Can the plane take off?

[Da1andonly]

that only means we can't agree that the first two quotes are true!

[RednaZ]

I read a bit of one of those links someone posted and I found this to be a useful bit of information. Dr. Paul J. Camp, Physics Department, Spelman College says: actually I forgot what it was he said exactly, but the engines are pushing the plane forwards and in turn the plane tries to pull the wheels forward. If the conveyer belt keeps matching the speed of the wheels, the wheels will simply start sliding as soon as they reach their friction force limit and the plane moves forward.

[Fluffz]

that only means we can't agree that the first two quotes are true!

in general both together are not, but each for itself is, its impossible for the plane to start accelerating. but since this is hypothetical question there is indeed a single situation at which both arguments are valid together: its when the plane goes 600 kmh, the band speed hits lightspeed and wheel speed is lightspeed too (band speed + plane speed).

if hypothetically we would have enough energy to match wheel and band speed and the universe is set up awsome enough to avoid its own destruction by this ammout of energy the plane would melt instantly.

the wheels do not spin faster than the belt moves backwards, those 2 speeds match exact, how can the plane move forward? it cant. if it would the belt speed would not match the wheels rotation speed which is a must by definition. it cant fly and thats the only answer. if it moves forwards it melts. it can either stay still or melt. the belt moves at the same speed the wheels rotate. the plane is still. AAAAH please! THINK

everyone start agreening to me now! i offer a solutions for everyone to be right by either saying he understood that the band matches the plane's speed and the plane can fly or the band matches the wheel's rotation speed and the plane cant fly. save ur ass now and quit arguing.

[Ewan]

I think you're reading a little deep into the wording of the question Fluffz.

[Maurauth]

What is the basic physics of how a plane takes off? Does it require movement of the wheels forward? If not, then it can take off!

[HeavenSent]

All I have to say is: HeavenSent.

ph, kong the shit out of this.

LOL is this a recognition of my thread killing abilities?

[thesearcher]

I think you're reading a little deep into the wording of the question Fluffz.

I think the whole idea of a riddle is its wording, and most of you are looking at it to scientifically. Fluffz is bang on, the whole idea is the wheels speed is ALWAYS matched by the conveyor belt, there is nothing to do with friction, forces, anything like that, its a simple hyperthetcial question.

for a wheel to move forwards, it has to rotate forwards, if the conveyor belt is continually countering the wheels forward rotation, the wheel cannot move forwards! "eventually the wheel will just rotate more and more" so? the conveyor belt will then just go faster and faster and faster.

As long as the wheels are connected to the conveyor belt, the plane cannot move forwards, because the wheels cannot.

[Hero*]

yeah everyone seems to be twisting the words around in the riddle. "eventually it will hit the friction level and poof, it'll go forward!" Sorry, but thats not the point of the riddle. Like honestly give me a good reason why the plane would take off without you talkin out of your ass tryin to act like you know how an airplane operates.

[Bioture]

Ok, point out to him a plane's thrust comes from the engines, not the wheels, and he should realise his problem.

right. read second quote. thrust from the engines alone is not enough for lift off.

[Fluffz]

wheels speed is ALWAYS matched by the conveyor belt, there is nothing to do with friction

it is ONLY the friction that holds the plane back. if there were no friction the plane could start while the wheels increase speed at infinite rate. thats my guess without calculating it. i think the plane can move forward when the wheel speed is infinite, and it can definatly move forward considering the maximum speed is lightspeed. the energy required could never exist, but the riddle says it does.

[Bioture]

ok better think of it this way, when you're running on a treadmill, do you feel any wind hit your face or your body?

That wind provides the additional lift necessary to the wings for takeoff.

[Galleleo]

for a wheel to move forwards, it has to rotate forwards, if the conveyor belt is continually countering the wheels forward rotation, the wheel cannot move forwards! "eventually the wheel will just rotate more and more" so? the conveyor belt will then just go faster and faster and faster.

False. Take a cart, block the wheel so it can't rotate and then start pushing it, if you use enough force eventually the cart will move forward and the wheels will be sliding instead of rotating. Same with the plane, because the plane doesn't drive the wheels but pushes them, eventually they will just start sliding.

[AnidaLife]

First of all, Fluffz, yes the riddle is worded badly, and if you take the literal meaning, then yes, unless the plane is stationary, the tangential speed wheels will always move faster than the speed conveyor belt.

Now let's forget about that contradiction. Think of this as a regular problem instead of a trick question.

First, imagine the wheels to have perfect grip against the conveyor belt, but frictionless at their axles. This way, no matter how fast the conveyor belt is moving, it will not affect the movement of the plane. If the plane needs say 1000N of force from its engines to lift off, it will need 1000N regardless if it's on the conveyor belt or not.

This is how the wheels of a plane would work in a perfect world. In reality, it doesn't work perfectly, but it's very similar. With some friction at the wheels' axles, the plane's engines need to work just a little bit harder to overcome the friction. After that, pretty much everything works the same way as the frictionless example. The plane will still move forward relative to the ground as normal, provided the engines work a bit harder. Hence the plane still takes off.



If you didn't read what's written above, read what's written below

I really like the puller plane example provided a few posts ago. Imagine 2 planes connected head to tail with a rod that has no elastivity. The second plane is on the conveyor belt and the first is in front of it, but not on the belt. The first plane starts moving forward. It will pull the second plane forward RELATIVE TO THE GROUND regardless of the conveyor belt. This type of force applied on the second plane works the exact same way as its normal thrust. Therefore the plane will be able to move forward RELATIVE TO THE GROUND regardless, and thus taking off.

[project dragon]

I was just the messenger.

[Ewan]

right. read second quote. thrust from the engines alone is not enough for lift off.

ok better think of it this way, when you're running on a treadmill, do you feel any wind hit your face or your body?

That wind provides the additional lift necessary to the wings for takeoff.

Are you just not reading what I say, I am aware of how planes fly thank you.

The FORWARDS MOTION of the plane is provided by the engines. The running on a treadmill argument is not valid as the only thing pushing you forwards are your feet, WHICH RELY ON THE SURFACE TO PUSH YOU FORWARDS, engines on a plane aren't PUSHING AGAINST THE GROUND like your feet are.

The engines are like you running on a treadmill with a rope tied to you. This rope is tied to a car, the car drives, you move forwards.