Mythbusters punk'd whole internet

Page 2 - Seeking answers? Join the AnandTech community: where nearly half-a-million members share solutions and discuss the latest tech.

RapidSnail

Diamond Member
Apr 28, 2006
4,257
0
0
Simple solution:

If the speed of the treadmill matches the speed of the wheels, the plane can not take off.

If the speed of the treadmill matches the speed of the plane, the plan can take off.
 

FoBoT

No Lifer
Apr 30, 2001
63,084
15
81
fobot.com
Originally posted by: RapidSnail
Simple solution:

If the speed of the treadmill matches the speed of the wheels, the plane can not take off.

If the speed of the treadmill matches the speed of the plane, the plan can take off.

no, see dullards tether example
a belt can't tether wheels
 

mobobuff

Lifer
Apr 5, 2004
11,099
1
81
Originally posted by: RapidSnail
Simple solution:

If the speed of the treadmill matches the speed of the wheels, the plane can not take off.

If the speed of the treadmill matches the speed of the plane, the plan can take off.

FAIL!

When's this coming on?
 

her209

No Lifer
Oct 11, 2000
56,336
11
0
Originally posted by: mordantmonkey
the thread is obviously doomed because the conveyor belt will have to keep moving faster and faster to keep the plane stationary in order to keep it from taking off.
WRONG!

The speed of the conveyor belt has no effect on the plane (in the original question) because the wheels are free spinning thus the plane WILL take off.
 

RapidSnail

Diamond Member
Apr 28, 2006
4,257
0
0
Originally posted by: FoBoT
Originally posted by: RapidSnail
Simple solution:

If the speed of the treadmill matches the speed of the wheels, the plane can not take off.

If the speed of the treadmill matches the speed of the plane, the plan can take off.

no, see dullards tether example
a belt can't tether wheels

Oh, I guess I missed something. I thought that the treadmill speed was supposed to directly match the plane's forward motion. The plane can take off if that's the case. Dullard's post doesn't mention anything about tethering, unless it has a meaning I don't understand.
 

mobobuff

Lifer
Apr 5, 2004
11,099
1
81
I can see how it's going to work...

They set it up the best they can, the plane takes off every time, they explain that it's a hypothetical scenario and they can't satisfy it fully with their contraptions because they cannot accelerate the belt quickly enough. And then after all is said and done, they'll explain that the plane would still take off even if the treadmill could go as fast as it wanted.

Maybe they'll make a cool 3D demo.
 

RapidSnail

Diamond Member
Apr 28, 2006
4,257
0
0
Originally posted by: mobobuff
Originally posted by: RapidSnail
Simple solution:

If the speed of the treadmill matches the speed of the wheels, the plane can not take off.

If the speed of the treadmill matches the speed of the plane, the plan can take off.

FAIL!

When's this coming on?

I don't understand.

Theoretically, if you hold a plane stationary on a treadmill and the treadmill moves backwards at 100, the wheels will be moving at 100 in the other direction. If the treadmill moves at 100 and the plane moves forward at 100, the wheels move at 200. What's wrong with that?
 

randay

Lifer
May 30, 2006
11,018
216
106
Originally posted by: RapidSnail
Originally posted by: FoBoT
Originally posted by: RapidSnail
Simple solution:

If the speed of the treadmill matches the speed of the wheels, the plane can not take off.

If the speed of the treadmill matches the speed of the plane, the plan can take off.

no, see dullards tether example
a belt can't tether wheels

Oh, I guess I missed something. I thought that the treadmill speed was supposed to directly match the plane's forward motion. The plane can take off if that's the case. Dullard's post doesn't mention anything about tethering, unless it has a meaning I don't understand.

no actually you are right, except in the "treadmill matches the speed of the wheels" scenario, its only correct because the only time that the treadmill can match the speed of the wheels is at zero. which makes it more of a trick question then a practical one.
 

RapidSnail

Diamond Member
Apr 28, 2006
4,257
0
0
Originally posted by: randay
Originally posted by: RapidSnail
Originally posted by: FoBoT
Originally posted by: RapidSnail
Simple solution:

If the speed of the treadmill matches the speed of the wheels, the plane can not take off.

If the speed of the treadmill matches the speed of the plane, the plan can take off.

no, see dullards tether example
a belt can't tether wheels

Oh, I guess I missed something. I thought that the treadmill speed was supposed to directly match the plane's forward motion. The plane can take off if that's the case. Dullard's post doesn't mention anything about tethering, unless it has a meaning I don't understand.

no actually you are right, except in the "treadmill matches the speed of the wheels" scenario, its only correct because the only time that the treadmill can match the speed of the wheels is at zero. which makes it more of a trick question then a practical one.

In the treadmill = wheels scenario, the only way for there to be a net of zero would be if the plane was held stationary by a cable or something, right? There is no way for there to be net zero motion if the planes engines move and the treadmill = wheels, correct?
 

mobobuff

Lifer
Apr 5, 2004
11,099
1
81
Originally posted by: RapidSnail
Originally posted by: mobobuff
Originally posted by: RapidSnail
Simple solution:

If the speed of the treadmill matches the speed of the wheels, the plane can not take off.

If the speed of the treadmill matches the speed of the plane, the plan can take off.

FAIL!

When's this coming on?

I don't understand.

If the treadmill moves at 100 and the plane moves forward at 100, the wheels move at 200. What's wrong with that?

Nothing wrong with that, you are absolutely correct. Ignoring real-world things like the bearings of the wheels melting or the landing gear tearing off from high frequency vibration, the plane can take off even if the conveyor moves at near light speed.
 

RapidSnail

Diamond Member
Apr 28, 2006
4,257
0
0
Originally posted by: mobobuff
Nothing wrong with that, you are absolutely correct. Ignoring real-world things like the bearings of the wheels melting or the landing gear tearing off from high frequency vibration, the plane can take off even if the conveyor moves at near light speed.

What did I get wrong then? :)
 

RapidSnail

Diamond Member
Apr 28, 2006
4,257
0
0
Originally posted by: Citrix
<<<< RUNS OUT OF THREAD YELLING AND SCREAMING LIKE RICHARD PRYOR ON FIRE!!!!

It's impossible to escape this thread since it is on a treadmill that matches your forward motion exactly. Which begs the question, is stop, drop, and roll still feasible?

;):p
 

mordantmonkey

Diamond Member
Dec 23, 2004
3,075
5
0
Originally posted by: her209
Originally posted by: mordantmonkey
the thread is obviously doomed because the conveyor belt will have to keep moving faster and faster to keep the plane stationary in order to keep it from taking off.
WRONG!

The speed of the conveyor belt has no effect on the plane (in the original question) because the wheels are free spinning thus the plane WILL take off.

your assuming the wheels are perfectly frictionless?

it was a joke anyway. i was referencing the doomed thread and goading argument in the same breath

but if you insist...
if wheels have friction and belt can move infinitely fast then the plan will not move.
if they are frictionless wheels then the plan will take off regardless of whether the belt is magical or not.

however both belt and wheels being of this world, yes the plane will take off.

i never understood the problem with understanding this. it really boils down to... does the plane move, or can you stop a plane on wheels from moving by putting it on a treadmill. only in one strange outlandish situation is this possible.
 

Darwin333

Lifer
Dec 11, 2006
19,946
2,329
126
Originally posted by: mordantmonkey
the thread is obviously doomed because the conveyor belt will have to keep moving faster and faster to keep the plane stationary in order to keep it from taking off.

Why would the conveyor belt's speed be a factor in the plane taking off? As long as the wheel/axle assembly can take the increased speed the speed of the conveyor has nothing to do with the speed of the air going over the wings and the wheels don't provide propulsion.
 

mordantmonkey

Diamond Member
Dec 23, 2004
3,075
5
0
Originally posted by: Darwin333
Originally posted by: mordantmonkey
the thread is obviously doomed because the conveyor belt will have to keep moving faster and faster to keep the plane stationary in order to keep it from taking off.

Why would the conveyor belt's speed be a factor in the plane taking off? As long as the wheel/axle assembly can take the increased speed the speed of the conveyor has nothing to do with the speed of the air going over the wings and the wheels don't provide propulsion.

exactly. i'm not saying just the belt's speed, i'm saying the belt's speed ability in relation to the wheels ability to cope with that speed.
any friction the wheels have (internally axle,hub) will allow the treadmill's movement to be exerted against the plane.

just to clarify the plane will take off. barring a completely unrealistic scenario.

completely unrealistic... kind of relative when your talking about a plane on a conveyor belt trying to take off.
 

mobobuff

Lifer
Apr 5, 2004
11,099
1
81
Originally posted by: mordantmonkey
Originally posted by: her209
Originally posted by: mordantmonkey
the thread is obviously doomed because the conveyor belt will have to keep moving faster and faster to keep the plane stationary in order to keep it from taking off.
WRONG!

The speed of the conveyor belt has no effect on the plane (in the original question) because the wheels are free spinning thus the plane WILL take off.

your assuming the wheels are perfectly frictionless?

it was a joke anyway. i was referencing the doomed thread and goading argument in the same breath

but if you insist...
if wheels have friction and belt can move infinitely fast then the plan will not move.
if they are frictionless wheels then the plan will take off regardless of whether the belt is magical or not.

however both belt and wheels being of this world, yes the plane will take off.

i never understood the problem with understanding this. it really boils down to... does the plane move, or can you stop a plane on wheels from moving by putting it on a treadmill. only in one strange outlandish situation is this possible.

The original question stated that the conveyor matches the speed of the plane. The plane will take off long before the conveyor reaches ridiculous speeds. Most commercial jets reach takeoff speed at about 180mph.
 

AlienCraft

Lifer
Nov 23, 2002
10,539
0
0
Originally posted by: RapidSnail
Originally posted by: Citrix
<<<< RUNS OUT OF THREAD YELLING AND SCREAMING LIKE RICHARD PRYOR ON FIRE!!!!

It's impossible to escape this thread since it is on a treadmill that matches your forward motion exactly. Which begs the question, is stop, drop, and roll still feasible?

;):p
NOW THAT's Funnay!

 

Cerpin Taxt

Lifer
Feb 23, 2005
11,940
542
126
Originally posted by: RapidSnail
In the treadmill = wheels scenario, the only way for there to be a net of zero would be if the plane was held stationary by a cable or something, right? There is no way for there to be net zero motion if the planes engines move and the treadmill = wheels, correct?
Yes, but not because of some physical impossibility, but instead because of a rather trivial incoherency in the premise. In other words, there's nothing stopping the plane from moving forward, but as soon as it does, it is no longer true that "treadmill = wheels" with regard to speed. In still other words, it's impossible to create a feedback loop wherein the "speed of the treadmill = the speed of the wheels" under every circumstance.

There's nothing stopping the plane from moving forward, and thus accelerating the wheels, but once that happens you initiate an infinitely recursive self-oscillation where the treadmill must accelerate to match the new speed of the wheels, which in turn accelerates the wheels even more, which then demands that the treadmill accelerates to match the new speed of the wheels, which in turn accelerates the wheels even more, which then demands that the treadmill accelerates to match the new speed of the wheels, which in turn accelerates the wheels even more, which then demands that the treadmill accelerates to match the new speed of the wheels, which in turn accelerates the wheels even more, which then demands that the treadmill accelerates to match the new speed of the wheels, which in turn accelerates the wheels even more, which then demands that the treadmill accelerates to match the new speed of the wheels, which in turn accelerates the wheels even more, which then demands that the treadmill accelerates to match the new speed of the wheels, which in turn accelerates the wheels even more, which then demands that the treadmill accelerates to match the new speed of the wheels, which in turn accelerates the wheels even more, which then demands that the treadmill accelerates to match the new speed of the wheels, which in turn accelerates the wheels even more, which then demands that the treadmill accelerates to match the new speed of the wheels...


Get the idea? :)