Long rod question

vonhelmet said:
You're wrong.

Please, let's not do this AGAIN.
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He's right.


@OP:
It depends on your definition of "won't stretch", does this mean pressure waves are permitted, and if so, do these count as movement at the other end?

Basically, it will move instantaneously, given your simpifications.
 
haha never realised they actually did it

could have been nasty if the double speed of the wheels caused the tyres to burst mind
 
Planes take of by creating a difference in air pressure between the top and bottom of the wing. If the air is still relative to the wing it wont take off. The wheels have nothing to do with it
 
Le_Petit_Lapin said:
I stated it was wrong, because it IS wrong! :)


See the plane going into the air? ;)
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I can't look now but if that's the myth busters video then i saw on tv ages ago and it was the least scientific experiment i have ever seen. The plane wasn't still relative to the ground therefore it wasn't recreating the scenario
 
Grrrrr said:
Planes take of by creating a difference in air pressure between the top and bottom of the wing. If the air is still relative to the wing it wont take off. The wheels have nothing to do with it
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eh , you havent explained anything there

the plain on the conveyor moves forwards
that creates the air pressure difference
it takes off
 
Grrrrr said:
I can't look now but if that's the myth busters video then i saw on tv ages ago and it was the least scientific experiment i have ever seen. The plane wasn't still relative to the ground therefore it wasn't recreating the scenario
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what are oyu on about , relative to the ground ? no one has mentioned that anywhere

they just mention a plane on a giant treadmill/conveyor

you said it yourself that the wheels dont matter . so how do you not realise that the only thing touching the treadmill is the wheels therefore it is no different to taking off on a proper runway
 
I don't quite understand the plane on a treadmill question. I don't understand the scenario properly.

Is the point that the treadmill turns in such a way as to exactly negate the forward motion of the plane? If so the plane will be stationary with respect to the air around it so no air is flowing above and below the wing, hence no lift and no takeoff. The treadmill will be going extremely fast though - and a lot faster than a real life's plane's undercarriage would ever reasonably expect to go.
 
WTF is with the treadmill? If a plane was on a runway with treadmills under the wheels, when the plane started moving (regardless of how fast the mills were going) it would just go forward, off the mills and down the runway.



Post above me.....................666 spooky
 
gillywibble said:
Irrespective of length?
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Yes, if we're making the assumption that the material doesn't stretch.
This can obviously never been true in the real world as it would move instantly.

From the vague bits I remember from solid state physics the speed of propagation of Phonons in a crystal is the speed of sound in that material for a real metal, so the other end would move after the length * speed of sound in the material.

PS, 0.999... = 1 as well :p
 
When you run on a treadmill you don't move from A to B you stay in the same place. Right? Therefore you are still relative to the ground
When you run on a treadmill you don't feel a breeze on your face. Right? Therefore you are not moving relative to the air.
So saying the ground is not moving relative to the air is correct. Right?

If you are not moving relative to the ground (as shown above) this means you are not moving relative to the air. If you are not moving relative to the air then the air is not flowing over the wings. If the air is not flowing over the wings you get not lift. If there is no lift you don't take off.

There proven. Right?
 
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