Okay, What The Hell...

[Gavyn.]

We could argue about this all night, but the point is the plane may or may not take off depending on the wording of the question, so who actually cares weather it takes off. unless one of you plans to drive a plane up a giant treadmill?

[Tomm]

Er... JT I thought you knew what you were on about but this is bollocks:

The tredmill matches the speed of the plane. So when the plane starts to move, the tredmill speeds up, it will have to go very fast to try and keep the plane stationary, to the point where it would destory a wheel, or the friction would be holding the plane back.

The treadmill 'matches' the speed of the plane means that the treadmill will be going at the same speed as the plane. I.e. Plane going forward @ 200mph, treadmill running @200 mph, wheels spinning @ 400mph. The question says nothing about the treadmill cancelling out the speed of the plane to keep it stationary or anything like that

[adamtrials]

No conveyor could physically stop a plane from moving forward no matter how fast the conveyor is?

The friction arguement is rubbish, the plane I fly can take off at about 50mph at a push, and can be landed relativley safely at over 100mph, i've seen it done. And this is on a windless day, so the indicated air speeds are roughly the same as the ground speeds. The wheels don't lock up or anything. Plane wheels are very tough things.

No conveyor could actually match the speed of the wheels of a vehicle that is moving forward.

Like Tomm said, you can always push a toy car forward on a conveyor and the wheel speeds will not be equal to the conveyor.

The question is flawed.

[Dan6061]

Surely it'd just be the wheels going faster?

So the jets etc on the plane would still push it along at the right speed?

[adamtrials]

Surely it'd just be the wheels going faster?

So the jets etc on the plane would still push it along at the right speed?

Yeah.

[Token]

Ofcourse it doesn't take off!

What a stupid analogy! You silly lesbians.

To put it simply..... if the treadmill/conveyer belt is matching the speed at which the wheels are turning, then the plane doesnt actually move anywhere. (think of a rolling road/dyno) So if the plane isn't physically moving forwards then there is no air passing over the wings. If there is no air passing over the wings then the plane can't take off.

It'd be a different scenario if the plane needed 100 KPH to take off and the plane was not moving but there were gusts of wind at 100 KPH blowing towards the plane, there's a reason why planes fly into the wind when they take off. It reduces their take off speed, 30 KPH headwind means they only need to get to 70 KPH.

I could just be going off on a tangent here and I haven't answered the question, because I didn't read the question.

[Pashley26]

You lot are f**king stupid.....

Jarrod

[Muel]

Ofcourse it doesn't take off!

What a stupid analogy! You silly lesbians.

To put it simply..... if the treadmill/conveyer belt is matching the speed at which the wheels are turning, then the plane doesnt actually move anywhere. (think of a rolling road/dyno) So if the plane isn't physically moving forwards then there is no air passing over the wings. If there is no air passing over the wings then the plane can't take off.

It'd be a different scenario if the plane needed 100 KPH to take off and the plane was not moving but there were gusts of wind at 100 KPH blowing towards the plane, there's a reason why planes fly into the wind when they take off. It reduces their take off speed, 30 KPH headwind means they only need to get to 70 KPH.

I could just be going off on a tangent here and I haven't answered the question, because I didn't read the question.

The jets are pushing the plane along, not the wheels.

The jet's are not connected to the conveyer belt, so the conyeyer belt has no effect over the movement of the plane.

The plane takes off. The small toy car doesn't take off.

[*Tom*]

The jets are pushing the plane along, not the wheels.

It dosen't matter whats pushing the plane, it the plane is doing X speed and the tredmill is doing the same speed the plane won't move.

[JT!]

Er... JT I thought you knew what you were on about but this is bollocks:

The treadmill 'matches' the speed of the plane means that the treadmill will be going at the same speed as the plane. I.e. Plane going forward @ 200mph, treadmill running @200 mph, wheels spinning @ 400mph. The question says nothing about the treadmill cancelling out the speed of the plane to keep it stationary or anything like that

If the tredmill is running at 200mph and the plane is going forward at 200mph and the wheels are running at 400mph. The plane would be stationary, and that would mean the tredmill shouldn't be moving becuase the relative speed of the plane, from the floor the tredmill is on, is zero.

[ZeroMatt]

NOOOO you muppet it WILL take off.

The jet works by producing thrust with engines that dont have anything to do with the ground. The wheels have absolutley nothing to do with the driving force, simply the jet engines move air to make it move. Nothing to do with the ground.

If the wheels had anything to do with the plane flying why would it even be able to fly as when it took off it wouldn't have anything driving it forward so would just take off then air resistance would mean it would slow down and not have enough lift to stay in the air.

[JT!]

NOOOO you muppet it WILL take off.

The jet works by producing thrust with engines that dont have anything to do with the ground. The wheels have absolutley nothing to do with the driving force, simply the jet engines move air to make it move. Nothing to do with the ground.

If the wheels had anything to do with the plane flying why would it even be able to fly as when it took off it wouldn't have anything driving it forward so would just take off then air resistance would mean it would slow down and not have enough lift to stay in the air.

If that was directed at me i know that.

I think we've gone past the point of deciding wether the plane will take off or not, and it's more down to disscussing the question, and how it's been interpreted.

EDIT: actually, i see it was probably directed at *tom*, what he said makes sence, even when the engines force the plane forward, the question says it tracks the speeds plane and the tredmill speeds up to compensate. So the tredmill will speed up to stupid speeds to use the friction in the wheels to keep it still. However, wether a tredmill can reach those speeds is up for debate. However, the question implys that it can.

Edited December 31, 2007 by JT!

[ZeroMatt]

If that was directed at me i know that.

I think we've gone past the point of deciding wether the plane will take off or not, and it's more down to disscussing the question, and how it's been interpreted.

Was for Tom blokey on page 3

[Simpson]

Anyone who says the plane wont move is STUPID

the acceleration of the plane is not throught the tyres

it acts directly on the body, so it must move

if the tollerances of the tyres are great enough the plane will take off

[*Tom*]

Yes but the plane needs to be moving forwards to take off, so if the treadmill is going the same speed as the plane that cancels out the planes speed, so i won't be moving forwards, so will not take off!!

[Simpson]

Yes but the plane needs to be moving forwards to take off, so if the treadmill is going the same speed as the plane that cancels out the planes speed, so i won't be moving forwards, so will not take off!!

The plane needs to be going forwards.... the wheels do not

[JT!]

Was for Tom blokey on page 3

Edited.

Anyone who says the plane wont move is STUPID

the acceleration of the plane is not throught the tyres

it acts directly on the body, so it must move

if the tollerances of the tyres are great enough the plane will take off

See what i just wrote...

If that was directed at me i know that.

I think we've gone past the point of deciding wether the plane will take off or not, and it's more down to disscussing the question, and how it's been interpreted.

EDIT: actually, i see it was probably directed at *tom*, what he said makes sence, even when the engines force the plane forward, the question says it tracks the speeds plane and the tredmill speeds up to compensate. So the tredmill will speed up to stupid speeds to use the friction in the wheels to keep it still. However, wether a tredmill can reach those speeds is up for debate. However, the question implys that it can.

Yes but the plane needs to be moving forwards to take off, so if the treadmill is going the same speed as the plane that cancels out the planes speed, so i won't be moving forwards, so will not take off!!

I agree. But the temil would have to go so fast to create friction in the wheels to start dragging it backwards.

[ManxTrialSpaz]

Yes but the plane needs to be moving forwards to take off, so if the treadmill is going the same speed as the plane that cancels out the planes speed, so i won't be moving forwards, so will not take off!!

But that's only if the friction of the wheels is so large that it will cancel out thousands of pounds of thrust. Which it wouldn't be, otherwise a plane would crash everytime it landed, as the wheels would come to a dead halt.

[JT!]

The plane needs to be going forwards.... the wheels do not

But the plane can't move forward because the original question says that it can't.

But that's only if the friction of the wheels is so large that it will cancel out thousands of pounds of thrust. Which it wouldn't be, otherwise a plane would crash everytime it landed, as the wheels would come to a dead halt.

It would if the belt was going backwards at 4000mph. Or the wheel would blow at much less speeds and then it'd just be on it rim, and then it wouldn't be able to take off.

Edited December 31, 2007 by JT!

[Simpson]

See what i just wrote...

I've read the whole thread.... you need to understand the 2 SEPERATE events

1. The engine pushing the body forwards, (not the wheels) but the mass of the plane

2. The wheels that are not being driven and so are effectivly in "free motion" (ish) they can spin which ever way they goddam like e.g

wheels --> 200mph

treadmill <-- 200mph

I can understand why you dont think the plane will still move, but it will, the point of acceleration is not through the tyres like a conventional car but instead through the mass (jet engines on the plane) so it will continue to accelerate

wheels -->50

treadmill <-- 50

wheels --> 100

treadmill <-- 100

wheels --> 150

treadmill <-- 150

Until it gets fast enough to take off.... if i had a treadmill in my garage id demonstrate

[*Tom*]

It would if the belt was going backwards at 4000mph. Or the wheel would blow at much less speeds and then it'd just be on it rim, and then it wouldn't be able to take off.

Hes right

If the treadmill was doing 100mph, the plane would have to do 100mph + the ammount of speed it would usually need to take off.

2. The wheels that are not being driven and so are effectivly in "free motion" (ish) they can spin which ever way they goddam like e.g

wheels --> 200mph

treadmill <-- 200mph

I can understand why you dont think the plane will still move, but it will, the point of acceleration is not through the tyres like a conventional car but instead through the mass (jet engines on the plane) so it will continue to accelerate

wheels -->50

treadmill <-- 50

wheels --> 100

treadmill <-- 100

wheels --> 150

treadmill <-- 150

The wheels might not be driving the plane but aslong as it is still moving at the same speed as the treadmill it won't move

Edited December 31, 2007 by *Tom*

[Simpson]

But the plane can't move forward because the original question says that it can't.

able to take off.

An aircraft is standing on a runway that can move (a conveyor belt). The aircraft moves in one direction, while the conveyor moves in the opposite direction. This conveyor has a control system that tracks the aircraft's speed and tunes the speed of the conveyor to be exactly the same, but in the opposite direction. There is no wind. The pilot begins to add thrust to the engines...

The convayor belt moves in the opposite direction, not the mass of the plane.... at no point does the question say the plane can or cant move

Hes right

If the treadmill was doing 100mph, the plane would have to do 100mph + the ammount of speed it would usually need to take off.

The wheels dont help the plane move forward in anyway, they just support the weight of the plane till it takes off

so it will need exactly the same ammount of power as usualy ( + whatever the - of friction is but its all negligble really)

[ZeroMatt]

Hes right

If the treadmill was doing 100mph, the plane would have to do 100mph + the ammount of speed it would usually need to take off.

Incorrect. It's the plane determining the speed of the treadmill, also the friction isn't exactly like driving through a swamp.

[JT!]

I've read the whole thread.... you need to understand the 2 SEPERATE events

1. The engine pushing the body forwards, (not the wheels) but the mass of the plane

2. The wheels that are not being driven and so are effectivly in "free motion" (ish) they can spin which ever way they goddam like e.g

wheels --> 200mph

treadmill <-- 200mph

I can understand why you dont think the plane will still move, but it will, the point of acceleration is not through the tyres like a conventional car but instead through the mass (jet engines on the plane) so it will continue to accelerate

wheels -->50

treadmill <-- 50

wheels --> 100

treadmill <-- 100

wheels --> 150

treadmill <-- 150

Until it gets fast enough to take off.... if i had a treadmill in my garage id demonstrate

I undersand all that, what i'm saying is once the plane starts to move forward through the air, the belt will notice the movement and speed up to try and stop the plane moving, becuase the wheels are just to keep the plane off it's belly, this wont do anything.

...untill it reaches high speeds, where the friction is wheels starts to become significant. This will stop the plane from moving no matter how much thrust there is fro the engines.

You see what i'm getting at?

[*Tom*]

Ignor this getting confused :$

I agree with JT

Edited December 31, 2007 by *Tom*