so your saying the tires will never move faster than the belt? welcome to the no-fly side!

 

The wheels always will be accelerating to a speed faster than the conveyer belt, but the conveyer belt will always be accelerating just as fast in the opposite direction. It is a loaded question and a darn good one.

But I have to be on the "No Fly" zone because eventually the wheels will be spinning so fast that the axle friction alone will be absorbing all of the plane's thrust, and so the acceleration will stop and the plane will be stationary at that point.

I love this question... The guys over at www.USPoliticsOnline.com had a ball with it too.

 

I voted, but if I remeber correctly, Hoss changed his mind a few pages in

And I was hoping this plane thing would just slowly fade into the abyss...

 

Why do you feel the wheels would be absorbing all the thrust? When the aircraft reaches a certain speed it will begin to lift off the conveyor. What this means is say the plane requires 150 mph to lift off. The wheels would be travelling at 300 mph. That is all it boils down to. Again, since there is no thrust being applied to the wheels or conveyor, the conveyor does not mean anything other than the speed of the wheels.

 

*** 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?

The question is written correctly. The conveyor will match the speed of the wheels. The engines are not connected to the wheels. The wheels simply "eliminates" friction. The engines are thrusting against the air the plane will move and take off.

 

THERE YA GO!!!!!
Dang I love a good debate!!

 

Guys, please do not keep opening seperate threads. This is the one brain teaser thread that is allowed. Others have been merged.

 

Jack's right ..... it's confusing enough to keep track of this one let alone starting 2-3 others simply to prove that the YES-FLY guys are right !!!

I like the idea of the poll !!!

PISTOL

 

the belt will also be going 300 mph and the plane will be stationary

 

Okay, derek, use your analogy. You are 100% right. It is like putting a microphone against the speaker. The conveyor cancels out the wheels. Now all you have to do is walk up the the speaker and push it. It will move. An outside force has moved the speaker.

The point is the is ANOTHER force affecting the plane senerio that you are not taking into account. The thust of the engines against the air.

 

ok, just answer this one question, if the belt is moving and the engines are off what is the plane gonna do?

 

The belt will stop? The belt is not in control. It is designed to match the speed of the wheels.

 

ok if u used your rules yes, but in the real world the plane will move w/ the belt meaning the belt can hold the plane back from accelerating

 

whats the linear speed of the conveyor when compared some point on the ground? ZERO. all it does is rotate and therefore creates a belt speed directly underneath the wheels; its this speed we probably all assume is the speed that matches the plane speed instantaneously.

if the plane (and its wheels) are moving forward relative to the ground (which it needs to fly; actually it needs airspeed not ground speed so i dont want to rewrite this for air speed, but i will if you want me to) the problem says the conveyor matches that speed. but how can it match the linear speed of the aircraft if itself (the conveyor) cannot have a linear speed? the conveyor is motionless in the linear direction in the grand scheme of the problem (the two axes of the conveyor never move relative to the ground), and the plane is not motionless in the linear direction.

if the plane and its wheels are moving X mph forward in relation to the ground, the conveyor will match this speed but that speed is matched at the belt directly underneath the wheels.

if the belt is moving from behind the plane (the belt underneath the wheels is moving the same direction as the wheels), it would still move because the plane and its wheels relative to the ground are moving so the conveyor is going to match that speed; it would appear that your runway is not moving to you sitting in the plane, but in relation to an arbitrary point on the ground it is.

if the conveyor is coming at you (the belt underneath the wheels is moving in the opposite direction as the wheels), it still moves because the plane and its wheels relative to the ground are moving forward at some velocity, the belt underneath the wheels is moving that same velocity just opposite direction, and since the wheels are free to ROTATE (even though they have forward linear speed, the rotation is reversed) in any direction without any bearing on the plane speed, it takes off.

pick one arbitrary point and relate all velocities to this one point and you will see the plane still moves forward no matter what.

a few of my last posts i said the plane would take off if the conveyor was rotating one way, and it wouldnt take off if it were rotating the other way. i take that all back. the plane flies no matter what. and ultimately i believe that is why the problem is written the way it is, to make the reader see opposite and believe everything cancels out. not true.

IT FLIES and i continue to build more of the best selling, single engine aircraft out there.

 

If anyone needs more of an explianation than what pgilles just gave go ahead and stab yourself in the neck with a pencil.