mugged an east indian man and stole his name.

I should read this now and again.

Naw. But ricking is in no way dishonest

You bastard

All mass media is a joke. CNN and MSNBC are just as big of liars.

>"he wheels don't start sliding"

I admit on that I was wrong. This doesn't change the fact that the 747 using more then about 1% of it's thrust won't be held stationary by a conveyor though. The conveyor no-Ahh Mid sentance screw it. I just don't give a damn about you wanting to restrict the problem.

The question is "Can the plane take off?" Your thinking about it in the wrong way. You're already assuming the conveyor will hold the plane stationary. The question isn't about can a stationary plane take off because the conveyor is incapable of producing such conditions.

Lets start with a car:
A car on a conveyor that spins in the opposite direction of the car's tires at the same velocity will keep a car still. No matter how much the car rev's it's engine it will never move relative to an observer. You agree with this right? A plane is different from a car though.

Here;s how:
Imaging a car on a super smooth surface that had ZERO friction. If a car floors it's engine will it move forward? No. You agree with this right? The car depends exclusively on the friction of it's tires to move forward.

Now say we put a plane on this zero friction surface. It throttles it's engines up to full power. Will it move forward even though it's tires have zero traction? Yes. The plane will move forward. The plane moves independent of it's tires friction. It's this very same principle that prevents a conveyor from keeping a plane still. The conveyor isn't countering the engines thrust because the plane is not moving by transferring energy through it's tires.

Thus the question isn't "can a stationary plane take off" because the circumstances we're given won't hold back a plane.

The stem cell ban being lifted brings me one step closer to eating dead babies.

>well anyways, she had the best taco I'd ever eaten in my life

I think you're lying. No one likes eating tacos. You suffer through it so you can get some back.

Isn't even worthy of sexing Flint.

>The wheels and conveyer belt are of equal and opposite velocitites, but after a point due to a lack of the wheels capabilites of turning FOR SOME REASON, the wheels start to slide over the conveyer belt accelerating the aircraft from 0m/s to some take off velocity.

No. The wheels don't start sliding. The conveyor can never put more then 2klb of force apposing the plane. The wheels still turn at the same speed as the conveyor which is now the speed the conveyor was going when the plane was being held back by the conveyor [PLUS] the planes speed relative to the observer. The plane accelerates and takes off with it's wheels now spinning [Much faster then normal].

The wheels don't skid when the plane starts to move relative to the observer. The wheels/conveyor just move faster. The conveyor can't push against the plane more then 2klb which isn't going to stop a 747's 200klb of potential thrust.

@Avo

Maybe you don't get that this problem is NOT about can a plane take off when standing still. It's really asking can a conveyor hold back a plane. A conveyor can hold back a car, but it cannot hold back a plane. That's what I've been writing. That's what you don't get. You keep talking about the conveyor continually matching the wheel speed and thinking that has any effect. The conveyor just can provide enough friction to hold back a plane. End of story.

Avo Don't talk to me until you shave.

<Pixie> A10..this question is different to the questions you're looking at elsewhere. In this question, the conveyer belt matches the speed of the WHEELS not the speed of the 747.

The conveyor can move as fast as it wants- matching the speed of the wheels or doubling the speed of the wheels. The max force against the plane from the conveyor is still about 2000lb and can only hold the plane back as long as the plane never exerts a thrust more then 2000lb or about 1% of it's max thrust.

<Avo> correct. BUT when the 747 becomes no longer stationary, the wheels are moving faster then the conveyor belt; right?

Not quite.The wheels are now going faster then the plane. The conveyor matches the speed of the wheels. The wheels and the conveyor are now going the speed they were when the plane was stationary on the conveyor plus the speed of the plane relative to the observer.

<Avo continued> do you understand that? now the original post in this thread asks, if the plane can take off if the conveyor belt matches the speed of the wheels.

The conveyor matches the speed of the wheels even when the plane stops being stationary. The wheels and conveyor just move at the speed of the plane plus the speed they were going previously. It's irrelevant though because the conveyor can never push against the plane more then about 2klb.

SO a 747 on a conveyor that PERFECTLY matches the speed of the WHEELS will still move forward relative to the ground and take off and the wheels and the conveyor will still be matched in speed.

<Avo>so he's asking if the plane can take off before the engine's thrust makes the wheels travel faster then the conveyor

Lol. You're thinking that once the plane moves forward the conveyor and the wheels aren't matched in speed. The wheels turn faster as the plane accelerates. The wheels never travel faster then the conveyor because as the wheels increase in speed the conveyor increases as well.

The conveyor increases to match the speed of the wheels but they still never exert a force greater then about 2klb against the plane. They don't stop the plane from moving but the wheel and the conveyor are still moving at the same speed.

[Humidity]>imagine your in a car.. you put your foot on the brake and press the accelerator.. your wheels dont movee forward, because the force pushing the car forward is equal to the brakes...

the same applies to the plane theory.. therefore the whells are stationary so the plane does not move..

I say this nicely but you are completely wrong. Rather then repeating myself again just think about this. You are saying that a plane relies on it's friction with the ground to move forward. If a plane needed it's wheels to push against the ground to move in a forward direction then at 35000 ft where there is no ground the engines would not be moving the plane.

Anyways back to what avo was saying. . .

[Avo]>ok, now at the very beginning. the conveyor is turned on, lets say it moves 20mph; the pilot turns on the engine, very low, so that the wheels are going 20mph. when the wheels and the conveyor are both going 20mph, the airplane isnt moving. its stationary. because the rate the wheels are turning is canceled by the equal rate of the conveyor. now no matter how much you speed this up, even if the wheels are turning at the speed of light, the plane will be stationary if the conveyor is moving at the same speed as the wheels.

Ok I concede that the above is right up to a certain thrust from the engine.

First all the coefficients of friction I'm using come from this page: http://www.roymech.co.uk/Useful_Tables/Tribology/co_of_frict.htm

And some info about a 747-100 from here: http://www.airliners.net/aircraft-data/stats.main?id=97
Max takeoff weight: 750,000lb
Max thrust(all 4 engines combined): 187,800lb
Tire radius: 4ft
Number of tires: 16
Hard rubber on cement coefficient: 0.01 (assuming for simplicity the conveyor has the same coefficient as the runway normally would)

Rolling friction of a 747:
F  in Newtons = number of tires * Coefficient of Hard rubber on Cement * weight in kg per tire * 9.81
16 * 0.01 * (85,184.6471/16) * 9.81 = 8356 n or 1878.5lb

This number is the maximum amount of force the conveyor at any speed - matching the wheels speed or not- could exert against the plane.

This means the 747 would be held stationary by the conveyor belt like you said it would until it's engines exerted more then about 1 ton of thrust. Remember the 747 can exert 187,000lb of thrust.