RE: Can It Take Off??  
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RE: Can It Take Off?? - 12/15/2005 5:48:04 AM   
boss2nine


 

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Bug in the jar question? Is that kinda like the chicken or the egg thing.

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RE: Can It Take Off?? - 12/15/2005 5:50:01 AM   
air mail rcu


 

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Imagine an airplane is on the beginning of a massive conveyor belt, 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.

Match the speed. To me that means the wheels can not go faster then the threadmill.

What does that mean to you?

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RE: Can It Take Off?? - 12/15/2005 1:17:01 PM   
dick Hanson



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It means . the riddle is an unworkable question, (nonsense).
wheel rotation/belt rotation is not controlling the force moving the plane forward.
logic :
plane moves forward- wheels in friction contact require the belt allows this rotation and wheels spin-OR- plane moves forward - belt moves in same direction- NO wheel rotation
In either case - the plane just -- takes off

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RE: Can It Take Off?? - 12/15/2005 4:39:15 PM   
air mail rcu


 

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With your logic, the wheels are going faster then the belt.

The belt won't allow that. According to the question the plane does not fly.

I think it's a very workable question. Someone with the resouces just needs to work the problem.



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RE: Can It Take Off?? - 12/15/2005 6:29:55 PM   
britbrat


 

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The wheels have nothing to do with flying.

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RE: Can It Take Off?? - 12/16/2005 1:04:48 AM   
air mail rcu


 

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While there connected to the ground they do.

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RE: Can It Take Off?? - 12/16/2005 1:09:06 AM   
CHassan



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All they do is spin

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RE: Can It Take Off?? - 12/16/2005 2:05:59 AM   
air mail rcu


 

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Thats right

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RE: Can It Take Off?? - 12/16/2005 2:29:57 AM   
Wes The Mess


 

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the answer is it depends on how much friction the wheels produce--think of it as the plane has no engines and you are standing behind it pushing it forward--the friction from the wheels turning will cause the plane to push back against your hand and you are only strong enough to push it to a certain speed which the friction will push back against--since the wheels dont produce that much friction but they do produce SOME friction, the wheels will spin a lot faster than the plane can fly so that the friction can match the thrust--the reason the plane wont take off is because every time the wheels speed up, the conveyer belt speeds up also and the plane cant move forward because the wheels must spin faster than the conveyer belt for the plane to move forward but since the conveyer belt always matches the wheel speed (reminds me of spooky action at a distance which would constitute time travel--but this assumes that there is no time travel or spooky action at a distance so the conveyer belt will always match the wheel speed in this problem), the wheels cant move forward so the plane will never achieve forward airspeed--assuming the wheels can withstand any speed and the conveyer belt produces no air movement, the plane will not move and therefore will not take off--i know its weird to think that the wheels can spin much faster than the plane can fly but thats what will happen...

the plane will not fly, i rest my case...

EDIT: i also forgot to mention this assumes the aircraft NEEDS forward airspeed to take off and cannot take off unless it has some airspeed (i.e. it cant take off from the props airflow)

< Message edited by Wes The Mess -- 12/16/2005 2:44:33 AM >

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RE: Can It Take Off?? - 12/16/2005 5:38:33 AM   
dick Hanson



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Woof! (no)

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RE: Can It Take Off?? - 12/16/2005 12:22:16 PM   
15thAF


 

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quote:

ORIGINAL: Wes The Mess

...the reason the plane wont take off is because every time the wheels speed up, the conveyer belt speeds up also and the plane cant move forward because the wheels must spin faster than the conveyer belt for the plane to move forward but since the conveyer belt always matches the wheel speed ...



If the plane never moves forward, please explain how the wheels ever speed up.

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RE: Can It Take Off?? - 12/16/2005 12:49:11 PM   
CHassan



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quote:

ORIGINAL: 15thAF


quote:

ORIGINAL: Wes The Mess

...the reason the plane wont take off is because every time the wheels speed up, the conveyer belt speeds up also and the plane cant move forward because the wheels must spin faster than the conveyer belt for the plane to move forward but since the conveyer belt always matches the wheel speed ...



If the plane never moves forward, please explain how the wheels ever speed up.



If you spin the wheels to stop the plane is the engine ever going to stop trying to accelerate? No. That means the wheels will never stop accelorating until they create a cosmic shift that brings Jupiter smashing into the surface of the earth. It will hit in china and the plane will be thrown into the air. On its way down it will pick up airspeed and fly as if nothing was wrong. (until jupiter smashes all the way through the planet and thus smashes the plane.)

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RE: Can It Take Off?? - 12/17/2005 7:02:23 AM   
Wes The Mess


 

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15thAF--thats what i was saying about spooky action at a distance...the conveyer belt and the wheels spin simultaneously to compensate for the engine thrust--in order for the plane to move forward, the wheels must be moving faster than the conveyer belt, right?...but since the wheels and the conveyer belt spin at the same speed, the wheels can not move faster which means the plane can not move forward--if you want, i can explain it like i would to a 3 year old...if you run on a treadmill and you run off the front of the treadmill, the reason is because you were running faster than it, right? but if you start to run faster and push the speed up button at the same time, you will stay on the treadmill because you are running faster and the treadmill is moving faster

simply put, without time travel, theoretically this experiment would not even be possible to conduct--so you are right and i did think of this as i was typing which is why i put all that junk in parenthesis and said i assumed there was no spooky action at a distance or time travel involved so the experiment was possible--if you had quoted a little more you might have been able to figure this out

CHassan--there will be a point where the wheels stop accelerating, when the engine reaches maximum rpms and cant push any harder so the wheels dont have to spin faster to compensate for more thrust because there is no more thrust--oh, and if the wheels never actually did stop accelerating, the cosmic shift would only cause jupiter to smash into the surface of the earth between the months of july and december because of the gravity of the sun and location of the planets...between january and june, it can be either neptune or saturn that get pulled onto a collision course with earth and if it is february 29th on a leap year, the universe will most likely implode because the cosmic shift would have nothing to pull and therefore would pull space--so for any of you who want to attempt this stunt, please do not try it on february 29th...

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RE: Can It Take Off?? - 12/17/2005 2:08:40 PM   
CHassan



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quote:

ORIGINAL: Wes The Mess

15thAF--thats what i was saying about spooky action at a distance...the conveyer belt and the wheels spin simultaneously to compensate for the engine thrust--in order for the plane to move forward, the wheels must be moving faster than the conveyer belt, right?...but since the wheels and the conveyer belt spin at the same speed, the wheels can not move faster which means the plane can not move forward--if you want, i can explain it like i would to a 3 year old...if you run on a treadmill and you run off the front of the treadmill, the reason is because you were running faster than it, right? but if you start to run faster and push the speed up button at the same time, you will stay on the treadmill because you are running faster and the treadmill is moving faster

simply put, without time travel, theoretically this experiment would not even be possible to conduct--so you are right and i did think of this as i was typing which is why i put all that junk in parenthesis and said i assumed there was no spooky action at a distance or time travel involved so the experiment was possible--if you had quoted a little more you might have been able to figure this out

CHassan--there will be a point where the wheels stop accelerating, when the engine reaches maximum rpms and cant push any harder so the wheels dont have to spin faster to compensate for more thrust because there is no more thrust--oh, and if the wheels never actually did stop accelerating, the cosmic shift would only cause jupiter to smash into the surface of the earth between the months of july and december because of the gravity of the sun and location of the planets...between january and june, it can be either neptune or saturn that get pulled onto a collision course with earth and if it is february 29th on a leap year, the universe will most likely implode because the cosmic shift would have nothing to pull and therefore would pull space--so for any of you who want to attempt this stunt, please do not try it on february 29th...



If the engine is tied to a test stand, lets say it produces 10lbs of thrust.
Does it ever stop producing 10lbs of thrust?
So if 10 lbs of thrust will move a plane at 10mph IAS and the plane never reaches 10mph IAS does it ever stop trying?? Nope so you will never reach a point where the wheels stop accelerating. If you do the engine will still be trying to move the plane through the air at 10mph IAS.

Now if the wheels do stop spinning they will ba at a VERY high rate of rotation. Every little bump, vibration, of nuance on the conveyor or treads will cause a loss of friction between the tire and the surface of the conveyor. At some point I'd be willing to bet that the tire, due to this loss of friction, will begin to skid. Once it starts skidding the plane will have the ablility to advance down the runway and reach take off speed.







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RE: Can It Take Off?? - 12/17/2005 3:22:11 PM   
air mail rcu


 

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Not according to the question. In order for the tires to skid the belt would not match the exact speed of the tires. The tires can not skid.

What makes you think there are bumps, vibrations or nuances in or on the belt or tires? You are adding things to the questions. There is no mention of these. If you just answer the question as stated and stop adding and subtracting things you will see the plane can not fly.

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