Can the plane take off?

[Jerome Scuggs]

ok, I googled it

The conveyor doesn't exert much backward force on the plane, but it does exert some. Everyone intuitively understands this. To return to the analogy in my original column, if you're standing on a treadmill wearing rollerblades while holding a rope attached to the wall in front of you, and the treadmill is switched on, your feet will initially be tugged backwards. Partly this is due to friction in the rollerblade wheel bearings, but partly--this is key--it's because the treadmill is accelerating the rollerblade wheels and in the process imparting some angular (rotary) but some linear (backward) momentum to them. You experience the latter as backward force. Eventually the treadmill reaches a constant speed and the rollerblade wheels cease to accelerate. At this point you can easily haul in the rope and pull yourself forward.

The treadmill is the runway, the airplane is the rollerblade, the the rope attached the the wall are the engines.

[Nethila]

the plane can take off. however, it wont go straight from stand-point to air. it will still need some runway in order to take off

the only way this is any efficient is to reduce the length of the runway for takeoffs. thats about it

[Fluffz]

the engines will still push air behind it - and move forward. The wheels will just move alot faster, but the plane will still take off.

But how much faster will the wheels go?

imagine the engine's forward force just a tiny bit stronger as the wheels friction's backward force. think of the engine as rare tiny pushes at the plane, after every push the belt accelerates. whenever the wheel's speed accelerates forward for 1% the belt increases accelerating backwards. making the engine more powerfull will just speed up this Process but in the end there is an equal forward an backward force to keep the plane on ground and pile up energy

edit, think of it this way: the belt is switched on first pulling the plane backwards. than you fire the engines to keep the plane in the same place. no matter how much the the belt goes or accelerates, as long as you have an equal force pushing the plane forward it stands still. think away the wheels, they disturb. the plane has no wheels, the wheels are broken the brakes are pushed.

so gg, this will destroy space time. you just figured out a way to destroy the universe.

nevermind, it can take off:

[Kolar]

Mythbusters need to get on this fast.

[thesearcher]

I understand what you are saying, but you are not reading the question right, its a hyperthetical question, whatever amount of force the plane is pushing forwards, is cancelled out by the treadmill, the whole point of the question is "if a plane cannot move forwards, can it take off?" and the answer is no.

I know what you are saying by its not a car but a plane, that it doesnt move by the wheels rotating, but on take off the wheels rotating is what lets the plane move forwards, if the treadmill is always matching the planes speed, then the plane cannot move forwards, and as such will be unable to take off.

[Aquatiq]

the whole point of the question is "if a plane cannot move forwards, can it take off?"

No, it really isn't, otherwise it'd be a stupidly easy question. But you need to look at all the info and take it for what it is, not with some attitude of what you -think- they want the answer to be.

[thesearcher]

yes, it really is.

[Aquatiq]

Anyone have any hope for this guy?

edit: ok, i'm going to try to dumb this down:
There is air all around the plane. What does the plane use to go forward on takeoff? It's thrust, from the engine, which has zero to do with the wheels. The wheels are just a means of smooth motion... they're performing the basic task of a wheel - to make something roll. The engine pushes air backward so the plane can move forward. The engine does not spin the wheels. The plane that's ALREADY IN MOTION in turn (no pun intended) spins the wheels. If the treadmill runway counteracts what the WHEELS are doing, maybe that provies a little force backward and the plane will have to work a LITTLE harder to take off, but what you end up with in essence is a plane taking off as normal with the wheels spinning twice as fast... 1x as fast for its forward motion during take off and another 1x as fast for how fast the treadmill is moving in the opposite direction.

[Stompa]

It's tricky because of the wording. The riddle says "speed of the plane's wheels." So if the speed of the wheels is counteracted by the conveyor, the plane will STILL be moving forward because of the thrust created by the engine.

However if the question were worded to show that the conveyor belt counteracted the acceleration of the plane itself (and not just the wheels), then no, the plane would not be able to move forward. Am I right on this?

Searcher is reading the question as if it were worded like the latter statement and not the former. Slow down and understand the question.

[Dack Falu]

hyperthetical question

Wrong! It's a supermegaultrathetical question!

[PH]

[Stompa]

lol diamonds are metal.

[Dack Falu]

I don't think diamonds are the hardest metal.

Thread de-railed, new topic:

What is the hardest metal, Diamonds or Dragonforce?

[geekbot]

I think there's confusion because the question doesn't make sense.

Normal situation:

• The engines provide thrust to push the plane forward.
• Forward movement causes air to move over the wings.
  Moving air over the wings provides lift to push the plane upward.
• That's it.
• The wheels don't do anything except roll- in otherwards something so that the plane isn't dragging along the ground as it takes off. A pontoon plane does the same except instead of wheels, there's a pontoon + water.

The "conveyor belt scenario" doesn't make sense because it implies that the belt moves in the opposite direction of the wheels pushing. But the wheels aren't pushing. The wheels are just rolling. So what in the world does it mean for a (I'm guessing) linear belt to move in the "opposite direction" of a rolling wheel? And even if the question means that the *linear velocity* of the belt is equal to the *linear velocity* of the wheel, it still doesn't make sense because it means the wheels are basically dragging forward at a speed equal to the spinning wheel's linear velocity (or some other random speed because the magic belt is "counteracting" the spin of the wheel).

What the heck?

Next question.

[Dameon Angell]

If the treadmill matches the speed of the wheels at all times the airplane can't get any traction to fly forward.