See other Science/Tech Articles
Title: Brainteaser: There's an airplane on the runway..
Source:
Elsewhere
URL Source: http://www.someplaceelse.com
Published: Dec 1, 2005
Author: I have no idea
Post Date: 2005-12-01 01:10:02 by Jhoffa_
Keywords: Brainteaser:, airplane, runway..
Views: 792
Comments: 202
Imagine a plane is sat on the beginning of a massive conveyor belt/travelator type arrangement, as wide and as long as a runway, and intends to take off. The conveyer belt is designed to exactly match the speed of the wheels at any given time, moving in the opposite direction of rotation. There is no wind. Can the plane take off?
Post Comment Private Reply Ignore Thread
Top • Page Up • Full Thread • Page Down • Bottom/Latest
#1. To: Jhoffa_ (#0)
Hmm I'd say.. yes.. because it's about lift and whether there is wind or not there would be airflow under and over the wings?
Click to see: Making a difference in Iraq
No. The plane much reach takeoff "air speed", a certain speed of air flowing over the wings at which lift is generated by the wings. The plane must move forward, relative to the air flow over the wings. Merely rotating the wheels via the conveyer while the plane is otherwise motionless relative to the air won't get it done. Now, a wind tunnel instead of a conveyor....
(The Gospel of Jesus Christ is the only true good news)
True.. can I change my answer ?? :P
Click to see: Making a difference in Iraq
Are you sure you want to?
Dubya to the serfs: "It's Raining!"
Absolutely, with my compliments. It's how we learn. I want to be right so bad, that I'm willing to change my mind when I'm wrong :)
(The Gospel of Jesus Christ is the only true good news)
Absolutly! Right after pigs can fly.
Hey buddy! You got any spare change.
No.. LOL!! It sounded logical when I posted it.. until STARWIND showed up.. it's all his fault... :P
Click to see: Making a difference in Iraq
You'll feel better if you key his car...
Dubya to the serfs: "It's Raining!"
It can't take off .. its motionless.. my logic sucks :P
Click to see: Making a difference in Iraq
Key his car.. It will help clear your mind.. Like Yoga, only more destructive.
Dubya to the serfs: "It's Raining!"
Like Yoga, only more destructive. Hey that's more like it.. anyone else on the list? :P
Click to see: Making a difference in Iraq
I was just kidding.. but, if you see a government vehicle handy.. Well, no.. We'll just end up paying for it anyway.
Dubya to the serfs: "It's Raining!"
PS: "take off" speed is rotation speed.. Are you sure this can't be done from a conveyor?
Dubya to the serfs: "It's Raining!"
Well, no.. We'll just end up paying for it anyway. Shoot.. it was just going to get interesting :P
Click to see: Making a difference in Iraq
Are you sure this can't be done from a conveyor? Frick I don't know.. if the conveyor is the same speed as the plane then isnt it basically motionless?
Click to see: Making a difference in Iraq
I'm going to withold my observation for the moment..
Dubya to the serfs: "It's Raining!"
LOL! I was wrong. That is another way to say, the conveyor moves forward at the exact same speed of the plane, but the wheels never actually rotate. So the plane would gather speed, the conveyor keeps pace, the wheels never rotate, lift is produced as the air flows over the wings, plane takes off. See, Zipporah, you were right the first time :)
(The Gospel of Jesus Christ is the only true good news)
Anyone else notice that http://Rense.com is down?
#2. To: Jhoffa_ (#0)
#3. To: Starwind (#2)
#4. To: Zipporah (#3)
#5. To: Zipporah (#3)
True.. can I change my answer
#6. To: Jhoffa_ (#0)
Can the plane take off?
#7. To: Jhoffa_ (#4)
Are you sure you want to?
#8. To: Zipporah (#7)
#9. To: Jhoffa_ (#7)
#10. To: Zipporah (#9)
#11. To: Jhoffa_ (#10)
Key his car.. It will help clear your mind..
#12. To: Zipporah (#11)
#13. To: Zipporah (#11)
#14. To: Jhoffa_ (#12)
I was just kidding.. but, if you see a government vehicle handy..
#15. To: Jhoffa_ (#13)
PS: "take off" speed is rotation speed..
#16. To: Zipporah (#15)
#17. To: Jhoffa_, Zipporah (#4)
Are you sure you want to?
The conveyer belt is designed to exactly match the speed of the wheels at any given time, moving in the opposite direction of rotation.
#18. To: Jhoffa_ (#0)
 | So many morons, so few bullets. |
#19. To: Starwind (#17)
Well crap.. see it was your fault :P
See, Zipporah, you were right the first time :)
Click to see: Making a difference in Iraq
#20. To: TommyTheMadArtist (#18)
It's not really down. It's just cyber-traffic is moving up relative to rense and it only appears down. It hasn't actually landed.
Anyone else notice that http://Rense.com is down?
(The Gospel of Jesus Christ is the only true good news)
#21. To: Zipporah (#19)
It's a dirty, thankless job, but someone has to do it.
see it was your fault :P
(The Gospel of Jesus Christ is the only true good news)
#22. To: Jhoffa_ (#0)
Absolutely. Unlike a car, thrust is not generated through the wheels.
Can the plane take off?
The craft was manned by a crew that had been frozen to death. The heating equipment of the ship had been destroyed and the unimaginable cold of outer space had done the rest. The result was instant death for the men who were the last of the Trigans, all that were left of a once-mighty civilization, pride of the planet Elekton.
#23. To: Jhoffa_ (#0)
Yes, and it's easy to explain. Unlike a car or individual walking on slippery ice or a conveyer belt, a plane is propelled by thrust against air resistance and does not require surface friction of whatever may be under it. The plane is pushing itself against the air resistance, not the ground. Clever question.
Adolf Hitler... "What luck for rulers that men do not think." John F. Kennedy... "Those who make peaceful revolution impossible will make violent revolution inevitable."
#24. To: Starwind (#17)
I believe you misunderstand the question. "The conveyer belt is designed to exactly match the speed of the wheels at any given time, moving in the opposite direction of rotation." The wheels roll or "rotate" forward as the conveyer belt moves the "opposite direction." Try to imagine God holding the plane from moving forward and someone turns on the conveyer belt. The wheels spin, the conveyer belt moves along in the opposite direction yet, the plane is stationary. Now, God lets go and the plane, which was at full throttle, starts to push against the air and begins to move forward. It is irrelevant what the tires or the conveyer belt are doing.
"That is another way to say, the conveyor moves forward at the exact same speed of the plane, but the wheels never actually rotate."
Adolf Hitler... "What luck for rulers that men do not think." John F. Kennedy... "Those who make peaceful revolution impossible will make violent revolution inevitable."
#25. To: Zipporah (#1)
The plane would fly but, not for the reasons you imply. You left out a crucial factor. The plane must be propelled forward at a substantial speed in order to lift off the ground. Your answer seems to imply that the plane would hover like a chopper and depends only on the airflow caused by the engine. The engine propels the plane forward until sufficient airspeed is reached causing the lift factor on the wings you describe.
"Hmm I'd say.. yes.. because it's about lift and whether there is wind or not there would be airflow under and over the wings?"
Adolf Hitler... "What luck for rulers that men do not think." John F. Kennedy... "Those who make peaceful revolution impossible will make violent revolution inevitable."
#26. To: wakeup (#24)
That's actually a physical impossibility, or at least it would indicate the wheels skidding on the conveyer. The plane moves forward (under its thrust, weight resting on the wheels), but no, the wheels don't rotate because the forward motion of the conveyer (keeping pace with the accelerating plane) negates their rotation. The wheels can't be in physical contact with the conveyor moving forward while the wheels also rotate opposite - two objects in contact moving in opposite directions with shear forces - the wheels would be "peeling out" like a drag racer. But the wheels aren't driven and they don't need to rotate, since the conveyor is pacing the plane's velocity. From a standpoint of the plane developing lift on its own, yes. The wheels and conveyer were a "red herring". I missed it earlier.
The wheels roll or "rotate" forward as the conveyer belt moves the "opposite direction."
It is irrelevant what the tires or the conveyer belt are doing.
(The Gospel of Jesus Christ is the only true good news)
#27. To: Starwind (#26)
Read this again. "The conveyer belt is designed to exactly match the speed of the wheels at any given time, moving in the opposite direction of rotation." Note that the conveyer belt matches the speed of the wheels, NOT THE PLANE. The wheels roll forward and the conveyer belt moves the opposite directions. No friction, imagine a bike on a treadmill. Tires rolling one way... forward, and the treadmill going the other. Perfectly logical. Obviously, the question was designed to make you think the plane would spin it's tires in place and go nowhere, like a car on the conveyer belt would do. Cars push against the ground, planes push against the air. The answer would be too obvious if the conveyer belt moved along with the plane.
"the wheels don't rotate because the forward motion of the conveyer (keeping pace with the accelerating plane) negates their rotation."
Adolf Hitler... "What luck for rulers that men do not think." John F. Kennedy... "Those who make peaceful revolution impossible will make violent revolution inevitable."
#28. To: Jhoffa_ (#0)
Can the plane take off? When pigs fly so will that plane.
The conveyer belt is designed to exactly match the speed of the wheels at any given time, moving in the opposite direction of rotation. There is no wind.
Hey buddy! You got any spare change.
#29. To: Tauzero (#22)
Unlike a car, thrust is not generated through the wheels." Correct. The wheel and conveyer belt issue was included to confuse. The author knew most folks would think of how a car would react and not consider why planes fly.
"Can the plane take off? Absolutely.
Adolf Hitler... "What luck for rulers that men do not think." John F. Kennedy... "Those who make peaceful revolution impossible will make violent revolution inevitable."
#30. To: wakeup (#27)
The wheels have two speeds in this. A rotational speed which if in contact with the conveyor belt, must be matched and a translational velocity as the plane to which they are attached moves forward. And there are two directions. The rotational direction of the wheels at the tangential point of contact with the conveyeor (bottom of tire rotates rearward ), in which case the opposite direction of the conveyor would be forward, and consequently shear forces and 'skiding' would exist, if the wheels were driven (but they're not); and the other direction is the translational direction of the wheels (and the plane) - forward, in which case the opposite direction of the conveyor would be rearward. I 'overanalyzed and overempahsized' the rotational aspects. Oh, idunno, it made a fine red herring as-is, for me anyway :)
Note that the conveyer belt matches the speed of the wheels, NOT THE PLANE
The answer would be too obvious if the conveyer belt moved along with the plane.
(The Gospel of Jesus Christ is the only true good news)
#31. To: Starwind (#30)
You speak of a stationary tire. The question speaks of a rotating tire. You misunderstand the question. I clearly see a tire rolling on a conveyer belt. The tire rolls forward the belt moves in the opposite direction, just as a bike tire on a treadmil would behave. You're tired. We're done.
"....conveyer belt.......moving in the opposite direction of rotation..."
Adolf Hitler... "What luck for rulers that men do not think." John F. Kennedy... "Those who make peaceful revolution impossible will make violent revolution inevitable."
#32. To: Jhoffa_ (#0)
Of course! It doesn't matter what the ground is doing with respect to the wheels, because the wheels don't propel the craft down the runway. The propellor or jet engine cause the plane to move forward and they work just fine even if the ground is moving in the wrong direction. It will just cause the tires to rotate at twice the speed they would normally. Now I'm going to read the thread and see what everyone else said and whether I've missed something. hehehe
Can the plane take off?
- "Liberty is the solution of all social and economic questions." ~~Joseph A. Labadie
#33. To: Jhoffa_ (#0)
Without reading too many of the responses so far, if I understand right, at whatever speed the plane begins to move forward, the conveyer belt moves backwards. Assuming the plane is propelled forward by jet or prop engines and not through a drive transmission to the wheels (which would not be a particularly well designed aircraft), then it won't stop the plane from going airborne. The only difference it would make is that the wheels would be spinning twice as fast at the airspeed when it takes off (which I'm assuming won't cause them to blow out, causing the plane to crash).
Can the plane take off?
#34. To: Mr Nuke Buzzcut (#32)
I disagree. Forward motion is what provides the wing lift required for a plane to leave the ground. Forward motion keeps a plane aloft. All engine power would be merely transferred to the conveyor belt through the wheels and there would be no forward motion by the plane and its wings, ergo, no take off.
Why should we hear about body bags and deaths. Oh, I mean, it's not relevant. So why should I waste my beautiful mind on something like that? -- Big Mama Bush
#35. To: Jhoffa_, Starwind, Zipporah (#0)
Here's another one, a bit harder. A plane is flying and inside the plane's cabin is a fly which is flying. As we know, the wings of an aircraft are supporting the total weight of the the plane and it's contents. So... if the fly is flying inside the plane, does the weight of the fly count in the total weight of the aircraft?
#36. To: Neil McIver, Jhoffa_ (#35)
Yes, it's wings are displacing air, which exert downward force on the floor of the plane. If a shipping company charges by weight, would they have to pay you if you sent some helium? As for the original problem, is the plane stationary or moving with the conveyor belt? It would need to reach takeoff speed relative to the ground in order to ahieve flight. Even if it's moving, the conveyor belt may be moving enough air that there is insufficient lift (relative speed of air passing over/under wing), but I doubt that would be much of a factor.
And I'm optimistic. See, I think you can be realistic and optimistic at the same time. I'm optimistic we'll achieve -- I know we won't achieve if we send mixed signals. I know we're not going to achieve our objective if we send mixed signals - gwbush
#37. To: wbales (#34)
You are wrong on two counts, one of which is significant to the question. 1) Wing lift is created by the pressure differential created by the air passing over the airfoil surface - the top of which is longer, causing the air to move move swiftly than it does across the bottom. 2) The plane would have forward motion thanks to the thrust caused by the engines. The wheels are irrelevant, neutral, just along for the ride. The conveyor could be run at a speed 100 times that of the forward motion of the aircraft and all it would accomplish is making the wheels spin faster before takeoff. Forward motion and thereby wind speed would in no way be affected.
I disagree. Forward motion is what provides the wing lift required for a plane to leave the ground. Forward motion keeps a plane aloft. All engine power would be merely transferred to the conveyor belt through the wheels and there would be no forward motion by the plane and its wings, ergo, no take off.
- "Liberty is the solution of all social and economic questions." ~~Joseph A. Labadie
#38. To: Mr Nuke Buzzcut, JHoffa_ (#37)
this hurts my brain. ;)
#39. To: Jhoffa_ (#0)
I misread that earlier, the plane would be stationary, so barring a steam catapult or some other b-movie trick, no the plane would not take off. Maybe if the conveyer belt/plane is at a steep angle to the ground and the plane has enough space to pick up the required airspeed for the aerodynamics to kick in. There is no giant fan?
The conveyer belt is designed to exactly match the speed of the wheels at any given time, moving in the opposite direction of rotation. There is no wind.
And I'm optimistic. See, I think you can be realistic and optimistic at the same time. I'm optimistic we'll achieve -- I know we won't achieve if we send mixed signals. I know we're not going to achieve our objective if we send mixed signals - gwbush
#40. To: Jhoffa_ (#0)
Where's this runway at. I gotta see it.
That thy beloved may be delivered; save with thy right hand, and hear me.
#41. To: Mr Nuke Buzzcut (#37)
Not if it was sitting on a conveyor belt. When taking off, the thrust from the engines propel the plane down the runway overcoming the friction between the wheels and the runway. As speed increases and the plane attains take off speed, lift on the wings pulls the plane up off the ground. Think of running on ice--there is no traction--no friction to create forward movement despite a lot of thrust. Or think of a car wheel spinning on ice-- lots of thrust--no forward motion. In this hypothetical, increasing thrust of the engines would only translate into higher wheel and conveyor belt counter rotation. The plane would sit spinning its wheels and the conveyor belt no matter how much thrust was being produced by the engines. The plane would not move. The wheels and the conveyor belt would be doing all the moving--the work and energy of the engines being realized there. The plane would remain stationary and would not, therefore, be able to attain lift rquired for take off.
The plane would have forward motion thanks to the thrust caused by the engines.
Why should we hear about body bags and deaths. Oh, I mean, it's not relevant. So why should I waste my beautiful mind on something like that? -- Big Mama Bush
#42. To: wbales, Nuke, Jhoffa - I figured it out (#41)
The conveyer belt is magical in this exercise, it neutralizes and thrust from the jet engines by spinning the landing gear wheels. The plane wouldn't care about little spinny wheels and would shoot off into the air much as a similar plane on a concrete runway would do.
And I'm optimistic. See, I think you can be realistic and optimistic at the same time. I'm optimistic we'll achieve -- I know we won't achieve if we send mixed signals. I know we're not going to achieve our objective if we send mixed signals - gwbush
#43. To: Mr Nuke Buzzcut (#37)
Another example: Suppose I am on a treadmill going at at snails pace. I have no forward motion. There is ZERO relative wind speed on my face as I am stationary. Now, I turn the treadmill up to 1000 mph and I am running at 1000 mph with it. I still have no forward motion. I would still be stationary and there is ZERO relative wind speed on my face as I remain stationary. All the energy I am expending is between my feet and the treadmill. If I had wings in this situation, they would be useless.
Why should we hear about body bags and deaths. Oh, I mean, it's not relevant. So why should I waste my beautiful mind on something like that? -- Big Mama Bush
#44. To: wbales, hoffa (#41)
There are too many unaccounted-for factors for this to be a classic brain teaser.
Not if it was sitting on a conveyor belt. When taking off, the thrust from the engines propel the plane down the runway overcoming the friction between the wheels and the runway.
And I'm optimistic. See, I think you can be realistic and optimistic at the same time. I'm optimistic we'll achieve -- I know we won't achieve if we send mixed signals. I know we're not going to achieve our objective if we send mixed signals - gwbush
#45. To: wbales (#41)
I'm thinking of organizing a Shopping Cart Hockey League, we have millions of acres of abandoned retail around here.
And I'm optimistic. See, I think you can be realistic and optimistic at the same time. I'm optimistic we'll achieve -- I know we won't achieve if we send mixed signals. I know we're not going to achieve our objective if we send mixed signals - gwbush
#46. To: Mr Nuke Buzzcut (#37)
That is, BTW, very true ONCE AND ONLY AFTER a plane is airborne.
The plane would have forward motion thanks to the thrust caused by the engines.
Why should we hear about body bags and deaths. Oh, I mean, it's not relevant. So why should I waste my beautiful mind on something like that? -- Big Mama Bush
#47. To: Dakmar (#45)
I trust no jet engines would be involved.
I'm thinking of organizing a Shopping Cart Hockey League, we have millions of acres of abandoned retail around here.
Why should we hear about body bags and deaths. Oh, I mean, it's not relevant. So why should I waste my beautiful mind on something like that? -- Big Mama Bush
#48. To: wbales (#47)
No, but we're having a charity drive for estes rocket motors. They contain chemicals that might just save your life some day.
And I'm optimistic. See, I think you can be realistic and optimistic at the same time. I'm optimistic we'll achieve -- I know we won't achieve if we send mixed signals. I know we're not going to achieve our objective if we send mixed signals - gwbush
#49. To: wbales (#41)
If the plane is a prop, it might be able to take off. It would be an unusual plane for certain. The propeller air wash over the lifting surfaces could concievably generate enough lift to get the plane airborne, even as the plane had zero velocity. If it used a high bypass turbo fan jet for it's propulsion, as is typical for jetliners, the answer is never, assumeing there is no headwind at all. These engines are produce very little thrust, by their basic nature, until foreward velocity begins to cram air for combustion into the nacelle, where the air is slowed down, and hence increased in pressure for the first stage of the compressors to throw into the burners. When stationary, the compressors pull a vacuum in the nacelle and very little combustion can take place. Then, and only then do you get the massive thrust these engines are renowned for. BTW it is easy to tell what the design speed of a jet is. If the nacelle (Front intake of the engine) is 90 degrees to the air flow, it is a subsonic design. If the nacelle if angled, supersonic, with the angle matching the sonic shock wave angle generated by the speed of the plane. In other words, the greater the angle of the nacelle, the greater the design speed of the plane.
#50. To: tom007 (#49)
A jet would throttle up and not give a damn about what the tires were thinking.
And I'm optimistic. See, I think you can be realistic and optimistic at the same time. I'm optimistic we'll achieve -- I know we won't achieve if we send mixed signals. I know we're not going to achieve our objective if we send mixed signals - gwbush
#51. To: tom007 (#49)
Yet another reason this plane wouldn't take off--the jet fan engine.
Why should we hear about body bags and deaths. Oh, I mean, it's not relevant. So why should I waste my beautiful mind on something like that? -- Big Mama Bush
#52. To: wbales (#51)
get some bottlerockets and visit your local supermarkey, see if bottle rockets care how fast conveyer belt is turning.
And I'm optimistic. See, I think you can be realistic and optimistic at the same time. I'm optimistic we'll achieve -- I know we won't achieve if we send mixed signals. I know we're not going to achieve our objective if we send mixed signals - gwbush
#53. To: Dakmar (#50)
Yes, the engine could care less what the tires are doing, but the fan jets must have O2 to perform . At zero air intake velocity, ie. no foreward motion of the plane, the engine is starved for O2. Remember the nacelle actually slows down the air intake velocity and thus increases the air pressure so the compressor blades can get ahold of it. One of my Aerospace engineering professors stated that you could stand in front of a fighter jet and keep it from moving with your hands - but is it got a little foreward motion..... you are flying. He did not mean this literally, but was trying to demonstrate how these engines work. - they are designed to have plenty of high velocity air entering the nacelle.
#54. To: Dakmar (#52)
The bottle rockets would fly, no matter what the conveyor was doing. They are a self contained control system. The propellent contains an oxident. Thrust here is independent of external conditions.
some bottlerockets and visit
#55. To: tom007 (#53)
How would sitting on conveter belt with wheels spinning be different from idling on tarmac, they still sucking in air. I know I've been on jets that were able to utilise their engines for taxiing, don't tell me they are helpless if they come to a complete stop, I know better.
And I'm optimistic. See, I think you can be realistic and optimistic at the same time. I'm optimistic we'll achieve -- I know we won't achieve if we send mixed signals. I know we're not going to achieve our objective if we send mixed signals - gwbush
#56. To: Dakmar (#55)
They are rendered helpless if sitting on a conveyor belt. That is why so few modern airports have conveyor belt runways. And anyway, back to the question: if this plane could take off on a moving conveyor belt, we shouldn't need runways at all. Nope, runways are required for a jet to attain take off speed--that critical moment when airspeed produces enough lift to get the plane off the ground. On a conveyor belt, the plane would not move. An observer in the control tower would just be watching a stationary jet revving its engines. No forward movement = no lift = no take off.
I know I've been on jets that were able to utilise their engines for taxiing, don't tell me they are helpless if they come to a complete stop, I know better.
Why should we hear about body bags and deaths. Oh, I mean, it's not relevant. So why should I waste my beautiful mind on something like that? -- Big Mama Bush
#57. To: wbales (#56)
Bull, you should watch me take a airboat up a particularly wide escalator sometime. It's all about horsepower vs weight. Don't cheap out on landing gear too, I guess.
On a conveyor belt, the plane would not move.
And I'm optimistic. See, I think you can be realistic and optimistic at the same time. I'm optimistic we'll achieve -- I know we won't achieve if we send mixed signals. I know we're not going to achieve our objective if we send mixed signals - gwbush
#58. To: wbales (#56)
blast up those jets and unless the conveyer belt is physically restraining the airplane wheels with chains or something the airplane is gonna scoot across a scrolling hanna-barbara inspired runway like it was some sort of joke, it all makes perfect sense now.
On a conveyor belt, the plane would not move. An observer in the control tower would just be watching a stationary jet revving its engines. No forward movement = no lift = no take off.
And I'm optimistic. See, I think you can be realistic and optimistic at the same time. I'm optimistic we'll achieve -- I know we won't achieve if we send mixed signals. I know we're not going to achieve our objective if we send mixed signals - gwbush
#59. To: Dakmar (#58)
Do not--I repeat--DO NOT--try this at home.
blast up those jets and unless the conveyer belt is physically restraining the airplane wheels with chains or something the airplane is gonna scoot across a scrolling hanna-barbara inspired runway like it was some sort of joke, it all makes perfect sense now.
Why should we hear about body bags and deaths. Oh, I mean, it's not relevant. So why should I waste my beautiful mind on something like that? -- Big Mama Bush
#60. To: wbales (#59)
I should have stopped at shooting bottle rockets at grocery clerks, but what do I know?
And I'm optimistic. See, I think you can be realistic and optimistic at the same time. I'm optimistic we'll achieve -- I know we won't achieve if we send mixed signals. I know we're not going to achieve our objective if we send mixed signals - gwbush
#61. To: Jhoffa_ (#0)
In my opinion, the plane will move forward and can take off. If I'm wrong I'm going to have to think twice about the worth of a physics degree, lol. Here's my reasoning. There is a force applied by the thrust of the engines to propel the plane forward. Where is the opposite force to counter it and hold the plane motionless? There is only one possible source in this brainteaser: the wheels, or more specifically the axles the wheels are mounted on. How are the "as frictionless as we can engineer them" axles going to stop the plane from moving forward if they are allowed to freely spin? Yes, there is friction between the wheels and the ground, but where's the friction in the axles? Without that it does not matter what the wheels are doing. Without friction in the axles none of the "conveyer counter force" can be transferred to the plane. One more attempt to explain the importance of the axle. When you apply brakes in your car, in an attempt to stop, you are forcing the axle to stop spinning. Unfortunately, your wheels also get a vote. On ice, they often choose to disagree. However, if you don't apply the brakes, at least as far as going forwards is concerned, your car is on a near frictionless surface no matter what surface you are on: pavement, ice, or conveyer belts. If the axle is allowed to freely spin you can pretty much rule out the wheels. And lastly, why the conveyer belt? Just find a plane that can take off with the brakes fully applied (leaving long black skid marks until it gets airborne). Put a coyote in the cockpit, put a roadrunner at the end of the runway, and make sure the manufacturer of the engine is Acme! Beep! Beep! Hehehe :)
When prosperity comes, do not use all of it. - Confucious
The nation is prosperous on the whole, but how much prosperity is there in a hole? - Will Rogers
There are 9,000 hedge funds out there. There aren't that many smart people in the world. - Michael Driscoll, a trader at Bear Stearns & Co. in New York
Some days you just want to pull out the Bonehead Stick and beat people senseless. - mirage
#62. To: wakeup (#24)
You might want to rethink that. The key part you are overlooking is highlighted in bold. It is irrelevant what the tires or the conveyer belt are doing.
"The conveyer belt is designed to exactly match the speed of the wheels at any given time, moving in the opposite direction of rotation."
God is always good!
"It was an interesting day." - President Bush, recalling 9/11 [White House, 1/5/02]
#63. To: markm0722 (#61)
Well if there are such planes then of course it would fly, but since there aren't, it's a mute point.
Just find a plane that can take off with the brakes fully applied
God is always good!
"It was an interesting day." - President Bush, recalling 9/11 [White House, 1/5/02]
#64. To: markm0722 (#61)
Wow, you are putting a lot on the line there aren't you? I would have kept that info to myself.
If I'm wrong I'm going to have to think twice about the worth of a physics degree, lol.
God is always good!
"It was an interesting day." - President Bush, recalling 9/11 [White House, 1/5/02]
#65. To: RickyJ (#63)
Well if there are such planes then of course it would fly, but since there aren't, it's a mute point. That was the joke part of my post by the way. Hence the reference to the Wile E. Coyote and Road Runner.
Just find a plane that can take off with the brakes fully applied
When prosperity comes, do not use all of it. - Confucious
The nation is prosperous on the whole, but how much prosperity is there in a hole? - Will Rogers
There are 9,000 hedge funds out there. There aren't that many smart people in the world. - Michael Driscoll, a trader at Bear Stearns & Co. in New York
Some days you just want to pull out the Bonehead Stick and beat people senseless. - mirage
#66. To: Neil McIver (#33)
The only way the plane could take off is if it actually did move forward or up. Since the force of the engines is basically parallel with the ground then the only option is moving forward to become airborne. How does a multi-ton object become air born when it has no upward force being applied? The only way it could move forward is if it skidded down the runway and took off that way. I don't think they make planes capable of doing that, so it wouldn't take off. But if they had jet engines powerful enough and planes able to withstand the skidding, then it would take off.
Assuming the plane is propelled forward by jet or prop engines and not through a drive transmission to the wheels (which would not be a particularly well designed aircraft), then it won't stop the plane from going airborne. The only difference it would make is that the wheels would be spinning twice as fast at the airspeed when it takes off (which I'm assuming won't cause them to blow out, causing the plane to crash).
God is always good!
"It was an interesting day." - President Bush, recalling 9/11 [White House, 1/5/02]
#67. To: RickyJ (#66)
Why would it skid? The axle is freely rotating. The wheels are free to turn. The brakes aren't being applied.
The only way it could move forward is if it skidded down the runway and took off that way.
When prosperity comes, do not use all of it. - Confucious
The nation is prosperous on the whole, but how much prosperity is there in a hole? - Will Rogers
There are 9,000 hedge funds out there. There aren't that many smart people in the world. - Michael Driscoll, a trader at Bear Stearns & Co. in New York
Some days you just want to pull out the Bonehead Stick and beat people senseless. - mirage
#68. To: markm0722 (#67)
Since the conveyor belt must turn at exactly the opposite speed of the airplane wheels, and since there is nothing preventing the airplane from accelerating, I think we've discovered some form of perpetual motion, how can we patend this?
And I'm optimistic. See, I think you can be realistic and optimistic at the same time. I'm optimistic we'll achieve -- I know we won't achieve if we send mixed signals. I know we're not going to achieve our objective if we send mixed signals - gwbush
#69. To: Dakmar (#68)
A patent would be good. We can sell it to Acme. We'll need a warning label though for the coyote though, just so we don't get sued. "A conveyer belt will not counter the force of this back-mounted rocket, ESPECIALLY if wearing roller skates." Beep! Beep! ;)
Since the conveyor belt must turn at exactly the opposite speed of the airplane wheels, and since there is nothing preventing the airplane from accelerating, I think we've discovered some form of perpetual motion, how can we patend this?
When prosperity comes, do not use all of it. - Confucious
The nation is prosperous on the whole, but how much prosperity is there in a hole? - Will Rogers
There are 9,000 hedge funds out there. There aren't that many smart people in the world. - Michael Driscoll, a trader at Bear Stearns & Co. in New York
Some days you just want to pull out the Bonehead Stick and beat people senseless. - mirage
#70. To: markm0722 (#67)
The original post said nothing about the brakes not being applied.
The brakes aren't being applied.
God is always good!
"It was an interesting day." - President Bush, recalling 9/11 [White House, 1/5/02]
#71. To: Jhoffa_ (#0)
So some kid in college wants all of us to do their homework for them? Figures.
I have no idea
God is always good!
"It was an interesting day." - President Bush, recalling 9/11 [White House, 1/5/02]
#72. To: Jhoffa_ (#0)
Exactly where is this source, and more importantly, who are they?
Elsewhere
God is always good!
"It was an interesting day." - President Bush, recalling 9/11 [White House, 1/5/02]
#73. To: markm0722 (#69)
Perfect! A+ w/extra credit for the Loony Tunes reference.
"A conveyer belt will not counter the force of this back-mounted rocket, ESPECIALLY if wearing roller skates."
#74. To: RickyJ (#70)
The original post said nothing about the brakes not being applied. Perhaps the pilot made a hefty sidebet back at the terminal. That plane will takeoff over my dead body! I'll keep the brakes on! - Pilot Top Story - Passengers Felt Bumpy Takeoff, Co-Pilot Arrested for Murder over Conveyer Belt Wager (I'm just being silly, please forgive me. :))
The brakes aren't being applied.
When prosperity comes, do not use all of it. - Confucious
The nation is prosperous on the whole, but how much prosperity is there in a hole? - Will Rogers
There are 9,000 hedge funds out there. There aren't that many smart people in the world. - Michael Driscoll, a trader at Bear Stearns & Co. in New York
Some days you just want to pull out the Bonehead Stick and beat people senseless. - mirage
#75. To: RickyJ (#62)
I stand by what I have written. I have confidence in my understanding.
Adolf Hitler... "What luck for rulers that men do not think." John F. Kennedy... "Those who make peaceful revolution impossible will make violent revolution inevitable."
#76. To: Mr Nuke Buzzcut (#32)
Bingo. Give that man a happy face.
"It doesn't matter what the ground is doing with respect to the wheels, because the wheels don't propel the craft down the runway."
Adolf Hitler... "What luck for rulers that men do not think." John F. Kennedy... "Those who make peaceful revolution impossible will make violent revolution inevitable."
#77. To: wbales (#34)
What? How do you figure?
"...All engine power would be merely transferred to the conveyor belt through the wheels ..."
Adolf Hitler... "What luck for rulers that men do not think." John F. Kennedy... "Those who make peaceful revolution impossible will make violent revolution inevitable."
#78. To: Neil McIver (#35)
yep
does the weight of the fly count in the total weight of the aircraft?
Adolf Hitler... "What luck for rulers that men do not think." John F. Kennedy... "Those who make peaceful revolution impossible will make violent revolution inevitable."
#79. To: Dakmar (#36)
me too
I doubt that would be much of a factor.
Adolf Hitler... "What luck for rulers that men do not think." John F. Kennedy... "Those who make peaceful revolution impossible will make violent revolution inevitable."
#80. To: Mr Nuke Buzzcut (#37)
there it is
The plane would have forward motion thanks to the thrust caused by the engines.
Adolf Hitler... "What luck for rulers that men do not think." John F. Kennedy... "Those who make peaceful revolution impossible will make violent revolution inevitable."
#81. To: Dakmar (#39)
and, you've misread it again
I misread that earlier, the plane would be stationary
Adolf Hitler... "What luck for rulers that men do not think." John F. Kennedy... "Those who make peaceful revolution impossible will make violent revolution inevitable."
#82. To: A K A Stone (#40)
that's not near as important as the color of the plane and whether it is being hijacked
Where's this runway at.
Adolf Hitler... "What luck for rulers that men do not think." John F. Kennedy... "Those who make peaceful revolution impossible will make violent revolution inevitable."
#83. To: wbales (#41)
nope, you missed it entirely, embarrassing, very embarrassing
In this hypothetical, increasing thrust of the engines would only translate into higher wheel and conveyor belt counter rotation.
Adolf Hitler... "What luck for rulers that men do not think." John F. Kennedy... "Those who make peaceful revolution impossible will make violent revolution inevitable."
#84. To: Dakmar (#42)
and now the plane has feelings what if the plane just said, I DON'T WANT TO FLY
he plane wouldn't care about little spinny wheels and would shoot off into the air
Adolf Hitler... "What luck for rulers that men do not think." John F. Kennedy... "Those who make peaceful revolution impossible will make violent revolution inevitable."
#85. To: Dakmar (#44)
Nope. The question is complete.
There are too many unaccounted-for factors for this to be a classic brain teaser.
Adolf Hitler... "What luck for rulers that men do not think." John F. Kennedy... "Those who make peaceful revolution impossible will make violent revolution inevitable."
#86. To: wbales (#46)
wrong, thrust moves it forward and the plane lifts off once air speed is sufficient give it up, it's starting to hurt
he plane would have forward motion thanks to the thrust caused by the engines. That is, BTW, very true ONCE AND ONLY AFTER a plane is airborne.
Adolf Hitler... "What luck for rulers that men do not think." John F. Kennedy... "Those who make peaceful revolution impossible will make violent revolution inevitable."
#87. To: tom007 (#49)
wrong
if it used a high bypass turbo fan jet for it's propulsion, as is typical for jetliners, the answer is never,
Adolf Hitler... "What luck for rulers that men do not think." John F. Kennedy... "Those who make peaceful revolution impossible will make violent revolution inevitable."
#88. To: Dakmar (#50)
tires were thinking as you all know, tires don't think until they reach terminal velocity
A jet would throttle up and not give a damn about what the tires were thinking.
Adolf Hitler... "What luck for rulers that men do not think." John F. Kennedy... "Those who make peaceful revolution impossible will make violent revolution inevitable."
#89. To: Dakmar (#52)
good image, gets to the point, thanks
get some bottlerockets and visit your local supermarket
Adolf Hitler... "What luck for rulers that men do not think." John F. Kennedy... "Those who make peaceful revolution impossible will make violent revolution inevitable."
#90. To: tom007 (#53)
sad, very sad
Adolf Hitler... "What luck for rulers that men do not think." John F. Kennedy... "Those who make peaceful revolution impossible will make violent revolution inevitable."
#91. To: tom007 (#54)
oh, my God
The bottle rockets would fly, no matter what the conveyor was doing. They are a self contained control system. The propellent contains an oxident. Thrust here is independent of external conditions.
Adolf Hitler... "What luck for rulers that men do not think." John F. Kennedy... "Those who make peaceful revolution impossible will make violent revolution inevitable."
#92. To: Dakmar (#55)
nice, clean, clear
How would sitting on conveter belt with wheels spinning be different from idling on tarmac
Adolf Hitler... "What luck for rulers that men do not think." John F. Kennedy... "Those who make peaceful revolution impossible will make violent revolution inevitable."
#93. To: wbales (#56)
think of the poor souls who will agree with this
And anyway, back to the question: if this plane could take off on a moving conveyor belt, we shouldn't need runways at all.
Adolf Hitler... "What luck for rulers that men do not think." John F. Kennedy... "Those who make peaceful revolution impossible will make violent revolution inevitable."
#94. To: Dakmar (#57)
that sells, I'm with ya
watch me take a airboat up a particularly wide escalator
Adolf Hitler... "What luck for rulers that men do not think." John F. Kennedy... "Those who make peaceful revolution impossible will make violent revolution inevitable."
#95. To: Dakmar (#58)
what patience and restraint you show, I'm impressed
it all makes perfect sense
Adolf Hitler... "What luck for rulers that men do not think." John F. Kennedy... "Those who make peaceful revolution impossible will make violent revolution inevitable."
#96. To: Dakmar (#60)
I'm going back to repetition. Making fun isn't fun anymore. The plane will fly because it pushes against air in order to reach lift speed in contrast to a car which would push against the conveyer belt which never allows it to move forward. The car spins it's wheels in place and the plane moves forward. Best analogy... a bike and a bottle rocket. No matter how fast you peddle the bike the conveyer belt negates the forward motion. Yet, the bottle rock on wheels or not, is out of here.
I should have stopped at shooting bottle rockets at grocery clerks, but what do I know?
Adolf Hitler... "What luck for rulers that men do not think." John F. Kennedy... "Those who make peaceful revolution impossible will make violent revolution inevitable."
#97. To: markm0722 (#61)
I like it. You can't argue with it or... I've been keeping score and some of you folks are sad, real sad. Just goes to show you how forums are not a good place to persuade. No matter how much explanation, logic, patience and repetition of same, folks stick to their guns. Did anyone here change their mind? No progress was made. Yet, there is a correct answer to the question. The plane does fly. No doubt, absolutely a fact. It will fly. It's not a matter of opinion. It's a fact. Lesson to be learned: You may have the right to your opinion but, isn't it more important that your opinion be right? Isn't truth more important than ego? Isn't right more important than wrong? Now, let's go one more round and work towards a consensus. Their coming to take me away, ha ha
There is a force applied by the thrust of the engines to propel the plane forward. Where is the opposite force to counter it and hold the plane motionless?
Adolf Hitler... "What luck for rulers that men do not think." John F. Kennedy... "Those who make peaceful revolution impossible will make violent revolution inevitable."
#98. To: All (#97)
Forgive me. They're coming to take me away.
Adolf Hitler... "What luck for rulers that men do not think." John F. Kennedy... "Those who make peaceful revolution impossible will make violent revolution inevitable."
#99. To: wakeup (#97)
Well, we could hang a "Mission Accomplished" banner from the control tower. I'm not helping our case, am I? Sorry about that. ;)
Now, let's go one more round and work towards a consensus.
When prosperity comes, do not use all of it. - Confucious
The nation is prosperous on the whole, but how much prosperity is there in a hole? - Will Rogers
There are 9,000 hedge funds out there. There aren't that many smart people in the world. - Michael Driscoll, a trader at Bear Stearns & Co. in New York
Some days you just want to pull out the Bonehead Stick and beat people senseless. - mirage
#100. To: markm0722 (#99)
Clever. Mission Accomplished fits, though. It's a lie that will send most to another issue.
Adolf Hitler... "What luck for rulers that men do not think." John F. Kennedy... "Those who make peaceful revolution impossible will make violent revolution inevitable."
#101. To: All (#0)
Interestingly, the place I first saw this question posted did not have a answer. Actually, that's part of the reason I posted it... because there was such a debate over it. IMO, Yes.. The plane will fly. As markm0722 pointed out above, it's generating thrust. If you make 100,000lbs of thrust, where does it go? You can't destroy it, that's impossible. You're not expending it on the runway, because the wheels don't drive. You're not burning it up with friction, either.. as that's not mentioned. Perfect hypotheticals here. It's obviously going into forward motion. The wheels rotating (forcing the conveyor to match speed) is proof that the plane is indeed moving forward and regardless of what the conveyor is doing.
Dubya to the serfs: "It's Raining!"
#102. To: RickyJ, tom007, Neil McIver, markm0722, wakeup (#66)
Therein lies a problem made by many: confusion and/or equating the behavior/actions of solid fuel or liquid fuel rocket engines WITH turbofan gas turbines. Jets have the latter. Two extremely different propulsion systems-- two totally different engines.
But if they had jet engines powerful enough and planes able to withstand the skidding, then it would take off.
Why should we hear about body bags and deaths. Oh, I mean, it's not relevant. So why should I waste my beautiful mind on something like that? -- Big Mama Bush
#103. To: Jhoffa_, tom007 (#101)
The wheels rotating (forcing the conveyor to match speed) is proof that the plane is indeed transferring engine thrust to the conveyor belt while the plane remains stationary. Forward movement in a jet on the ground is created by friction between the ground and the tires. Remove that friction and no forward movement. Again, jet planes DO NOT have rocket engines. High bypass turbofans DO NOT behave like rocket engines.
The wheels rotating (forcing the conveyor to match speed) is proof that the plane is indeed moving forward and regardless of what the conveyor is doing.
Why should we hear about body bags and deaths. Oh, I mean, it's not relevant. So why should I waste my beautiful mind on something like that? -- Big Mama Bush
#104. To: wbales (#103)
But it could be a window fan, so far as that goes. It's making thrust, that's all that matters.
Again, jet planes DO NOT have rocket engines. High bypass turbofans DO NOT behave like rocket engines.
Dubya to the serfs: "It's Raining!"
#105. To: wbales (#103)
No it isn't, it is created by thrust from the jets. There are no drive motors for the wheels.
Forward movement in a jet on the ground is created by friction between the ground and the tires.
And I'm optimistic. See, I think you can be realistic and optimistic at the same time. I'm optimistic we'll achieve -- I know we won't achieve if we send mixed signals. I know we're not going to achieve our objective if we send mixed signals - gwbush
#106. To: wbales (#103)
Forward movement in a jet on the ground is impeded by friction between the ground and the tires. I does not matter in the least whether the craft in question is a jet turbine, a turbofan, a pulse jet or a rocket. Wheels or skids or any other gear that serve to support an aircraft while it approaches takeoff speed only burn up energy or momentum. They do not transmit it. They ain't no driveshaft on a 777.
Forward movement in a jet on the ground is
created by friction between the ground and the tires.
#107. To: Dakmar (#55)
Of course. Not helpless, just inefficent.
I know I've been on jets that were able to utilise their engines for taxiing, don't tell me they are helpless if they come to a complete stop, I know better.
#108. To: wakeup, wbales, jhoffa (#91)
oh, my God Adolf Hitler... "What luck for rulers that men do not think." John F. Kennedy... "Those who make peaceful revolution impossible will make violent revolution inevitable." wakeup posted on 2005-12-02 02:10:32 ET Reply Trace Private Reply Care to elaborate? Remember, we are talking about an air breathing engine here. By the way, I am using "Areospace Propulsion" by Dennis Sheppard, 1972, Cornell University, as my source.
The bottle rockets would fly, no matter what the conveyor was doing. They are a self contained control system. The propellent contains an oxident. Thrust here is independent of external conditions.
#109. To: tom007, wakeup, Jhoffa_ (#108)
I'm back to my original conclusion that the plane in this scenario could not fly since it would not be moving. If the conveyor belt is turning at exactly the same speed as the wheels, then by definition the plane is standing still and thus could not get airborn. Of course this could never happen, but that's the way the question is phrased.
And I'm optimistic. See, I think you can be realistic and optimistic at the same time. I'm optimistic we'll achieve -- I know we won't achieve if we send mixed signals. I know we're not going to achieve our objective if we send mixed signals - gwbush
#110. To: tom007 (#108)
The thrust from the engines will move the plane forward unless there is sufficient friction on the ground to offset the force. There is no indication in the question that this is the case. Thus, the plane will move forward. Assuming the wheels maintain contact with the belt and the belt is moving in the opposite direction, the rate of rotation of the wheels is a function of the speed of the plane + the speed of the belt. Therefore, there is a flaw in the assumptions because it is impossible for the conveyor belt to move as fast as the wheels once the plane starts moving forward. So perhaps, the trick answer is that the belt, in attempting to match the wheel rotation speed accelerates to infinity causing the wheels to fall off and the plane to crash.
#111. To: RickyJ (#66)
Moving forward generates the lift required to climb, of course. Since the plane is not thrusting against the belt, but against the gases being expelled by the engine, it would accelerate. On further thought, though, the only way the plane could move forward is if the wheels turned fasted than the conveyor belt, and the operation of the belt would make that impossible. Ergo, as soon as thrust was applied, both the belt and the wheels would accelerate to an infinite speed, at which time the wheels, and probably the belt would both instantly explode, killing everyone and making the question moot. At that point the question would need to be redefined.
How does a multi-ton object become air born when it has no upward force being applied? The only way it could move forward is if it skidded down the runway and took off that way.
#112. To: Soren (#110)
Ya beat me to the punch.
#113. To: Neil McIver (#112)
LOL. Amazing how similar our thought processes were.
#114. To: wbales (#41)
You are still making the incorrect assumption that an airplane moves forward the same way a car does, by turning the wheels against the ground. If I were standing on ice and had a jetpack on, it wouldn't matter if my feet couldn't get any traction. If my car had jato jets strapped to the trunk, I wouldn't even have to put it in gear to move forward. Airplane wheels don't produce thrust. They're just along for the ride.
Think of running on ice--there is no traction--no friction to create forward movement despite a lot of thrust. Or think of a car wheel spinning on ice-- lots of thrust--no forward motion.
- "Liberty is the solution of all social and economic questions." ~~Joseph A. Labadie
#115. To: wbales (#43)
Now, I turn the treadmill up to 1000 mph and I am running at 1000 mph with it. I still have no forward motion. I would still be stationary and there is ZERO relative wind speed on my face as I remain stationary. All the energy I am expending is between my feet and the treadmill. If I had wings in this situation, they would be useless. Fine. Now strap a jet engine on your back and fire it up. My guess is you'll start feeling that wind on your face as you body shoots off the treadmill like a rocket.
Suppose I am on a treadmill going at at snails pace. I have no forward motion. There is ZERO relative wind speed on my face as I am stationary.
- "Liberty is the solution of all social and economic questions." ~~Joseph A. Labadie
#116. To: wbales (#46)
You must be seeing some very rare and unique airplanes if they have drive wheels. In all my years, I've never, ever seen one. Not even on TV or in books. There might be one out there, but personally I doubt it.
That is, BTW, very true ONCE AND ONLY AFTER a plane is airborne.
- "Liberty is the solution of all social and economic questions." ~~Joseph A. Labadie
#117. To: Dakmar (#57)
If a plane can't take off on a conveyor belt, then an airboat cannot go up river.
Bull, you should watch me take a airboat up a particularly wide escalator sometime. It's all about horsepower vs weight. Don't cheap out on landing gear too, I guess.
- "Liberty is the solution of all social and economic questions." ~~Joseph A. Labadie
#118. To: RickyJ (#63)
Don't be so sure about those planes not existing. All you would need is an propulsion system that produces enough thrust to overcome the friction of non-moving landing gear. Think ski-plane. Think sea-plane.
Well if there are such planes then of course it would fly, but since there aren't, it's a mute point.
- "Liberty is the solution of all social and economic questions." ~~Joseph A. Labadie
#119. To: Dakmar (#109)
But the plane WOULD move forward. Lets break it down: 1) The plane starts at a standstill. The conveyor is not moving. 2) The pilot lays into the throttles and the plane starts to move forward due to the thrust created by those, oh so inefficient, jet engines. Let's say it moves at 1 mph. 3) The conveyor now matches by moving at 1 mph in the opposite direction. 4) Whoa! That causes the wheels to rotate at a speed equivalent to 2 mph. 5) Which in turn causes the conveyor to double its speed ... which speeds up the wheels ... which speeds up the conveyor... 6) Meanwhile the turbines are spinning up and generating more thrust which moves the plane forward a bit faster -- relative to the surrounding environment and thereby adding even more speed to the feedback loop between the tires and conveyor. 7) The only question now is how long it will take for the conveyor and wheels to reach the speed of infinite or major component failure first. 8) Gawd, I hope the plane takes off before those suckers blow up!
I'm back to my original conclusion that the plane in this scenario could not fly since it would not be moving. If the conveyor belt is turning at exactly the same speed as the wheels, then by definition the plane is standing still and thus could not get airborn. Of course this could never happen, but that's the way the question is phrased.
- "Liberty is the solution of all social and economic questions." ~~Joseph A. Labadie
#120. To: Mr Nuke Buzzcut (#119)
It doesn't say that the wheels/conveyor cannot reach infinite speed, so given the parameters of the question the plane cannot take off.
And I'm optimistic. See, I think you can be realistic and optimistic at the same time. I'm optimistic we'll achieve -- I know we won't achieve if we send mixed signals. I know we're not going to achieve our objective if we send mixed signals - gwbush
#121. To: Dakmar (#120)
There's an airplane on the runway.. I think we need to change the title to .. There's a fly in your soup .. or some other such nonsense..
Click to see: Making a difference in Iraq
#122. To: Zipporah (#121)
If I could walk that way I wouldn't need the talcum poweder.
And I'm optimistic. See, I think you can be realistic and optimistic at the same time. I'm optimistic we'll achieve -- I know we won't achieve if we send mixed signals. I know we're not going to achieve our objective if we send mixed signals - gwbush
#123. To: Dakmar (#122)
Even better! 
Click to see: Making a difference in Iraq
#124. To: wbales, RickyJ, tom007, Neil McIver, markm0722, wakeup, Dakmar, Mr Nuke Buzzcut, Soren (#102)
Therein lies a problem made by many: confusion and/or equating the behavior/actions of solid fuel or liquid fuel rocket engines WITH turbofan gas turbines. Jets have the latter. Two extremely different propulsion systems-- two totally different engines. All of these engines generate thrust. What is going to counter that thrust? If you want my opinion, the problem lies with the "skidding". What's skidding? The wheels are allowed to freely rotate. Freely rotating tires do not stop planes. In fact, they are designed to hinder the plane as little as possible. If engineers had their way they'd be frictionless (at least in the direction the plane is moving) to ease takeoff. Time for another analogy I think. Let's say I am standing on a frictionless treadmill (conveyer belt). As I try to run the treadmill slides out from under me. Each step I take merely makes the treadmill spin. I'm not going anywhere no matter how hard I try. The reason is I am using my feet (wheels) to provide forward "thrust" and all that energy is lost. It cannot be transferred to the surface I am standing on because it is frictionless. I might just as well be trying to walk on ice with while wearing icy shoes. Perhaps this is why many seem to think the plane will not move. However, now let's say I mount a fan on my back (jet engine). I turn it on. I'm standing on a frictionless treadmill. Am I going to move forward? Most definitely. A force is being applied to me. What's going to stop me from moving? What is going to counter the thrust of that fan? My feet? Not a chance. I'm standing on the equivalent of ice! I can do anything I want with my feet and it isn't going to matter. I could try running backwards in place. I could try running forwards. My feet don't matter though. The more frantic I move them the more comedic the effect as I get pushed off the front of the treadmill. And believe me, if I was a coyote and mounted Acme's jet engine on my back, I'd be trying to maximize comedic effect. ;) It does not matter how efficient or inefficient its fan is. As long as ANY force is being applied which is not countered by an opposing force the plane will accelerate. There is no opposing force to counter it. The engine is not the key to understanding this problem in my opinion, but the realization that the wheels of the plane cannot counter the thrust of the engines. As a side note, on the off chance the wheels spin infinitely fast in this brainteaser (not saying they are, wasn't needed for a solution), there is one more issue with the plane taking off. It would have perfect gyroscopes mounted (Gyroscope). It would prevent the plane from performing "yaw" and "roll". Luckily only "pitch" is needed in takeoff (Pitch, Yaw and Roll). That could definitely pose a problem on landing though. There would be no circling back to the same airport, lol.
But if they had jet engines powerful enough and planes able to withstand the skidding, then it would take off.
When prosperity comes, do not use all of it. - Confucious
The nation is prosperous on the whole, but how much prosperity is there in a hole? - Will Rogers
There are 9,000 hedge funds out there. There aren't that many smart people in the world. - Michael Driscoll, a trader at Bear Stearns & Co. in New York
Some days you just want to pull out the Bonehead Stick and beat people senseless. - mirage
#125. To: Jhoffa_ (#0)
Here's one for you. Your in a boat in a pond. You throw something overboard, it sinks. Does the level of the pond go up, go down or stay the same?
"Unthinking respect for authority is the greatest enemy of truth." - Albert Einstein
#126. To: All, lodwick, Zipporah, wbales, who knows what evil, Soda Pop, Red Jones, christine, robin, wakeup, Diana, YertleTurtle, Elliott Jackalope, TommyTheMadArtist, BTP Holdings (#125)
Pingasaurusreximusmaximus...... Yall
"Unthinking respect for authority is the greatest enemy of truth." - Albert Einstein
#127. To: timetobuildaboat (#125)
Does the level of the pond go up, go down or stay the same? This isn't a veiled analogy about the war and the presidential popularity polls is it? If not, then the pond's level stays the same. ;)
Your in a boat in a pond. You throw something overboard, it sinks.
When prosperity comes, do not use all of it. - Confucious
The nation is prosperous on the whole, but how much prosperity is there in a hole? - Will Rogers
There are 9,000 hedge funds out there. There aren't that many smart people in the world. - Michael Driscoll, a trader at Bear Stearns & Co. in New York
Some days you just want to pull out the Bonehead Stick and beat people senseless. - mirage
#128. To: markm0722 (#127)
If it IS a veiled analogy about the war and the presidential popularity polls I'd have to use the president's own words to solve it. Make the pie higher. Now we just need to figure out what that means and how it applies here. ;)
When prosperity comes, do not use all of it. - Confucious
The nation is prosperous on the whole, but how much prosperity is there in a hole? - Will Rogers
There are 9,000 hedge funds out there. There aren't that many smart people in the world. - Michael Driscoll, a trader at Bear Stearns & Co. in New York
Some days you just want to pull out the Bonehead Stick and beat people senseless. - mirage
#129. To: markm0722 (#127)
It is not a political analogy, and yet I cannot respond with a confirmation due to others who might find a need to answer.
If not, then the pond's level stays the same. ;)
"Unthinking respect for authority is the greatest enemy of truth." - Albert Einstein
#130. To: timetobuildaboat (#125)
Does the level of the pond go up, go down or stay the same? "Unthinking respect for authority is the greatest enemy of truth." - Albert Einstein I'll bite. Because what you threw sinks, it is denser than water. The boat would rise upwards enough to equal the water weight of the rock (negitive displacement?) This would cause the water in the pond to become lower. BUT, the rock's volume would cause the water level to rise. As the rock is denser than the water (it sinks), the volume of water displaced by the rock is less than the volume of water need to float the rock when it was in the boat. So the boat rises AND the level of the water is lowered. Nice question.
it sinks.
#131. To: tom007 (#130)
Ding, ding, ding.....we have a winner. The simple fact that it sinks tells you that it is denser than water and would displace more water in the boat than it does when you let it fall to the bottom where it would rest it's weight.
So the boat rises AND the level of the water is lowered.
"Thinking that women have a corner on caring is delusional" - Albert Einstein
#132. To: wbales (#103)
No it's not and no it doesn't. I can't believe I got sucked into this again.
The wheels rotating (forcing the conveyor to match speed) is proof that the plane is indeed transferring engine thrust to the conveyor belt while the plane remains stationary.
Adolf Hitler... "What luck for rulers that men do not think." John F. Kennedy... "Those who make peaceful revolution impossible will make violent revolution inevitable."
#133. To: wakeup (#132)
Somebody stop the madness.
I can't believe I got sucked into this again.
"Thinking that women have a corner on caring is delusional" - A Man not thinking with his dick
#134. To: timetobuildaboat (#125)
Does the level of the pond go up, go down or stay the same? Was what was thrown overboard lighter or heavier than water?
Your in a boat in a pond. You throw something overboard, it sinks.
And I'm optimistic. See, I think you can be realistic and optimistic at the same time. I'm optimistic we'll achieve -- I know we won't achieve if we send mixed signals. I know we're not going to achieve our objective if we send mixed signals - gwbush
#135. To: timetobuildaboat (#131)
Ding, ding, ding.....we have a winner. The simple fact that it sinks tells you that it is denser than water and would displace more water in the boat than it does when you let it fall to the bottom where it would rest it's weight. I stand corrected. I should have done the math. I got too caught up in taking a stab at political humor, lol. A 100 ton boat displaces 100 tons of water. If 99.999 tons of nearly infinite density material contained within a thimble is suddenly dumped over the side it will displace next to nothing, and neither will what's left of the boat. My bad. Well done.
So the boat rises AND the level of the water is lowered.
When prosperity comes, do not use all of it. - Confucious
The nation is prosperous on the whole, but how much prosperity is there in a hole? - Will Rogers
There are 9,000 hedge funds out there. There aren't that many smart people in the world. - Michael Driscoll, a trader at Bear Stearns & Co. in New York
Some days you just want to pull out the Bonehead Stick and beat people senseless. - mirage
#136. To: Dakmar (#134)
It sinks.....
Was what was thrown overboard lighter or heavier than water?
"Thinking that women have a corner on caring is delusional" - A Man not thinking with his dick
#137. To: randge (#106)
How can anyone think the wheels are driven by the plane engines?
They ain't no driveshaft on a 777.
Adolf Hitler... "What luck for rulers that men do not think." John F. Kennedy... "Those who make peaceful revolution impossible will make violent revolution inevitable."
#138. To: markm0722 (#135)
Imagine a boat with a chunk of a star in it weighing hundreds of tons and it's the size of a thimble and you throw it overboard......
"Thinking that women have a corner on caring is delusional" - A Man not thinking with his dick
#139. To: Dakmar (#109)
not true
If the conveyor belt is turning at exactly the same speed as the wheels, then by definition the plane is standing still...
Adolf Hitler... "What luck for rulers that men do not think." John F. Kennedy... "Those who make peaceful revolution impossible will make violent revolution inevitable."
#140. To: Soren (#110)
no trick answer, no trick question
perhaps, the trick answer is that the belt...
Adolf Hitler... "What luck for rulers that men do not think." John F. Kennedy... "Those who make peaceful revolution impossible will make violent revolution inevitable."
#141. To: wakeup (#140)
I could see it considering I'm on a copious amount of wine. All is good and all is a little fuzzy...:P
no trick answer, no trick question
"Thinking that women have a corner on caring is delusional" - A Man not thinking with his dick
#142. To: Neil McIver (#111)
nope, the wheels and conveyer belt are none issues
the only way the plane could move forward is if the wheels turned fasted than the conveyor belt
Adolf Hitler... "What luck for rulers that men do not think." John F. Kennedy... "Those who make peaceful revolution impossible will make violent revolution inevitable."
#143. To: Soren (#113)
both of you are mistaken
LOL. Amazing how similar our thought processes were.
Adolf Hitler... "What luck for rulers that men do not think." John F. Kennedy... "Those who make peaceful revolution impossible will make violent revolution inevitable."
#144. To: wakeup, wbales, markm0722 (#132)
In the real world a powerful plane would take off after wasting precious fuel and wear & tear countering a conveyor belt some idiot is running in the wrong direction. Steam catapults currently in use seem much more sensible for that task. This is why I said there isn't enough detail, like are the wheels skidding. It seems clear (to me, anyway) that we are to assume that the tires of the airplane are in perfect contact with convbelt, so once again, no, the plane could not get airborn because an unknown force is causing the conveyer belt to negate any forward motion.
And I'm optimistic. See, I think you can be realistic and optimistic at the same time. I'm optimistic we'll achieve -- I know we won't achieve if we send mixed signals. I know we're not going to achieve our objective if we send mixed signals - gwbush
#145. To: Dakmar (#109)
That is the way I see it. Also many do not realize the difference between rockets and air breathing jet engines.Understandable as some of the jargon is not strictly accurate. A jato (jet assist take off) for example is a rocket, though its name implies it is a jet.
If the conveyor belt is turning at exactly the same speed as the wheels, then by definition the plane is standing still and thus could not get airborn. Of course this could never happen, but that's the way the question is phrased.
#146. To: timetobuildaboat (#138)
I actually used a bit of a neutron star in my mental picture (give or take), so you aren't far off! ;)
Imagine a boat with a chunk of a star in it weighing hundreds of tons and it's the size of a thimble and you throw it overboard......
When prosperity comes, do not use all of it. - Confucious
The nation is prosperous on the whole, but how much prosperity is there in a hole? - Will Rogers
There are 9,000 hedge funds out there. There aren't that many smart people in the world. - Michael Driscoll, a trader at Bear Stearns & Co. in New York
Some days you just want to pull out the Bonehead Stick and beat people senseless. - mirage
#147. To: markm0722 (#146)
One of the brighter of the minions.....congratulations
"Thinking that women have a corner on caring is delusional" - A Man not thinking with his dick
#148. To: markm0722 (#146)
Actually supprised you did not go on about the conveyor/plane situatuion like many of the others. Kinda strange IMHO.
"Thinking that women have a corner on caring is delusional" - A Man not thinking with his dick
#149. To: wakeup (#142)
For the sake if this question, yes they are. It is mathematically impossible that the plane could move forward while in contact with cvbelt, the landing gear wheels are in fact solidly attached to the airframe, and are only moving forward to compensate for the rearward movement of conveyor belt. It says so right at the top! :)
nope, the wheels and conveyer belt are none issues
And I'm optimistic. See, I think you can be realistic and optimistic at the same time. I'm optimistic we'll achieve -- I know we won't achieve if we send mixed signals. I know we're not going to achieve our objective if we send mixed signals - gwbush
#150. To: Dakmar (#149)
Are you mental?
It is mathematically impossible that the plane could move forward while in contact with cvbelt,
"Thinking that women have a corner on caring is delusional" - A Man not thinking with his dick
#151. To: tom007 (#145)
For the purpose of this thread jet vs rocket doesn't matter, we have very few runways higher than 80,000 feet anyway, and only a couple of them are testing conveyor belt technology.
And I'm optimistic. See, I think you can be realistic and optimistic at the same time. I'm optimistic we'll achieve -- I know we won't achieve if we send mixed signals. I know we're not going to achieve our objective if we send mixed signals - gwbush
#152. To: All (#145)
I'm re-thinking this. Whatever thrust is produced by the engines would be applied to the mass of the plane, seems the wheels and conveyor are immaterial.
#153. To: Dakmar (#151)
The epitomy of madness or sarcasm.
we have very few runways higher than 80,000 feet anyway, and only a couple of them are testing conveyor belt technology.
"Thinking that women have a corner on caring is delusional" - A Man not thinking with his dick
#154. To: timetobuildaboat (#150)
Yeah, so what? Forget physics, in the world of this brain-teaser the cbelt has to achieve infinite speed to compensate. The wheels are spinning, they must be there...Are you mental?
And I'm optimistic. See, I think you can be realistic and optimistic at the same time. I'm optimistic we'll achieve -- I know we won't achieve if we send mixed signals. I know we're not going to achieve our objective if we send mixed signals - gwbush
#155. To: timetobuildaboat (#153)
Thank you, I was only going for honest...
The epitomy of madness or sarcasm.
And I'm optimistic. See, I think you can be realistic and optimistic at the same time. I'm optimistic we'll achieve -- I know we won't achieve if we send mixed signals. I know we're not going to achieve our objective if we send mixed signals - gwbush
#156. To: Dakmar (#154)
If you close your left eye and cycle the closing and opening of the right eye you can see Jesus....
Forget physics, in the world of this brain-teaser the cbelt has to achieve infinite speed to compensate. The wheels are spinning, they must be there...
"Thinking that women have a corner on caring is delusional" - A Man not thinking with his dick
#157. To: timetobuildaboat (#156)
You can do that with these new visual mousees to, just hold it upside down and look straight into the light...
And I'm optimistic. See, I think you can be realistic and optimistic at the same time. I'm optimistic we'll achieve -- I know we won't achieve if we send mixed signals. I know we're not going to achieve our objective if we send mixed signals - gwbush
#158. To: tom007 (#152)
I think you made it just in time. Look what I found. I'm re-thinking this. Whatever thrust is produced by the engines would be applied to the mass of the plane, seems the wheels and conveyor are immaterial.
When prosperity comes, do not use all of it. - Confucious
The nation is prosperous on the whole, but how much prosperity is there in a hole? - Will Rogers
There are 9,000 hedge funds out there. There aren't that many smart people in the world. - Michael Driscoll, a trader at Bear Stearns & Co. in New York
Some days you just want to pull out the Bonehead Stick and beat people senseless. - mirage
#159. To: Dakmar (#157)
The same can be achieved using phosphines or imprinted images on the retina via black in white images...pretty neat stuff. But that would lack meaning among those on the other side.
You can do that with these new visual mousees to, just hold it upside down and look straight into the light...
"Thinking that women have a corner on caring is delusional" - A Man not thinking with his dick
#160. To: markm0722 (#158)
EXCELLENT. Started to think of some dynamics classes - that cleared the fog.
#161. To: tom007 (#160)
It seems we are now on the same page with both brainteasers now. Whew!
EXCELLENT. Started to think of some dynamics classes - that cleared the fog.
When prosperity comes, do not use all of it. - Confucious
The nation is prosperous on the whole, but how much prosperity is there in a hole? - Will Rogers
There are 9,000 hedge funds out there. There aren't that many smart people in the world. - Michael Driscoll, a trader at Bear Stearns & Co. in New York
Some days you just want to pull out the Bonehead Stick and beat people senseless. - mirage
#162. To: Soren (#110)
Excellent analysis!
God is always good!
"It was an interesting day." - President Bush, recalling 9/11 [White House, 1/5/02]
#163. To: wakeup (#75)
The tires would burn off, then the wheels would break off, due to the massive heat generated by the race to infinite speeds brought about by the unreal exact matching of the rotational speed of the airplane wheels by the conveyer belt, before the plane had a chance to get enough speed to get airborne. The plane would then come to a skidding halt on the runway, it would not take off. I gave you an excellent clue why your hypothesis was wrong, but it seemed you were too busy calling other people’s analysis “Sad, really sad”, to notice.
I stand by what I have written. I have confidence in my understanding.
God is always good!
"It was an interesting day." - President Bush, recalling 9/11 [White House, 1/5/02]
#164. To: Neil McIver (#111)
So you read Soren's post huh? LOL! Just kidding! Good analysis, except for the exploding part, I think the wheels would break off before that happened, thus causing the conveyer belt to stop.
God is always good!
"It was an interesting day." - President Bush, recalling 9/11 [White House, 1/5/02]
#165. To: Dakmar (#149)
in a car, true in a plane, nope
For the sake if this question, yes they are. It is mathematically impossible that the plane could move forward while in contact with cvbelt, the landing gear wheels are in fact solidly attached to the airframe, and are only moving forward to compensate for the rearward movement of conveyor belt. It says so right at the top! :)
Adolf Hitler... "What luck for rulers that men do not think." John F. Kennedy... "Those who make peaceful revolution impossible will make violent revolution inevitable."
#166. To: tom007 (#152)
bingo people can change thanks God, I needed that
I'm re-thinking this. Whatever thrust is produced by the engines would be applied to the mass of the plane, seems the wheels and conveyor are immaterial.
Adolf Hitler... "What luck for rulers that men do not think." John F. Kennedy... "Those who make peaceful revolution impossible will make violent revolution inevitable."
#167. To: timetobuildaboat (#153)
Like A.J. says, "we're in a Twilight episode. Enjoy, you can get out during the commercial.
e have very few runways higher than 80,000 feet anyway, and only a couple of them are testing conveyor belt technology. The epitomy of madness or sarcasm.
Adolf Hitler... "What luck for rulers that men do not think." John F. Kennedy... "Those who make peaceful revolution impossible will make violent revolution inevitable."
#168. To: All (#167)
Twilight Zone
Adolf Hitler... "What luck for rulers that men do not think." John F. Kennedy... "Those who make peaceful revolution impossible will make violent revolution inevitable."
#169. To: wakeup, Jhoffa_ (#165)
then where are the extra spins of the landing gear wheels going, mister smartguy? Assuming solid construction and a magical fuel supply that plane is stuck on that conveyor belt forever.
in a plane, nope
And I'm optimistic. See, I think you can be realistic and optimistic at the same time. I'm optimistic we'll achieve -- I know we won't achieve if we send mixed signals. I know we're not going to achieve our objective if we send mixed signals - gwbush
#170. To: Dakmar, tom007, wakeup, markm0722 (#144)
This shall be my last post on this subject (for a least 10 minutes). Of the four aerodynamic forces, two are initially involved in a plane sitting for takeoff: weight and thrust. A high bypass gas turbine does not blast a plane down the runway like a bullet out of a .357 pistol. The pilot throttles and the thrust must overcome the weight of the plane to move the plane forward. As the plane--STARTING out SLOWLY at first--gains speed, lift and drag come into play as the plane approaches take off speed. Then, it is lift which eventually pulls the plane off the ground. The weight of the plane sits on the tires. As thrust is applied, the weight of the plane is pushed along ON THE TIRES if on a STATIONARY surface. If the surface on which the tires (weight of the plane) sits is moving against the rotation of the tires while perfectly matching the speed of the tires, the plane cannot and shall not move. Intial momentum could NEVER be reached to make the plane move. Therefore, it could NEVER reach take off (lift) speed. Again, high bypass gas turbines are NOT rocket engines.
Why should we hear about body bags and deaths. Oh, I mean, it's not relevant. So why should I waste my beautiful mind on something like that? -- Big Mama Bush
#171. To: Dakmar (#169)
I don't know what an extra spin is but, the landing gear are going with the plane... up, up and away.
then where are the extra spins of the landing gear wheels going
Adolf Hitler... "What luck for rulers that men do not think." John F. Kennedy... "Those who make peaceful revolution impossible will make violent revolution inevitable."
#172. To: wbales (#170)
You need to watch the fan on the skateboard movie I posted earlier. I don't know why you are so hung up on the type of engine. It either supplies thrust or it does not. The axle the wheels are mounted on is designed to be as frictionless as possible. How is a frictionless device going to counter the forward thrust?
When prosperity comes, do not use all of it. - Confucious
The nation is prosperous on the whole, but how much prosperity is there in a hole? - Will Rogers
There are 9,000 hedge funds out there. There aren't that many smart people in the world. - Michael Driscoll, a trader at Bear Stearns & Co. in New York
Some days you just want to pull out the Bonehead Stick and beat people senseless. - mirage
#173. To: markm0722 (#172)
It has nothing to do with thrust or friction since the wheels of the airplane would have to remain motionless in order to satisfy the requirement about the conveyor belt counter rotating in opposite direction...
And I'm optimistic. See, I think you can be realistic and optimistic at the same time. I'm optimistic we'll achieve -- I know we won't achieve if we send mixed signals. I know we're not going to achieve our objective if we send mixed signals - gwbush
#174. To: Dakmar (#169)
The conveyer belt is designed to exactly match the speed of the wheels at any given time, moving in the opposite direction of rotation. As the plane reaches 1 mph relative to the ground (not the belt), let's say its tires are spinning at 2 mph (the outside edge). The conveyor belt must therefore be spinning at 2 mph (the upper edge) to match. All conditions are met. As the plane reaches 100 mph relative to the ground (not the belt), let's say its tires are spinning at 200 mph (the outside edge). The conveyor belt must therefore be spinning at 200 mph (the upper edge) to match. All conditions are met. Why the need for infinite rotational speed of the tires? There is no need whatsoever for the speed the tires spin at to be related in any way to the speed the plane is moving. You've got a skateboard sitting on a conveyor belt. The speed that the wheels spin has nothing to do with the speed of the skateboard. Further, the skateboard has a fan sitting on top of it. Nothing is going to counter that force. Picture the inside of the skateboard's ball bearing axles. Picture me accidentally stepping on a skateboard without knowing it is there. You may before it is over, lol. Perhaps you see me at the top of a tall flight of stairs. Now picture how frictionless I picture those wheels once I've reached the bottom. Ouch! Can't say I blame you but I'm not changing my opinion on this.
then where are the extra spins of the landing gear wheels going, mister smartguy? Assuming solid construction and a magical fuel supply that plane is stuck on that conveyor belt forever.
When prosperity comes, do not use all of it. - Confucious
The nation is prosperous on the whole, but how much prosperity is there in a hole? - Will Rogers
There are 9,000 hedge funds out there. There aren't that many smart people in the world. - Michael Driscoll, a trader at Bear Stearns & Co. in New York
Some days you just want to pull out the Bonehead Stick and beat people senseless. - mirage
#175. To: markm0722 (#172)
Bogus. The fan driven skateboard: 1) is moving (gains momentum) before the paper is pulled out from under it; 2) the speed of the paper and the skateboard wheels is not the same and uniform; and, 3) its weight is transferred to the stationary floor under the paper.
Why should we hear about body bags and deaths. Oh, I mean, it's not relevant. So why should I waste my beautiful mind on something like that? -- Big Mama Bush
#176. To: Dakmar (#173)
I think I cover that in my last post. I caught on to why some seem to see a paradox here. The speed of rotation of the wheels must match the speed of the rotation of the conveyor belt, but that does not imply that speed is in any way related to the speed of the plane down the runway. Part of the problem is that rotational speeds really shouldn't be measured in miles per hour, but rather in degrees of rotation per hour. That's what seemingly creates the paradox here. I'd say the brainteaser is a bit poorly worded in that regard.
It has nothing to do with thrust or friction since the wheels of the airplane would have to remain motionless in order to satisfy the requirement about the conveyor belt counter rotating in opposite direction...
When prosperity comes, do not use all of it. - Confucious
The nation is prosperous on the whole, but how much prosperity is there in a hole? - Will Rogers
There are 9,000 hedge funds out there. There aren't that many smart people in the world. - Michael Driscoll, a trader at Bear Stearns & Co. in New York
Some days you just want to pull out the Bonehead Stick and beat people senseless. - mirage
#177. To: markm0722 (#174)
It wouldn't. It couldn't: Thread Rule #1: The conveyer belt is designed to exactly match the speed of the wheels at any given time, moving in the opposite direction of rotation.
As the plane reaches 1 mph relative to the ground
And I'm optimistic. See, I think you can be realistic and optimistic at the same time. I'm optimistic we'll achieve -- I know we won't achieve if we send mixed signals. I know we're not going to achieve our objective if we send mixed signals - gwbush
#178. To: markm0722 (#174)
And keep in mind it says exactly, so let's not hear any whiney explanations about lag time.
And I'm optimistic. See, I think you can be realistic and optimistic at the same time. I'm optimistic we'll achieve -- I know we won't achieve if we send mixed signals. I know we're not going to achieve our objective if we send mixed signals - gwbush
#179. To: wbales (#175)
Bogus? 1) Are you trying to imply that the skateboard would not have moved if the fan had been sitting on it and then turned on? Really? You can't be serious. The skateboard has very frictionless tires. I know. I have accidentally stepped on one in the past, lol. 2) You can clearly see in the video that the speed at which the paper was pulled in no way impacted the speed of the skateboard. By not having it the same and uniform it merely makes the point stronger. The paper conveyor belt had no impact on the speed of the skateboard at numerous different speeds. 3) Of course the weight is transferred to the stationary floor under the paper. That's just like any conveyor belt would be.
Bogus. The fan driven skateboard: 1) is moving (gains momentum) before the paper is pulled out from under it; 2) the speed of the paper and the skateboard wheels is not the same and uniform; and, 3) its weight is transferred to the stationary floor under the paper.
When prosperity comes, do not use all of it. - Confucious
The nation is prosperous on the whole, but how much prosperity is there in a hole? - Will Rogers
There are 9,000 hedge funds out there. There aren't that many smart people in the world. - Michael Driscoll, a trader at Bear Stearns & Co. in New York
Some days you just want to pull out the Bonehead Stick and beat people senseless. - mirage
#180. To: markm0722 (#176)
what else needs to be said tires, wheels, conveyer belt... all irrelevant
The speed of rotation of the wheels must match the speed of the rotation of the conveyor belt, but that does not imply that speed is in any way related to the speed of the plane down the runway.
Adolf Hitler... "What luck for rulers that men do not think." John F. Kennedy... "Those who make peaceful revolution impossible will make violent revolution inevitable."
#181. To: Dakmar (#177)
It wouldn't. It couldn't: Thread Rule #1: The conveyer belt is designed to exactly match the speed of the wheels at any given time, moving in the opposite direction of rotation. There is nothing stopping the plane from moving forward. As the wheels begin to turn, the conveyor belt "exactly" matches the speed of the wheels, whatever that speed ends up being. There is no inconsistency here.
As the plane reaches 1 mph relative to the ground
When prosperity comes, do not use all of it. - Confucious
The nation is prosperous on the whole, but how much prosperity is there in a hole? - Will Rogers
There are 9,000 hedge funds out there. There aren't that many smart people in the world. - Michael Driscoll, a trader at Bear Stearns & Co. in New York
Some days you just want to pull out the Bonehead Stick and beat people senseless. - mirage
#182. To: markm0722 (#181)
The wheels could never move from their their original stop position, any movement they make is counteracted by The Belt. That's the rules, man.
And I'm optimistic. See, I think you can be realistic and optimistic at the same time. I'm optimistic we'll achieve -- I know we won't achieve if we send mixed signals. I know we're not going to achieve our objective if we send mixed signals - gwbush
#183. To: All, SKYDRIFTER (#175)
#184. To: Esso (#183)
What does this have to do with this thread?
God is always good!
"It was an interesting day." - President Bush, recalling 9/11 [White House, 1/5/02]
#185. To: RickyJ (#184)
Airplanes. I'm pinging Skydrifter to the thread, because he may be able to explain to some folks how aircraft function, where myself, I just want to beat half of the people to death on this thread with the back of a shovel because they're so stupid.
What does this have to do with this thread?
#186. To: Dakmar (#182)
That's not what it says. The conveyer belt is designed to exactly match the speed of the wheels at any given time, moving in the opposite direction of rotation. If the wheels are rotating clockwise, then the conveyor belt is rotating counterclockwise. If the outside edge of a wheel is turning at 10 mph, then the outside edge of the conveyor belt is merely turning at 10 mph in the opposite direction. Therefore, there is no slippage between the wheels and the belt at any given time.
The wheels could never move from their their original stop position, any movement they make is counteracted by The Belt. That's the rules, man.
When prosperity comes, do not use all of it. - Confucious
The nation is prosperous on the whole, but how much prosperity is there in a hole? - Will Rogers
There are 9,000 hedge funds out there. There aren't that many smart people in the world. - Michael Driscoll, a trader at Bear Stearns & Co. in New York
Some days you just want to pull out the Bonehead Stick and beat people senseless. - mirage
#187. To: Jhoffa_ (#0)
You are a magician. You are going to do the old pull the tablecloth out from underneath the plates trick. Think of the tablecloth as a conveyor belt. You are a bit worried that some of those plates might choose to stick to the tablecloth and you are really looking to amaze your friends. You decide to mount little ball bearing wheels under each plate to reduce the friction. Good job! You did it! All the plates stayed right in place during the entire pulling of the cloth and you just kept pulling. Infinitely! You thought ahead and got one heck of a long table cloth. The plates just stayed right there on the table. Well done. How did the trick work? Well, you simply couldn't transfer any of the table cloth's (the conveyor belt) energy to the plates. There was a frictionless layer protecting them, in the form of the frictionless ball bearings making up the wheels, much like the nearly frictionless axles of the plane. Oh sure, the wheels on the plates spun big time but the plates never did move. You tried the trick later that night by pulling the table cloth twice as hard. You saw no difference. You have determined that the table cloth being pulled was absolutely irrelevant to where the plates would be. Next up, putting little fans on top of the plates in hopes they actually move. They will. They're sitting on frictionless ball bearing wheels. Once that is complete, it is off to impress your friends with the famous yank the tablecloth out from underneath moving plates trick.
When prosperity comes, do not use all of it. - Confucious
The nation is prosperous on the whole, but how much prosperity is there in a hole? - Will Rogers
There are 9,000 hedge funds out there. There aren't that many smart people in the world. - Michael Driscoll, a trader at Bear Stearns & Co. in New York
Some days you just want to pull out the Bonehead Stick and beat people senseless. - mirage
#188. To: markm0722, Jhoffa_ (#186)
but from a dead stop, the plane would never be allowed to start moving. Can the plane take off? Does "sat on the beginning of" mean, for our purposes, in a state of rest before we started experimenting on it?
Imagine a plane is sat on the beginning of a massive conveyor belt/travelator type arrangement, as wide and as long as a runway, and intends to take off. The conveyer belt is designed to exactly match the speed of the wheels at any given time, moving in the opposite direction of rotation. There is no wind.
And I'm optimistic. See, I think you can be realistic and optimistic at the same time. I'm optimistic we'll achieve -- I know we won't achieve if we send mixed signals. I know we're not going to achieve our objective if we send mixed signals - gwbush
#189. To: markm0722 (#186)
If the outside edge of the conveyer belt is turning at 10 MPH, and the plane is moving at 10 MPH then the rotational speed of the wheels would be 20 MPH. But the conveyer belt is suppose to match the rotational speed of the airplane wheels in this fictional situation. So it must therefore increase its speed until it matches the speed of the airplane wheels, which it can't do if the plane is moving, which it will be if the engines are being revved up. So the airplane wheels and conveyer belt would continue to increase in speed at a very high rate of acceleration until the wheels of plane burn and break off. This is my last post on this fictional issue; there are more important things to talk about, such as the explosives used to take the WTC towers down on 9/11.
If the wheels are rotating clockwise, then the conveyor belt is rotating counterclockwise. If the outside edge of a wheel is turning at 10 mph, then the outside edge of the conveyor belt is merely turning at 10 mph in the opposite direction
God is always good!
"It was an interesting day." - President Bush, recalling 9/11 [White House, 1/5/02]
#190. To: RickyJ (#189)
Here is the condition that must be met. The conveyer belt is designed to exactly match the speed of the wheels at any given time, moving in the opposite direction of rotation The braintwister does not ask the conveyer belt to match the "rotational speed", just the speed. That part of the braintwister is vague and open to many interpretations unfortunately. What part of the tire? Relative to what? The bottom edge of the tire touching the conveyer belt, as seen from the control tower, is moving at 10 MPH backwards up the runway in your example (20 MPH backwards, 10 MPH forwards due to the plane). That's the speed I see the conveyor belt attempting to match. I have been down your path a few times myself, hemming and hawing about what was intended. Further, rotational speed is given in RPM, not miles per hour. In order for the conveyor belt to match rotational speed it would have to rotate once each time the wheel did. I don't think that was intended.
If the outside edge of the conveyer belt is turning at 10 MPH, and the plane is moving at 10 MPH then the rotational speed of the wheels would be 20 MPH. But the conveyer belt is suppose to match the rotational speed of the airplane wheels in this fictional situation.
When prosperity comes, do not use all of it. - Confucious
The nation is prosperous on the whole, but how much prosperity is there in a hole? - Will Rogers
There are 9,000 hedge funds out there. There aren't that many smart people in the world. - Michael Driscoll, a trader at Bear Stearns & Co. in New York
Some days you just want to pull out the Bonehead Stick and beat people senseless. - mirage
#191. To: Dakmar (#188)
Yeah, I'd say so.
Does "sat on the beginning of" mean, for our purposes, in a state of rest before we started experimenting on it?
When prosperity comes, do not use all of it. - Confucious
The nation is prosperous on the whole, but how much prosperity is there in a hole? - Will Rogers
There are 9,000 hedge funds out there. There aren't that many smart people in the world. - Michael Driscoll, a trader at Bear Stearns & Co. in New York
Some days you just want to pull out the Bonehead Stick and beat people senseless. - mirage
#192. To: Dakmar, Jhoffa_ (#188)
In fact, we should know we are in trouble just reading that far. At one point or another some major assumptions are going to be needed, lol. (No offense intended Jhoffa_, I know you got it from Elsewhere.)
Imagine a plane is sat...
When prosperity comes, do not use all of it. - Confucious
The nation is prosperous on the whole, but how much prosperity is there in a hole? - Will Rogers
There are 9,000 hedge funds out there. There aren't that many smart people in the world. - Michael Driscoll, a trader at Bear Stearns & Co. in New York
Some days you just want to pull out the Bonehead Stick and beat people senseless. - mirage
#193. To: Dakmar (#182)
You really have simply answered the question. And the more I think about the wheels and the conveyor belt stipulation, the only way for this jet to take off would be vertically.
The wheels could never move from their their original stop position, any movement they make is counteracted by The Belt. That's the rules, man.
Why should we hear about body bags and deaths. Oh, I mean, it's not relevant. So why should I waste my beautiful mind on something like that? -- Big Mama Bush
#194. To: wbales, Dakmar (#193)
You really have simply answered the question. And the more I think about the wheels and the conveyor belt stipulation, the only way for this jet to take off would be vertically. It is not the correct answer in my opinion. Let's picture 3 scenarios. Scenario #1: A billiard ball is sitting on the runway. There is no conveyor belt. I hit the billiard ball so that it moves 10 mph up the runway. The billiard ball moves up the runway and also spins around its center of mass (its axle so to speak) so that the outside edge is moving at 10 mph. Scenario #2: A billiard ball is sitting on the conveyor belt. I turn the belt on and it is immediately sliding at 10 mph underneath the ball AWAY from the end of the runway. What does the ball do? It does not move. It merely spins so that its outside edge moves at 10 mph. You can verify this for yourself by putting a tennis ball on a piece of typing paper. Pull the typing paper out from under the ball. You will see that for the most part, your efforts only go into spinning the ball and do not go into actually moving the ball towards you. Scenario #3: Combine both forces. Hit the ball and at the EXACT same time (no lag) turn on the conveyor belt. In order to see what happens physics allows us to merely combine the outcomes. The ball WILL move up the runway at 10 mph and spin at 10 mph on its outside edge from hitting it. The BALL will also spin an additional 10 mph on its outside edge from the conveyor belt moving underneath it. Therefore, the ball will move up the runway at 10 mph AND its outside edge will be rotating at 20 mph relative to its center of mass while on the moving conveyor belt. However, as seen from a stationary observer, the bottom part of the ball is moving at the exact same speed as the top of the conveyor belt. There is no slippage. We measure the speed of the plane relative to the stationary observer in the control tower. We have chosen to measure the speed of the conveyor belt relative to the stationary observer in the control tower. Further, we were forced to pick a particular point on the conveyor belt in order for the braintwister to make sense and we chose the point where it touches the wheels. We have chosen to measure the speed of the wheels relative to the stationary observer in the control tower. Further, we were forced to pick a particular point on the wheels in order for the braintwister to make sense and we chose the point where they touch the conveyor belt. The plane, as seen from the control tower, is moving up the runway at 10 mph. The top of the conveyor belt, as seen from the control tower, is moving the opposite direction down the runway at 10 mph. The bottom of the wheels, as seen from the control tower, are also moving down the runway at 10 mph perfectly matching the speed of the conveyor belt. However, the wheels are spinning at a speed high enough to allow the plane to move forward without its wheels slipping. All of these conditions are consistent with what the brainteaser asked of us. I therefore say that upon takeoff the plane's wheels will be spinning exactly twice as fast because of the conveyor belt.
The wheels could never move from their their original stop position, any movement they make is counteracted by The Belt. That's the rules, man.
When prosperity comes, do not use all of it. - Confucious
The nation is prosperous on the whole, but how much prosperity is there in a hole? - Will Rogers
There are 9,000 hedge funds out there. There aren't that many smart people in the world. - Michael Driscoll, a trader at Bear Stearns & Co. in New York
Some days you just want to pull out the Bonehead Stick and beat people senseless. - mirage
#195. To: markm0722 (#194)
If assume that "The conveyer belt is designed to exactly match the speed of the wheels at any given time, moving in the opposite direction of rotation" refers exlusively to the relationship between the wheels and the conveyor belt, you are correct. However, if we assume that we are referring to a fixed point, the plane cannot move relative to that. If two cars are travelling side-by-side at the exact same speed neither is moving in relation to the other, yet they still are moving if observed from a fixed point, so it's basically a matter of which assumptions we are to make.
And I'm optimistic. See, I think you can be realistic and optimistic at the same time. I'm optimistic we'll achieve -- I know we won't achieve if we send mixed signals. I know we're not going to achieve our objective if we send mixed signals - gwbush
#196. To: Dakmar (#195)
Since "speed" in this brainteaser is left relatively (pardon the pun ;)) vague, there are many ways one could read it unfortunately. If one chooses an assumption which forces the tires to rotate to infinite speeds, as other posters have commented, the plane will not take off simply because the landing gear must fall apart. Further, all sorts of other odd effects would happen. The sheer speed of the conveyor belt would certainly create some headwinds. That would be good for lift in the short-term (for the same reason carriers head into the wind before launching fighters), but would the plane potentially stall out as it gained altitude and therefore removed itself from those headwinds? In fact, one might even argue that the landing gear using my assumptions might fall apart. Are the plane's tires able to rotate at double their usual rate without incident? The rotational energy goes up as the square of the rotational speed. The tires on my car may handle 100 mph, but do I really want to try 200 mph? Other people might choose assumptions which form paradoxes. That does not necessarily mean they are wrong. It is a brainteaser after all. It wouldn't be the first time paradoxes were intentionally inserted to make people think. It is too bad the brainteaser isn't more clear. It seems to me that more than an average amount of assumptions must be made.
If assume that "The conveyer belt is designed to exactly match the speed of the wheels at any given time, moving in the opposite direction of rotation" refers exlusively to the relationship between the wheels and the conveyor belt, you are correct. However, if we assume that we are referring to a fixed point, the plane cannot move relative to that. If two cars are travelling side-by-side at the exact same speed neither is moving in relation to the other, yet they still are moving if observed from a fixed point, so it's basically a matter of which assumptions we are to make.
When prosperity comes, do not use all of it. - Confucious
The nation is prosperous on the whole, but how much prosperity is there in a hole? - Will Rogers
There are 9,000 hedge funds out there. There aren't that many smart people in the world. - Michael Driscoll, a trader at Bear Stearns & Co. in New York
Some days you just want to pull out the Bonehead Stick and beat people senseless. - mirage
#197. To: markm0722 (#196)
Live and learn, that's what I say. Not all the time, but now, for instance.
It is too bad the brainteaser isn't more clear. It seems to me that more than an average amount of assumptions must be made.
And I'm optimistic. See, I think you can be realistic and optimistic at the same time. I'm optimistic we'll achieve -- I know we won't achieve if we send mixed signals. I know we're not going to achieve our objective if we send mixed signals - gwbush
#198. To: markm0722 (#196)
Am I saying "now" in real time, or on this thread?
And I'm optimistic. See, I think you can be realistic and optimistic at the same time. I'm optimistic we'll achieve -- I know we won't achieve if we send mixed signals. I know we're not going to achieve our objective if we send mixed signals - gwbush
#199. To: Dakmar (#197)
Here's something I was worked on last night adapted from a paradox I remember seeing a long time ago. Presidential Paradoxes A taxpayer is standing before 2 doors numbered #1 and #2. President Bush says to him, "You must open the doors sequentially. Behind one of the doors is $8 trillion in national debt. If you open the door and are surprised to see it in there you must pay it in full. If you are not surprised, you won't have to pay. I can tell you this though, you will most certainly be surprised when you see it." The taxpayer is no dummy. He thinks to himself, "If I open door #1 and do not see the debt, the debt must be behind door #2. When I then open door #2 I can't possibly be surprised to see the debt there as it would be the only door left to open. Yet, the president assured me I would be surprised. Therefore, the debt cannot be behind door #2. The debt must be behind door #1." The taxpayer steps up to door #1. Just as he starts to open it he recalls the president's words, "I can tell you this though, you will most certainly be surprised." The taxpayer suddenly realizes that the debt cannot be where he thinks it is. It cannot be behind door #1 and proceeds to open it. There's the $8 trillion debt. It surprises him to see it there! President Bush laughs. The taxpayer is amazed at the President's ability to foresee this tragic turn of events. President Bush says to him, "Here are 2 more doors. Behind one of them lies the weapons of mass destruction we found in Iraq. If you open the doors and are not surprised by what you see I will forgive you of your $8 trillion debt. I can tell you this though, you will most certainly be surprised." The taxpayer is no dummy. He sees that this is the exact same situation as before. He steps up to door #1. He fully expects to see the weapons of mass destruction behind the door. He opens it. There are no weapons of mass destruction. It surprises him. He runs over to door #2. He knows they must be in there. It is the only place left they could possibly be. He opens the door. They aren't in there either. He's surprised yet again. He exclaims, "There are no weapons of mass destruction behind either door! How can this be?" President Bush says, "I lied again." He then falls to the floor laughing. Moral of the story: Nothing beats a good laugh at the taxpayer's expense. ;)
When prosperity comes, do not use all of it. - Confucious
The nation is prosperous on the whole, but how much prosperity is there in a hole? - Will Rogers
There are 9,000 hedge funds out there. There aren't that many smart people in the world. - Michael Driscoll, a trader at Bear Stearns & Co. in New York
Some days you just want to pull out the Bonehead Stick and beat people senseless. - mirage
#200. To: Dakmar (#198)
You are asking the guy who just posted, "Here's something I was worked on last night..." Doh! Need more sleep! Must stop thinking about how messed up our future is! ;)
Am I saying "now" in real time, or on this thread?
When prosperity comes, do not use all of it. - Confucious
The nation is prosperous on the whole, but how much prosperity is there in a hole? - Will Rogers
There are 9,000 hedge funds out there. There aren't that many smart people in the world. - Michael Driscoll, a trader at Bear Stearns & Co. in New York
Some days you just want to pull out the Bonehead Stick and beat people senseless. - mirage
#201. To: markm0722 (#200)
At least persecutors are persecuted here. Good enough for me.
And I'm optimistic. See, I think you can be realistic and optimistic at the same time. I'm optimistic we'll achieve -- I know we won't achieve if we send mixed signals. I know we're not going to achieve our objective if we send mixed signals - gwbush
#202. To: Jhoffa_ (#0)
Assuming the conveyor is actually matching the speed of the wheels - no, there would be no airflow for the required lift.
Top • Page Up • Full Thread • Page Down • Bottom/Latest