Mythbusters to take on "the plane and the treadmill" conundrum?

[foghorn67]

Victims of the almighty Plane on the Treadmill Thread: His
Excellency hopes that you will die honorably.
But should any of you wish to beg for mercy,
the great Physics 101 Book will now listen to
your pleas.

 

[MasonLuke]

/thread

 

[Zoblefu]

Maybe there should be a poll

 

[MasonLuke]

i guess this issue has been resolved.

:beer:

 

[Gibsons]

Originally posted by: MasonLuke
i guess this issue has been resolved.

:beer:

If you mean people got tired of arguing, then yes.

 

[randay]

the plane takes off no matter what.

 

[Ramma2]

Originally posted by: randay
the plane takes off no matter what.

Only if it was a VTOL plane.

 

[randay]

Originally posted by: Ramma2

Originally posted by: randay
the plane takes off no matter what.

Only if it was a VTOL plane.

it doesnt matter what kind of plane it is, it takes off.

 

[sao123]

Originally posted by: MasonLuke

Originally posted by: Garth

Originally posted by: smack Down

Originally posted by: unfalliblekrutch

Originally posted by: smack Down

Originally posted by: Jeff7

Originally posted by: smack Down
YOu are talking about a different problem.

The debate is if the plane takes off when the treadmill matches the wheel speed of the plane not ground speed.

Um, no?

I said that the plane speed (and thus wheel speed too, since the two are attached) = 0.8ft/sec.
I said that the treadmill speed = 0.8ft/sec.

0.8 = 0.8

By wheel speed I mean the speed of the wheel on a treadmill.

That's would mean both increase in speed infinately, because as the thread mill increased in speed to "match" the speed of the wheel spinning, then wheel speed would increase because the threadmill is going faster, which means the treadmill has to increase it's speed again to match, etc.

So?

So that is why your "interpretation" of the problem is incoherent.

Suppose everything is at rest: the plane, the wheels, the treadmill.

Then, the plane begins to propel itself forward, moving the wheels, say, 1 inch in 1 second.

If we assume that the conveyor must match this speed, then it will move also 1 inch in 1 second, in the reverse direction.

Because of the contact of the wheel with the conveyor, however, the motion of the conveyor will necessarily move the wheel an additional 1 foot in 1 second, meaning in that 1 second interval the wheel will have traveled a net 2 feet with respect to the conveyor.

But if the wheels moved 2 feet in 1 second, then the conveyor is NOT tuned to match the speed of the wheels, because it only moved 1 foot in 1 second when obviously it should've moved 2 feet. It is therefore impossible for conveyor to match the rotational speed of the wheels as they move forward.

Congratulations on being the forum's biggest moron.

In plain english, i will explain.

How does the plane move 1 inch in 1 sec? HOW? only way is by the wheels rotating. YES OR NO?. Is there any other way the plane can move 1 inch? NO. Planes moves forward 1 inch because the wheels have rotated. FACT.

Now, turn on the treadmill. Treadmill counters the rotation of the planes wheels, thus keeping the plane still. no forward movement, no lift, the plane does not take off.

:beer:

:laugh::thumbsup:

in plain english... you are wrong.

The plane does not move forward because the wheels have rotated... the plane moves forward because then engines pushed on the atmosphere. The wheels merely rotated freely because the plane moved forward. Planes take off on ski's as well as they do on wheels.

 

[Manuwell]

A plane can fly thanks to its relative speed towards air (to make a difference of pressure between both sides of the wing when it moves forward). If no relative speed towards air (unless the plane faces a huge and basically and constant horizontal wind for the time required to take off), no take off.

 

[Gibsons]

Originally posted by: Manuwell
A plane can fly thanks to its relative speed towards air (to make a difference of pressure between both sides of the wing when it moves forward). If no relative speed towards air (unless the plane faces a huge and basically and constant horizontal wind for the time required to take off), no take off.

That's correct, but the airplane on the treadmill moves forward relative to the air, so it generates lift, so it takes off.

 

[Eeezee]

Originally posted by: Manuwell
A plane can fly thanks to its relative speed towards air (to make a difference of pressure between both sides of the wing when it moves forward). If no relative speed towards air (unless the plane faces a huge and basically and constant horizontal wind for the time required to take off), no take off.

I think the problem here is interpretation for which way the treadmill is going with respect to the plane. If the plane is facing forward, then the friction between the wheel and the treadmill essentially just helps to move the plane forward. That's how a wheel works. There will be some minimal, basically negligible rotational friction present since the universe is not perfect. In this case, the plane will take off because it will have a forward acceleration and velocity due to both the engine and the treadmill. Again, you need to understand how a wheel works. The friction from the treadmill only causes the plane to accelerate forward.

Let's say the plane is facing the opposite direction. Let me just make it clear how I'm talking about; the way you normally exercise on a treadmill is considered the forward direction. The last example was the plane facing in the forward direction. Now let's have the plane facing in the backward direction. Now the friction from the treadmill causes the wheels to spin opposite in direction to the acceleration of the plane due to its engine. In other words, if you can get the treadmill moving just right, the plane will not move, and thus it will not be able to take off. Without some forward velocity, there is no air moving across the wings, and thus there is no lift.

 

[LeiZaK]

Originally posted by: Gibsons

Originally posted by: Manuwell
A plane can fly thanks to its relative speed towards air (to make a difference of pressure between both sides of the wing when it moves forward). If no relative speed towards air (unless the plane faces a huge and basically and constant horizontal wind for the time required to take off), no take off.

That's correct, but the airplane on the treadmill moves forward relative to the air, so it generates lift, so it takes off.

Isn't the point of the whole thing that the plane does NOT move relative to the air because of the countering force of the treadmill?

 

[LeiZaK]

Originally posted by: Eeezee

Originally posted by: Manuwell
A plane can fly thanks to its relative speed towards air (to make a difference of pressure between both sides of the wing when it moves forward). If no relative speed towards air (unless the plane faces a huge and basically and constant horizontal wind for the time required to take off), no take off.

I think the problem here is interpretation for which way the treadmill is going with respect to the plane. If the plane is facing forward, then the friction between the wheel and the treadmill essentially just helps to move the plane forward. That's how a wheel works. There will be some minimal, basically negligible rotational friction present since the universe is not perfect. In this case, the plane will take off because it will have a forward acceleration and velocity due to both the engine and the treadmill. Again, you need to understand how a wheel works. The friction from the treadmill only causes the plane to accelerate forward.

Let's say the plane is facing the opposite direction. Let me just make it clear how I'm talking about; the way you normally exercise on a treadmill is considered the forward direction. The last example was the plane facing in the forward direction. Now let's have the plane facing in the backward direction. Now the friction from the treadmill causes the wheels to spin opposite in direction to the acceleration of the plane due to its engine. In other words, if you can get the treadmill moving just right, the plane will not move, and thus it will not be able to take off. Without some forward velocity, there is no air moving across the wings, and thus there is no lift.

I just got a little dumber

 

[Gibsons]

Originally posted by: LeiZaK

Originally posted by: Gibsons

Originally posted by: Manuwell
A plane can fly thanks to its relative speed towards air (to make a difference of pressure between both sides of the wing when it moves forward). If no relative speed towards air (unless the plane faces a huge and basically and constant horizontal wind for the time required to take off), no take off.

That's correct, but the airplane on the treadmill moves forward relative to the air, so it generates lift, so it takes off.

Isn't the point of the whole thing that the plane does NOT move relative to the air because of the countering force of the treadmill?

No, the point is that the treadmill exerts little to no force on the airplane because of the wheels.

 

[LeiZaK]

Originally posted by: Gibsons

Originally posted by: LeiZaK

Originally posted by: Gibsons

Originally posted by: Manuwell
A plane can fly thanks to its relative speed towards air (to make a difference of pressure between both sides of the wing when it moves forward). If no relative speed towards air (unless the plane faces a huge and basically and constant horizontal wind for the time required to take off), no take off.

That's correct, but the airplane on the treadmill moves forward relative to the air, so it generates lift, so it takes off.

Isn't the point of the whole thing that the plane does NOT move relative to the air because of the countering force of the treadmill?

No, the point is that the treadmill exerts little to no force on the airplane because of the wheels.

If you put real-world limits on how fast the treadmill can spin, then yes. I choose not to, because it is not part of the problem.

 

[randay]

Originally posted by: LeiZaK

Originally posted by: Eeezee

Originally posted by: Manuwell
A plane can fly thanks to its relative speed towards air (to make a difference of pressure between both sides of the wing when it moves forward). If no relative speed towards air (unless the plane faces a huge and basically and constant horizontal wind for the time required to take off), no take off.

I think the problem here is interpretation for which way the treadmill is going with respect to the plane. If the plane is facing forward, then the friction between the wheel and the treadmill essentially just helps to move the plane forward. That's how a wheel works. There will be some minimal, basically negligible rotational friction present since the universe is not perfect. In this case, the plane will take off because it will have a forward acceleration and velocity due to both the engine and the treadmill. Again, you need to understand how a wheel works. The friction from the treadmill only causes the plane to accelerate forward.

Let's say the plane is facing the opposite direction. Let me just make it clear how I'm talking about; the way you normally exercise on a treadmill is considered the forward direction. The last example was the plane facing in the forward direction. Now let's have the plane facing in the backward direction. Now the friction from the treadmill causes the wheels to spin opposite in direction to the acceleration of the plane due to its engine. In other words, if you can get the treadmill moving just right, the plane will not move, and thus it will not be able to take off. Without some forward velocity, there is no air moving across the wings, and thus there is no lift.

I just got a little dumber

and it doesnt get much dumber than that.

 

[maziwanka]

i think about it like this: when i am running on a treadmill i do not feel the air rushing past me like i do when i run around a track. or what about when a car is on a dyno? there is no air moving past the car. if you need air to move over the wing in order to generate lift, then the plane wont take off on a treadmill that exactly counters the landing gears moving forward.

 

[Gibsons]

Originally posted by: maziwanka
i think about it like this: when i am running on a treadmill i do not feel the air rushing past me like i do when i run around a track. or what about when a car is on a dyno? there is no air moving past the car. if you need air to move over the wing in order to generate lift, then the plane wont take off on a treadmill that exactly counters the landing gears moving forward.

In both cases, you're relying on the propulsion from contact (friction) with the ground. The plane's propulsion doesn't work that way.

 

[randay]

Originally posted by: maziwanka
i think about it like this: when i am running on a treadmill i do not feel the air rushing past me like i do when i run around a track. or what about when a car is on a dyno? there is no air moving past the car. if you need air to move over the wing in order to generate lift, then the plane wont take off on a treadmill that exactly counters the landing gears moving forward.

thats because youre a fat ass. airplanes dont have that problem. lose some damn weight.

 

[ElFenix]

Originally posted by: LeiZaK

Originally posted by: Gibsons

Originally posted by: LeiZaK

Originally posted by: Gibsons

Originally posted by: Manuwell
A plane can fly thanks to its relative speed towards air (to make a difference of pressure between both sides of the wing when it moves forward). If no relative speed towards air (unless the plane faces a huge and basically and constant horizontal wind for the time required to take off), no take off.

That's correct, but the airplane on the treadmill moves forward relative to the air, so it generates lift, so it takes off.

Isn't the point of the whole thing that the plane does NOT move relative to the air because of the countering force of the treadmill?

No, the point is that the treadmill exerts little to no force on the airplane because of the wheels.

If you put real-world limits on how fast the treadmill can spin, then yes. I choose not to, because it is not part of the problem.

exactly. if you don't put limits on it, the wheels will eventually overheat, the bearings will seize, and the whole thing will catch on fire, melting the plane to the treadmill. obviously, the plane cannot take off in that condition, because the FAA won't let it.

 

[91TTZ]

Originally posted by: Jeff7

I think that infinite speed of a treadmill would create other problems, since at that speed, its atoms might turn into energy, and then you'd have a massive blast of gamma radiation, with a large crater. I guess all of the airplane would become airborne, since it would be completely vaporized by the superluminal treadmill.

2nd that.

Superluminal treadmill FTW.

 

[91TTZ]

What if there was a leprechaun standing on the treadmill? Will the plane take off then?

 

[Fenixgoon]

people, the plane takes off. the power from the plane's engines is not transmitted to the ground, like a car's is. essentially, the plane taking off is independent of the ground below it, and solely dependent on the thrust provided by its engines. if you drop a plane from a blimp (just imagine it for a second) and start the engines, the plane will fly... but if you drop a car, it will still fall because a car is relying on its contact with the ground, while a plane is not.

also think about a bottlerocket - they'll still fly even though they dont have wheels and you can set them off as they rest on the ground.

 

[GuitarDaddy]

I have to stop reading this thread

I,m loosing faith in human intellegence. I truly hope many of the posters here are 13, drunk, or joking. Or all of the above