the plane.

Take a marble and put it on a piece of paper, move the paper. Does the marble stay exactly with the paper? No, it tries to stay where it was. Yes the marble is rolling, but in relation to position it tries to stay put.

[brownbrown4]

The plane will take off for sure.

To move the plane pushes against the air which is standing still and dosent care what the ground is doing.

The plane dosent care wtf the ground is doing becuase the only thing the ground does is hold the plane up, it does not push it forward or backward because the wheels are not powered in anyway. Nothing that is in contact with the ground has anything to do with the movement of the plane.

Take a marble and put it on a piece of paper, move the paper. Does the marble stay exactly with the paper? No, it tries to stay where it was. Yes the marble is rolling, but in relation to position it tries to stay put.
Your right the ground has no matter.
but without the air moving under the wing you have nothing... if you find a picture of the air flow around a wing you'll see what makes a plane fly....
I'm an aviation electronics tech. And before we get into the electronics side of planes, we must have a knowledge of every other aspect of planes/jet's/ helo's. Do you know what Pitch, Roll and Yaw are? What about horizontal and vertical stab's? we'll go simple, how about Speed breaks?

[deathblow]

The plane will not take off. As brownbrownbrownbrown said, there has to be wind passing over and under the wings to create the lift.

[Lost]

The plane will not take off. As brownbrownbrownbrown said, there has to be wind passing over and under the wings to create the lift.

Agreed. There must be air passing over the wings to create lift. The plane is being pushed forward by the engines and the conveyor belt is keeping it in place. The air over the wings is static the entire time, thus no lift.

Its kinda the same princepal of a motorcycle on a dyno. Even the engine is doing the work of 150mph, it is traveling nowhere. The engine will still overheat beacuse there is no wind to cool the radiator.

Work is being done but it is irrevalent to the forces that lift the plane / cool the engine.

[Dissident]

I say you're all wrong. The wheels won't move until the plane moves, since the jets are pushing the plane, the treadmill won't move until the plane actually moves. So, the plane will continue to speed up at a slower rate, but assuming you have enough runway, it will take off.

So, as you apply power to the engines, the plane will move forward (this would NOT be true of a car/bike, where the wheels drive it), and the faster it moves, th efaster the treadmill will move, but it will not be applying enough of a force to stop the plane from accellerating.

BUT, when it does take off, the wheels will be spinning as if the plane was travling twice as much as normal (creating some additional friction but not the right order of magnitude to make a big difference).

So, QED, yes, it will take off and have enough lift since the plane WILL move forward.

[nocontrol]

In this instance, yes. The plane will take off provided the wheels don't fall apart. If the average take off speed of a plane is 150mph, and the conveyer is moving at 150 in the opposite direction, then the wheels will be spinning at 300 mph. The plane will still be moving forward, as the engines are providing the thrust needed for the 150mph winds to go under the wings.

[cbrsmurf]

Have you guys taken into account that while a car travels by putting energy to the wheels, which pushes on ground -- an airplane puts its energy into the jets and/or propellors which pushes/pulls through the air, completely independent of the wheels?

[cbrsmurf]

I say you're all wrong. The wheels won't move until the plane moves, since the jets are pushing the plane, the treadmill won't move until the plane actually moves. So, the plane will continue to speed up at a slower rate, but assuming you have enough runway, it will take off.

So, as you apply power to the engines, the plane will move forward (this would NOT be true of a car/bike, where the wheels drive it), and the faster it moves, th efaster the treadmill will move, but it will not be applying enough of a force to stop the plane from accellerating.

BUT, when it does take off, the wheels will be spinning as if the plane was travling twice as much as normal (creating some additional friction but not the right order of magnitude to make a big difference).

So, QED, yes, it will take off and have enough lift since the plane WILL move forward.

well i agree with dissident and everyone who said it will take off :)

[Lost]

you are right. I read too much into the question thinking that the plane would not move. The problem does not say that. It says it will match tire rotation. The plane will pull itself forward. lol

[r1brip]

Your right the ground has no matter.
but without the air moving under the wing you have nothing... if you find a picture of the air flow around a wing you'll see what makes a plane fly....
I'm an aviation electronics tech. And before we get into the electronics side of planes, we must have a knowledge of every other aspect of planes/jet's/ helo's. Do you know what Pitch, Roll and Yaw are? What about horizontal and vertical stab's? we'll go simple, how about Speed breaks?

Dude, this is not an aviation question, its dynamics. I am an engineer and I know how a plane flies and I have solved problems like this before. The plane will take off, I promise :slap:

[cbrsmurf]

Dude, this is not an aviation question, its dynamics. I am an engineer and I know how a plane flies and I have solved problems like this before. The plane will take off, I promise :slap:

aren't you like, a freshman still, barry? :D :D :ninja:

[r1brip]

aren't you like, a freshman still, barry? :D :D :ninja:
:headbang:

[GPTECHMAN]

:headbang:
Dude, Ima have to go with our RESIDENT UCSDer....dem engineeeeers are smahhht:bowdown:

[cryptyk]

The original poster forgot to mention that the plane is a Harrier.

VTOL, beeyotch.

[brownbrown4]

Dude, this is not an aviation question, its dynamics. I am an engineer and I know how a plane flies and I have solved problems like this before. The plane will take off, I promise :slap:
ummmm Airplane, take off speed, wings, ... it's aviation ? :slap:
What kind of engineer are you?
I have an idea... i can ask a Pilot this week if every one dissagrees after my statement.
i've been Doing the Aviation thing for years, almost a decade now.
How about this?
On a Brittish air craft carrier they have a ramp....
On a U.S navy aircraft carrier. Why do they have Catapults instead of Conveyors?? because a conveyor doesn't work.
dont you think they would get rid of the complex steam systems, that create super pressure,push pistons and so on, to just use a easy conveyor? Oh and when a plane takes off on an aircraft carrier they MUST turn into the wind.. wonder why?
Oh yea the higher opposing wind speed is needed to create LIFT<---- the essential thing needed for flight. not speed.
how can a hang glider fly and not go to take off speed??? LIFT. LIFT LIFT LIFT is needed for flight just as much as wings are. Speed is Irrelevant !!!!

in regard to Nocontrols comment.
the conveyor is set to MATCH the wheel speed. not double it. if the wheels are going 150mph so is the conveyor.

[CjrJAM]

we'll go simple, how about Speed breaks?
I used to take speed breaks but have since gone through therapy and quit. Now I sometimes take long leisurely ones.

In regard to the plane, the darn thing will fly for sure! Believe me I know about this stuff, I stayed at a Hoiday Inn last night.

[brownbrown4]

The original poster forgot to mention that the plane is a Harrier.

VTOL, beeyotch.
or an Osprey... there are some particulars missing, im assuming it's a regular old air plane.

[r1brip]

On a Brittish air craft carrier they have a ramp....
On a U.S navy aircraft carrier. Why do they have Catapults instead of Conveyors?? because a conveyor doesn't work.


http://www.straightdope.com/columns/060203.html

[GPTECHMAN]

could this be the nail in the coffin...remember, keep it civil folks...

[cbrsmurf]

http://www.hypercycles.org/forums/attachment.php?attachmentid=11251&stc=1&d=1149053100

lmao wtf

[r1brip]

:cheers:

[brownbrown4]

:nerd: so it won't take off
because air plane tires wouldn't be able to take those speeds...:lift: :thumbsup:

[Dissident]

ummmm Airplane, take off speed, wings, ... it's aviation ? :slap:
What kind of engineer are you?
I have an idea... i can ask a Pilot this week if every one dissagrees after my statement.
i've been Doing the Aviation thing for years, almost a decade now.
How about this?
On a Brittish air craft carrier they have a ramp....
On a U.S navy aircraft carrier. Why do they have Catapults instead of Conveyors?? because a conveyor doesn't work.
dont you think they would get rid of the complex steam systems, that create super pressure,push pistons and so on, to just use a easy conveyor? Oh and when a plane takes off on an aircraft carrier they MUST turn into the wind.. wonder why?
Oh yea the higher opposing wind speed is needed to create LIFT<---- the essential thing needed for flight. not speed.
how can a hang glider fly and not go to take off speed??? LIFT. LIFT LIFT LIFT is needed for flight just as much as wings are. Speed is Irrelevant !!!!

in regard to Nocontrols comment.
the conveyor is set to MATCH the wheel speed. not double it. if the wheels are going 150mph so is the conveyor.

If you hold the plane in place on the conveyor so the plane doesn"t move (engines off) and move the conveyor like a treadmill at 150 MPH, the wheels will move at 150mph. Now, keep that speed of the conveyor the same speed, turn the engines on, the plane will start to accellerate. When the plane hits 150 mph, the wheels are traveling as the same rate that a plane going 300 mph with no conveyor would be going (or, twice as many rpm than normal).

Catapults are used because a conveyor would take up way more space (FYI THAT conveyor would have to go in the other direction) and you would never get enough grip between the belt and the plane's wheels. I can tell you all you want (well, almost ;) ) about taking off and landing on an aircraft carrier, since that is exactly what I do for a living (google x-47b), and our plane don't need no stinkin pilots (and, while some are, most pilots =/= engineers)

[Dissident]

:nerd: so it won't take off
because air plane tires wouldn't be able to take those speeds...:lift: :thumbsup:

Yes, they most likely would. Refer to previously mentioned catapult speeds...

[HeinskitZgerman]

because air plane tires wouldn't be able to take those speeds...:lift: :thumbsup:


Are you admitting to Barry that you were wrong?

[r1brip]

let me make this as simple as possible....

so brownbrown, you are on a skateboard that is on a treadmill. Speed up that treadmill to whatever speed you want but hold on to the side rails so you dont move. Now just pull yourself forward with the handrails. It will take very little effort. Your arms pulling you forward are just simulating what the engines on the plane are doing. So the engines fire up, plane goes forward, lift is created, and we have take off

[brownbrown4]

Yes, they most likely would. Refer to previously mentioned catapult speeds...
capapults only speed it up too 150 mph or so. plane tires arent meant for 300mph.

[brownbrown4]

Are you admitting to Barry that you were wrong?
Si....:rolleyes:

[brownbrown4]

let me make this as simple as possible....

so brownbrown, you are on a skateboard that is on a treadmill. Speed up that treadmill to whatever speed you want but hold on to the side rails so you dont move. Now just pull yourself forward with the handrails. It will take very little effort. Your arms pulling you forward are just simulating what the engines on the plane are doing. So the engines fire up, plane goes forward, lift is created, and we have take off
so the take off speed would have to be 300 mph( indicated in the plane and on the wheels).
understood. and i concede my argument... :cheers:
But who's this cecil guy? and what does he know?!!:nutkick:
i dont belive everything i read on the net
he did say that there would have to be other circumstances (i.e tires and bearings) to attain that Answer.

[MrCrashRR]

The conveyer belt is designed to exactly matches the rotation of the wheels, at any given time, in the opposite direction

given this is true,...it will never take off if the force vector of foward motion is canceled out and the plane will generate no lift....

now if you only looked at a real world possibility of this, and defined the treadmill as incapable of producing the oppisite vecor and only the wheelspeed,...eventually the plane could get up to take off speeds with the wheels moving at 2X

i mean it depends on how you read into it....

put it this way,...there is a way to set a plane on a belt to ensure that it dosent take off,...but im not sure the given conditions for that are stipulated

[grimfandango]

no wind (air) over wings.. no lift.. no fly...

[deathblow]

I got A's in Phys 2A - 2D at UCSD also, doesn't that mean I am smart? :rolleyes: Yeah right. I say it doesn't take off, just because beer is good, and yeah that does not makes sense.

[blndweasel]

The conveyer belt is designed to exactly matches the rotation of the wheels, at any given time, in the opposite direction

given this is true,...it will never take off if the force vector of foward motion is canceled out and the plane will generate no lift....

now if you only looked at a real world possibility of this, and defined the treadmill as incapable of producing the oppisite vecor and only the wheelspeed,...eventually the plane could get up to take off speeds with the wheels moving at 2X

i mean it depends on how you read into it....

put it this way,...there is a way to set a plane on a belt to ensure that it dosent take off,...but im not sure the given conditions for that are stipulated

The problem with your scenario is that you have a positive feedback loop. (assuming an escalator could actually do this) the escalator will continue accelerating to counteract the speed the wheels are moving at, but since there is little resistance on the wheels to keep them from spinning in relation to the plane itself, the escalator would continue to accelerate until first the tires blew apart as they passed their speed rating, and then the hubs of the wheels disintegrated. The landing gear would then crash into the escalator (still moving at incredible speed) and you'd have one giant cluster-F$#% as the plane lost attitude, and either veered off to one side of the runway, or ignited the fuel cells as a result of all the landing gear carnage causing sparks and debris.

[TreAdidas]

I say the thing takes off.

The thrust of the engines pushes air, the air pushes back on the plane, and this will propel the plane forward regardless of the ground. In order for something to move there must be an outside force pushing on it. What is the source of the push? The air behind the plane. The force comes from the air, not the ground.

But I haven't taken a physics course in my life, that's my intro to enigneering course logic. I just loaded up on chemistry then majored in business because I didn't want to do math all day.

We should add that pic barry posted a smiley though!

[Dissident]

The conveyer belt is designed to exactly matches the rotation of the wheels, at any given time, in the opposite direction

given this is true,...it will never take off if the force vector of foward motion is canceled out and the plane will generate no lift....

This would be true if the plane was propelled by its wheels.

[melonheadR6]

I got A's in Phys 2A - 2D at UCSD

:bowdown:

[peter1sp]

Ooooh...I got to this one late. To all the people who said it wouldn't take off, I agree for all your various reasons.

However, here is my $.02:

Airspeed and ground speed are two different entities. Airspeed is the measurement of a object moving through the air. Ground speed is the measurement of an object moving across another body.

So back to the original question. If there are no outside forces and we assume no coefficient of drag and the conveyor is a completely frictionless environment ( ie:It will actually meet the speed of the tires at any given point), then the forward velocity of the aircraft will remain at zero, regardless of how fast the wheels turn.

While an airplane flys due to airspeed, in order to take off it needs to accumulate groundspeed to force air over the wings. If the conveyor effectively cancels the groundspeed out, the airplane cannot takeoff without another outside force to create a forward velocity or airspeed (ie: a really big fan)

"You can run all day on a tread mill and not go anywhere"

If you want the reynolds numbers and lift coefficients to back this up, PM me and I'll gladly through a few fancy calculations your way. :evil:

But I really don't want to... hehe. Good post.

[Dissident]

then the forward velocity of the aircraft will remain at zero, regardless of how fast the wheels turn.

So if the plane doesn't move forward, then the speed of the wheels is zero. The only reason the conveyor would move is that the jets push the plane, hence creating wheel speed (and air speed). Unless the brakes are applied, the plane continues to move forward and gain speed, and hence lift.

Think of it this way. You know those people movers at the airport? Well, put your rolling luggage on one belt that is rolling towards you, say at 5 mph. This will be the plane. Now, you stay on the sidewalk (not ont he belt) and start dragging the luggage forward at 5 mph. The force you are exerting is comparable to the jets on the plane.

So, now the luggage is moving at 5 mph, it's wheels are rolling at 10 mph. Add wings to it and multiply everything by 15, and the thing will fly.

[brownbrown4]

Okay . some one buy an airplane and some one buy a giant Conveyor. i got $5 on it. screw it i'll put $20 on it.

[Pathogen]

Dude, this is not an aviation question, its dynamics. I am an engineer and I know how a plane flies and I have solved problems like this before. The plane will take off, I promise :slap:

No, in a traditional sense of flight there will be no way the plane will generate enough lift for flight. Although, you are completely forgetting about the effect of directional thrust. So given enough vertical thrust the plane will eventually fly, but I'm sure your engines of a standard passanger plane will explode into a zillion pieces before they can produce the required forces. The AV-8A Harrier used by the Marines is a perfect example. Except these engines are specifically designed for verticle takeoffs/landing (ie: the thrust properly balances the planes center of gravity).

So if the pilot is worth any ****, he will hit the verticle thrusters to the max and lift off the stupid treadmill.

-mark

[brownbrown4]

No, in a traditional sense of flight there will be no way the plane will generate enough lift for flight. Although, you are completely forgetting about the effect of directional thrust. So given enough vertical thrust the plane will eventually fly, but I'm sure your engines of a standard passanger plane will explode into a zillion pieces before they can produce the required forces. The AV-8A Harrier used by the Marines is a perfect example. Except these engines are specifically designed for verticle takeoffs/landing (ie: the thrust properly balances the planes center of gravity).

So if the pilot is worth any ****, he will hit the verticle thrusters to the max and lift off the stupid treadmill.

-mark
i explained the Lift thing but no one believes me :(

[MrCrashRR]

:bowdown:
what about 100, 130, 120, 105 ...etc....

**** i took them all

the question can be answered correctly either way depending on how you set it up,...thats why it make a great argument

[Dissident]

You guys all assume that the treadmill will slow the plane down significantly. It won't. The plane will still EASILY achieve takeoff speed relative to the ground (not relative to the conveyor) and will in fact take off. Man, seriously, this problem is not THAT hard.

[brownbrown4]

LOL, i gave up already. just ruffl'in the feathers.

[deathblow]

what about 100, 130, 120, 105 ...etc....

**** i took them all

the question can be answered correctly either way depending on how you set it up,...thats why it make a great argument


SHHH! Those are for nerds! :squid:

Real men take ECE classes ;).

[Asian Barbie]

So is this someone's UCSD homework problem or just for fun?

[deathblow]

So is this someone's UCSD homework problem or just for fun?


Just for fun. I still go with my assertion that it will not take off, with all the variables given. And here is another oversimplification. A kite will not all of a sudden start flying as any ground is moving underneath it, it will only fly when wind is there... umm, yeah, that makes sense.

[r1brip]

LOL, i gave up already. just ruffl'in the feathers.
:werd:

[MrCrashRR]

SHHH! Those are for nerds! :squid:

Real men take ECE classes ;).


one hydrogen atom says to another hydrogen atom "hey man i think i lost my electron...."


the other responds " you sure "


























responds " yeah, im positive"

[cbrsmurf]

one hydrogen atom says to another hydrogen atom "hey man i think i lost my electron...."


the other responds " you sure "


























responds " yeah, im positive"

lol

i can't believe i thought that was funny -- god i'm nerdy :nerd:

[nocontrol]

I can't believe we're still on this one...

Ok, to stir the pot even more:

If a tree fell in the woods, and no one was there to hear it, would it still make a sound?

I say NO. Because sound is in direct relationship with the reception on the other end, hence if there is no microphone, no ear, no detection system of any kind the tree would not make a sound. Sound is also left up to interpretation. Therefore, if what one would think sounded like a giant "thump", could really have been soft "plop" leading to believe that the sound of the tree falling in the woods was, in reality the bear taking a dump, bringing up another hot topic of debate. Because, as Newton proved, there was nobody there to witness said bear taking said dump, thus no one cared.

GET OFF IT! THE PLANE WILL TAKE OFF!

[CaptainCR]

I saw this problem on a few other boards and it amazes me how many people argue about it. Here are a few I found.

http://www.answers.google.com/answers/threadview?id=428718

http://boards.straightdope.com/sdmb/showthread.php?t=348452

http://www.avweb.com/news/columns/191034-1.html

There are a few good arguments as to why the plane can't take off, but...





































The Plane WILL FLY! :thumbsup:

[nyburner]

I'm not an engineer, but semantically, isn't this an trick question/problem/riddle?

If a plane propells itself via air, there should be no physical way a conveyor can match its wheel speed. Once the plane starts rolling via its jets/propellors [it will], the belt cannot match the wheels. Think about it...

If friction [on the wheel bearings, conveyor belt, etc.] was not in the equation, the plane would take off. However, the conveyor would be perpetually trying to match the wheel speed into infinity mphs.

[deathblow]

I can't believe we're still on this one...

Ok, to stir the pot even more:

If a tree fell in the woods, and no one was there to hear it, would it still make a sound?

I say NO. Because sound is in direct relationship with the reception on the other end, hence if there is no microphone, no ear, no detection system of any kind the tree would not make a sound. Sound is also left up to interpretation. Therefore, if what one would think sounded like a giant "thump", could really have been soft "plop" leading to believe that the sound of the tree falling in the woods was, in reality the bear taking a dump, bringing up another hot topic of debate. Because, as Newton proved, there was nobody there to witness said bear taking said dump, thus no one cared.

GET OFF IT! THE PLANE WILL TAKE OFF!

Actually, it does make a sound. Sound waves are generated and will propogate through the air at the speed, of sound, duh. The actual magnitude of the sound waves will decrease as it dissipates through the air, regardless of a subject being there, or not, to observe this phenomena. :silenced:

[peter1sp]

Someone needs to write myth Busters and make them do this one.

I wanna see it happen or not.











p.s. I still say it stays on the ground.:squid:

[MrCrashRR]

the way for the plane to stay grounded would be that the speed of the belt combind with the friction of the wheels would be equal to the thrust of the jets...

so either the wheels have nearly siezed berrings and the belt is moving back quite quickly, or the planes thrust is greater than that of the friction of the wheels * the speed of the plane... of the oppisite force vector is small and the plane takes off...

[Dissident]

Actually, even if you locked the wheels,t he tires would probably just shred and the thing would probably still take off.

[melonheadR6]

SHHH! Those are for nerds! :squid:

Real men take ECE classes ;).

Sadly I was an ECE major. Realized that I just couldn't stand it after a year of upper division classes... :rolleyes:

KC is kinda a physics grad so I'll leave the dynamics to him

[melonheadR6]

Actually, it does make a sound. Sound waves are generated and will propogate through the air at the speed, of sound, duh. The actual magnitude of the sound waves will decrease as it dissipates through the air, regardless of a subject being there, or not, to observe this phenomena. :silenced:


whoa... :thumbsup:

short and sweet :squid:

[brownbrown4]

it was done on a treadmill and a little plane with a rubberband prop.
it took off without a hitch. in all actuality that is a plane and the treadmill was a conveyor...

[brownbrown4]

whoa... :thumbsup:

short and sweet :squid:
the BEVER that cut the tree down would have heard it :thumbsup:

[nyburner]

Actually, even if you locked the wheels,t he tires would probably just shred and the thing would probably still take off.

yup.
the surface the aircraft is launching from should have no real coorelation w/ its propulsion via the air. in other words, if a plane was already moving on a runway at 50mph, then rode over a giant treadmill spinning at 50mph, it would not slow it down whatsoever, let alone make it "run in place".
think of a seaplane...

[MrCrashRR]

Actually, even if you locked the wheels,t he tires would probably just shred and the thing would probably still take off.


most likely,..you would have to counter a large ammount for thrust through them,....not the most likely thing to happen... if at all possible,...

just stating, that for the plane not to move you need to counter the foward vector,...and the only way is through the belt speed and wheel friction,...even if locked and not shreaded, the belt speed with the kenitic friction of the wheels would have to equal the thrust... which i would imagine would make it so the belt has to spin at an extremely high velocity

[peter1sp]

It won't take off. :nutkick:

[HeinskitZgerman]

Well, Jeff asked the wrong question anyway. The traditional scenario stipulates that the conveyor matches the speed of the airplane, not that of the wheels. I would say it's common practice (at least in low-level physics courses) that since friction isn't mentioned in the problem, nor any values given for it, we can ignore it.


The plane takes off either way, but if the the conveyor matches the speed of the airplane, then the wheels will spin at 2 times the speed of the plane. Right before the plane takes off at, say, 300 mph.....the plane is moving forward at 300mph, the conveyor is moving backward at 300mph, the wheels are going forward 600mph.

If the conveyor matches the speed of the wheels, the instant the engines pushed the plane forward 1 nano-skidaddling-flanhole-meter, the wheels and conveyor are going to tear off in a race to infite speed, with the wheels leading by the smallest fraction of a hair.

At least, that's my understanding of the physics of it all, trying to push it's way through 10 years of bong resin. :blink:

[TreAdidas]

Well, Jeff asked the wrong question anyway. The traditional scenario stipulates that the conveyor matches the speed of the airplane, not that of the wheels. I would say it's common practice (at least in low-level physics courses) that since friction isn't mentioned in the problem, nor any values given for it, we can ignore it.


The plane takes off either way, but if the the conveyor matches the speed of the airplane, then the wheels will spin at 2 times the speed of the plane. Right before the plane takes off at, say, 300 mph.....the plane is moving forward at 300mph, the conveyor is moving backward at 300mph, the wheels are going forward 600mph.

If the conveyor matches the speed of the wheels, the instant the engines pushed the plane forward 1 nano-skidaddling-flanhole-meter, the wheels and conveyor are going to tear off in a race to infite speed, with the wheels leading by the smallest fraction of a hair.

At least, that's my understanding of the physics of it all, trying to push it's way through 10 years of bong resin. :blink:

+1

We should have made this a poll.

[Asian Barbie]

If you guys really care to know the answer, maybe I should ask my dad? He's an aerospace engineer, I would assume that he covered this problem somewhere along the way...

[cbrsmurf]

Well, Jeff asked the wrong question anyway. The traditional scenario stipulates that the conveyor matches the speed of the airplane, not that of the wheels. I would say it's common practice (at least in low-level physics courses) that since friction isn't mentioned in the problem, nor any values given for it, we can ignore it.


The plane takes off either way, but if the the conveyor matches the speed of the airplane, then the wheels will spin at 2 times the speed of the plane. Right before the plane takes off at, say, 300 mph.....the plane is moving forward at 300mph, the conveyor is moving backward at 300mph, the wheels are going forward 600mph.

If the conveyor matches the speed of the wheels, the instant the engines pushed the plane forward 1 nano-skidaddling-flanhole-meter, the wheels and conveyor are going to tear off in a race to infite speed, with the wheels leading by the smallest fraction of a hair.

At least, that's my understanding of the physics of it all, trying to push it's way through 10 years of bong resin. :blink:

bill, stop joking around for once. This is a serious post, gawd.:rolleyes: You and your ridiculousness.

[cbrsmurf]

the BEVER that cut the tree down would have heard it :thumbsup:

beAver.

[deathblow]

beAver.

wubever :rolleyes:

[afrothunder]

wubever :rolleyes:
this thread frickin' RULES!!! :thumbsup: