*** Brain Teaser ***

Imagine an airplane is on the beginning of a massive conveyor belt, as wide and as long as a runway, and intends to take off. The conveyer belt is designed to exactly match the speed of the wheels at any given time, moving in the opposite direction of rotation.
There is no wind.

Can the plane take off?

 

Nope.

No moving air, no lift.


phox

 

Nope it needs air passing over the wings at a certain velocity to achieve lift. Just the wheels turning ain't gonna make er fly Wilbur

 

i wouldn't think so... technically the plane is not moving.... doesn't the air cause the lift on the wings?

 

Yes....The Plane does not need air, It has jet turbines and is not powerd by the wheels, So technichly the plane can take off..

 

Been over to SP.com??

Ed

 

SHHHH!

 

from someody who fly's for a living, no wind over the wings, no lift. i wouldn't want to be on that plane.

 

Really?I asked both my dad and brother in law who both fly...Both of them said it would take off because of foward propultion...

 

It would take off in half the length that it would normally take without the conveyor belt.

chaikwa.

 

well if you have no wind over the wings you would have no lift. if you had the wind from the propulsion then yes, granted you had the speed for what ever plane you had. but for no wind over the wings it would be like a rock going through the air.

 

this question has got my mind thinking. read the question again and it seems that the only thing different is the wheels spinning backwards but everything else is the same, yes it would go.

 

Of course the plane will take off. The plane's thrust is in relationship to the plane and the air around it. The tires are spinning at 0 MPH just prior to touchdown and over 100 MPH just after touchdown with the plane's speed not changing but a little bit at that touchdown point.

So, the plane will take off but the wheels will either be going 0 MPH or twice as fast as normal take off speed, depending on how you understand the conveyor belt to be moving in the puzzle.

Imagin wearing roller skates on one of those people movers (conveyor belt) they have at some airports. If you just stand there, the wheels are going 0 MPH in relationship to the belt but you are moving the speed of the belt. If it was a skinny belt and there were people on each side of it that were not on the belt and were pulling you along, it wouldn't matter in which direction or at what speed the belt was moving, as you would be going the speed of your helpers and in their direction. (Yeah, we are all balanced on roller skates, right?)

 

OK, Here is another one: If a bulldozer is moving at a speed of 5mph the top of the track is moving at 10mph. How fast is the track on the bottom going?

 

So the airplane is stationary on a conveyer belt. The belt is moving back as fast as the plane is moving forward, so the plane is basically on something like a dyno. So the plane is stationary.

How is there lift if the airplane is stationary? There isn't. There can't be.

Can an airplane take off with no lift? No it can't.

Problem solved.


10 MPH. (Did you type that one wrong, or are you being sarcastic?)