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Somthing to make you think


SS Silv

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See, herein lies my problem with this question: It's very poorly worded. It poses what will happen but doesn't allow for anything to happen. Here's my response to this:

 

If the question is asking about what happens during the instant that the plane is making the same amount of thrust as the runway is moving the other direction (poorly worded I know but that's how it has to be w/o using units): Liftoff? No. No lift, at all. The plane will be moving forwards, sure. Thanks to the simple idea of thrust. The plane will accelerate down the runway (provided the wheels don't explode, yada yada yada). The runway can go into light speed in the other direction w/o affecting the plane's thrust.

 

If the question is asking about what will happen if the experiment runs until a proposed solution is attained: Duh. Liftoff. If the runway is 2 miles long (or w/e, it only has to be a little bit longer than normal to make up for the friction it's giving the wheels as it goes in the other direction), then eventually the plane will lift off. It will continue to accelerate down the runway and eventually have enough lift to go airborne. It might even happen faster seeing as how the runway is also generating friction with the air and pulling it along in its direction of travel (i.e. towards the airplane), however that would be false lift as the plane wouldn't then have the velocity to attain the lift that that kind of pseudo-ground-effect generates.

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Now that I've had a year and a half to think about this..LOL... I still think the plane will build forward momentum and take off.

 

yes of course but then where is the riddle? obviously if/ when it overcomes the oppisite speed of the treadmill, then yes, but the way i read it is if the plane stays in one spot matching the speed of the treadmill. but then the wheels would be going twice the speed and either fall off or blow up, or both.

 

CA_jetblue_landing.JPG

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If the planes forward power was generated through the wheels I think the plane would stay staitionary. Since the thrust is generated from the prop/jet, the fact that it's on the conveyor is irrelevant. The air resistance caused from the wind speed is what'll push the plane forward.

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this is a trapped question. I investigated this last night on my genious forum that I like to read,notice i said read and not comment..lol, and they said this is an impossible question to answer because of the parameters are not given. It says the conveyer moves as fast as the plane but doesnt specify wehter that means the fuselodge (sp?) or the heels and it does matter apparantly.

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Yes it would fly/take off. as stated before....it is the propultion of the engine pushing AIR that makes the air craft move forward. and if you accellerate you are going to create lift. question for those who say no.....how does the plane still accelerate in flight if the landing gear is up? the wheels when on the ground are only going to create a slight amount of drag when free wheeling. no if the brakes were engaged it would be a different story as well....then it would be a battle of tire rubber vs treadmill. it is simple because the wheel are free rolling.

 

on a side note this is how lift is created:

 

air moving over the top part of the has to move faster then the lower part of the wing. this creates lower pressure on the top of the wing thus creating lift. the reason that the air HAS to move over the top part of the wing is due to bernoulli's theorm.

 

lift1.jpg

 

sorry i hope i don't step on anyone's toes.

hope this helps.

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hope this helps.

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no it doesn't, i still do not believe it, until i see it. all these words that were copied and pasted mean nothing without physical evidence. so until i see an airplane take off like this i won't believe it.

 

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  • 3 months later...
A plane is standing on a runway that can move (some sort of band conveyer). The plane moves in one direction, while the conveyer moves in the opposite direction. This conveyer has a control system that tracks the plane speed and tunes the speed of the conveyer to be exactly the same (but in opposite direction).

 

The question is:

 

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

OMG, I can't beleive an explanation of this is even necessary!

 

The thrust of the engine will increase air speed (speed relative to the surrounding air). It doesn't matter if the conveyor was running at the freaking speed of light in the opposite direction (as long as the wheel bearings held up LOL). It is the air flow over the wings that creates lift. The curve of the wing is shaped in such a way as to make the distance traveled over the wing longer on the top surface. This creates a low pressure on the top surface of the wing and creates lift. This is based on Bernoullie's Principle which states that as air (or fluid) speed increases, pressure decreases.

 

There's your PHYS 101 lesson for the day.

 

Mike

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It will not fly...bottom line...the wing isnt cutting wind therefore gaining lift....The wheels would be moving at the appropriate speed to create take off but the plane itself wouldn't be....very complicated question very simple answer

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