Originally posted by: beansbaxter
Alright, this is NOT a homework question. In another thread on the Anandtech forums, I saw this mentioned deep within a thread but it was never addressed. I am still curious so I ask it here:
You have an airplane on a conveyor belt - when the airplane moves forward, the conveyor matches its speed in reverse. Can the airplane take off?
Originally posted by: kpb
That question doesn't make sense. A car which moves it's self foward using the wheels would be stationary relative to the ground if the conveyor was moving in the opposite direction at the same speed as the car is according to the speedometer. This is actually how they do a number of things on cars like testing horsepower and torque or how they figure out estimated mpg.
The problem with a plane is that the movement is generated by the jet engine or propeller and is not dependant on the wheels at all. They just support it and allow it to move foward until lift allows it to take off. So even if the conveyor belt was moving backwords the plane would still end up moving forwards and gaining speed. The wheels would just be turning twice as fast. The plane would either reach then end of the conveyor belt and crash or what ever or take off once it got enough speed. The conveyor belt wouldn't effect things at all really. The type of plane wouldn't change this at all because all planes must generate thier forward motion using an engine and not the wheels or they'd start loosing speed as soon as they took off =)
"the conveyor matches its speed in reverse"
Nope.Originally posted by: sweeper2
i don't know... seems odd.. if the tconveyor is moving as fast as the plane is going... the plane will stay stationary ... am I correct on this..?
Originally posted by: smack Down
Originally posted by: dkozloski
It makes no difference what the conveyor belt does. It is irrelevant. The belt can go forward, it can go backward, it can start and stop, it can alternate back and forth, and it makes no difference other than being an annoyance.
That is simpley wrong. By definition if the treadmill is going backwards at the same speed the wheels are turning then plane can't go anywhere.
Originally posted by: hellokeith
Airplane tires are not rated for very high speed and will self destruct due to heat. Planes can and have crashed on takeoff due to tire failures.
Originally posted by: uberman
I'm diving in. I can't take this anymore. I only read about 4 pages of the thread. Lift is created by low pressure on top of the wing. This happens because air is traveling around the wing. If the conveyor belt matches the planes speed; the plane is stationary. A stationary plane has no air traveling around the wing. There is no lift. The plane does not fly.
Did I miss something? I thought this was a no brainer.
Originally posted by: uberman
Did I miss something? I thought this was a no brainer.
Originally posted by: TheoPetro
the last posts by Erydin and uberman tell me its time for some IQ cleansing. Grab your guns boys were hunten stubborn idiots!
The plane takes off. It takes off for almost every reason previously posted. The jets push the plane. The plane moves forward. Just because its wheels are spinning doesnt mean sh!t. The plane does move relative to the air. And it moves foreward. Some people need an actual experiment to realize this because their math/analytical skills arnt up to the task. Dont get mad its true. If you actually sat down with actual numbers and modled this scenereo you would come to the conclusion that the plane takes off. If you wish to invest a year in math and physics courses so you can do this go for it. (well youll probably need 2 years of math to get through calc 1-3 and ODE)
Originally posted by: Oblivionaire
Originally posted by: TheoPetro
the last posts by Erydin and uberman tell me its time for some IQ cleansing. Grab your guns boys were hunten stubborn idiots!
The plane takes off. It takes off for almost every reason previously posted. The jets push the plane. The plane moves forward. Just because its wheels are spinning doesnt mean sh!t. The plane does move relative to the air. And it moves foreward. Some people need an actual experiment to realize this because their math/analytical skills arnt up to the task. Dont get mad its true. If you actually sat down with actual numbers and modled this scenereo you would come to the conclusion that the plane takes off. If you wish to invest a year in math and physics courses so you can do this go for it. (well youll probably need 2 years of math to get through calc 1-3 and ODE)
Yeah next thing you know the buffoons will be trying to convince us that 0.999=1