What's really sad (for the "can't fly" crowd), though, is that even a car, who IS powered through the tires, will move forward on the conveyor belt... His speedometer won't accurately show how fast he's moving, though, 'cause his tires will have to spin twice as fast to obtain the same true speed.

Case in point: your speedo is just a calculation of how fast your tires are rotating. It isn't necessarily reflect how fast you are actually moving. Do a burnout, and your speedo says you're going 30+ mph. The reality of it is, you aren't moving at all.

Moving is actual moving. Not angular velocity of tires. So if the plane is MOVING, then it is ACTUALLY MOVING... Guess the "can't fly" crowd doesn't understand what "Moving" means...

I believe an ostrich actually CAN take off at 120mph.

Here's where you aren't getting it.

The treadmill is moving at 160mph relative to the plane's speed. The treadmill is moving at 80mph relative to you standing on the ground next to it.

I'd like to see Mythbusters take that one on!

I simply CANNOT believe that yet another thread on this issue has surfaced! I bet that even after Mythbusters CONFIRMS that the plane will fly, the "can't fly" crowd will find some problem with their methods in order to hold fast to their belief that the plane won't fly.

The funny part is, even if the Mythbusters set the treadmill faster than the planes takeoff ground speed, the can't fly crowd would freak and say that it wasn't a valid test because the treadmill was moving too fast

...and created a vacuum behind the plane which propelled it down the runway - which otherwise would not occur if the treadmill would precisely match the speed of the craft.

I'm always kind of shocked that many people have so much faith in this show "Mythbusters".

It is entertainment. It is NOT science.

They have been wrong and will continue to be wrong on things.

And... I'm not talking about the plane/treadmill thing. I am just talking about the show "Mythbusters" in general.

I don't know for certain, but it'd be a helluva' show!

I get trolled for saying that the plane will take off.

Kick-ass!

Who said I can't fly?

You are oversimplifying things. The classic Newtonian mechanics stops working as soon as the treadmill is powered.
The plane will stay stationary until the wheels reach relativistic angular velocity, then it will disappear and pop up at a random point of the Universe.

Finally, an answer that makes sense.

The wheels don't provide ANY forward momentum to the plane. If the jet engines are going, the plane will move forward and take off no matter what's under the wheels. Think about a seaplane taking off against the current of a river, its no problem at all. Ever wonder why the jet dragsters don't do burnouts at the drag strip? Hello?

The "It won't fly" crowd is probably the same crowd who bought all of Suzanne Sommers' thigh masters... Mom used to say, "the world needs dumb people to make the rest of us look smart."

My official response is that there is not enough information in the question

Quote:

A plane is standing on a runway that can move (like a giant conveyor
belt). This conveyor has a control system that tracks the plane's
speed and tunes the speed of the conveyor to be exactly the same (but
in the opposite direction).

Will the plane be able to take off?

Since the plane is standing on the runway the net movement would be 0 therefore the plane would not take off.

If the question assumes that the plane makes an effort to move forward and the treadmill matches spead of the fusalage..sp? then the plane would take off. The best explanation for this would be that there is a rope attached to the back of the plane that runs to a pulley that attaches to the front of the treadmill as plane moves forward the treadmill would turn back at exact speed that the plane moves forward.

If the treadmill is matching the speed of the plane based on the speed of the tires then the plane would remain static and would not take off .

How can the plane have any speed to match if it's stationary?

Your rope-driven-conveyor is bogus, as that totally changes the scenario and adds a whole lot more friction to overcome. Besides, a traditional drivetrain in a piston-prop might work to drive a conveyor, but how would you accomplish that with a turboprop or jet? A big honkin windmill? still wouldn't keep the plane on the ground.

I was using the rope driven conveyor as an example much like the touch and go and all the toehr stuff people have been using as examples.

Very true - it does not say whether the conveyor belt (or treadmill or whatever) matches the planes speed relative to the ground or to itself.

Neither matters.

Here you go.....

583 pages and over 2 years arguing about the plane on a conveyor belt...

http://forum.physorg.com/index.php?showtopic=2417&st=0

Actually, it does.

If the plane's speed is relative to the belt, the ONLY speed that can be matched by the belt is zero. Otherwise, it's caught in a infinite speed curve up (meaning the belt can't match it). Example - if the plane is moving 2mph relative to the belt, the belt has to go 2mph in the opposite direction - but then the plane is actually moving at 4mph relative to the belt - then the belt has to go 4mph...but then the plane is going 8mph relative to the belt...and so on and so on.

If the plane's speed is relative to the ground, then it takes off no problem, and the belt can match it's speed. In which case, the belt has absolutely no bearing on the plane's movement.

If speed is relative to the belt, then the plane moves forward on the belt at a rate of 10 knots over the belt, the belt spins backwards at 10 knots, and the plane moves forward just the same. That in turn increases the relative speed of the aircraft. Situation: entirely impossible. Even if it were, the plane would still take off.

You're right when you say the only speed the belt could match was zero.

Still doesn't matter, the plane takes off.

::ETA:: even with constant exponential acceleration of the belt, the plane can overcome the minimal friction of the conveyor under its free-spinning wheels.

Exactly.

Why is it so hard to comprehend that the only speed that matters is the speed of the plane relative to air? Not to the observer, not to the treadmill, not to the ground, not to your uncle, nothing else, but the AIR.

if the speed of the treadmill is the same as the speed that the tires are spinning then the plane will not move if the plane is moving forward then the tires are spinning faster than the treadmill is going