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

[Cerpin Taxt]

Originally posted by: smack Down

No as stated the treadmill matches the speed of the object on the treadmill. It does not match the ground speed of the object.

Yes, it does. You need a common reference from which to measure the speeds of each: the plane and the treadmill surface. The ground is the obvious reference.

If you put a plane on a treadmill and the planes engines are off do you really think it is just going to sit there.

Do you agree that were the nose of the plane tied to an immovable post in front of the treadmill, the plane would remain stationary while the treadmill moved underneath it?

 

[Zenmervolt]

Originally posted by: smack Down

Originally posted by: Zenmervolt

Originally posted by: smack Down

Originally posted by: Zenmervolt

Originally posted by: dmw16
It amazes me that people are dumb enough to think a plan can fly because it's wheels are turning at 300mph.

The plane flies becauase it moves forwards at exactly the same speed as it would on a normal runway.

It amazes me that people are dumb enough to believe that it wouldn't move.

ZV

The question states the plane wouldn't move. It amazes me that people are to dumb to read the question and instead just make up what ever question they want to answer.

The question, as stated, is impossible and therefore in error and irrelevant. Adjusting the question to be physically possible results in the aircraft flying. Furthermore, the question does NOT say that the aircraft remains stationary. The question only specifies that the treadmill matches the speed of the aircraft (in some cases, it says that the treadmill matches the rotational speed of the wheels).

As I have pointed out already, even if the treadmill matches the airplane's normal groundspeed, or even the wheel's rotational speed, the plane will still move forward.

ZV

You still have not demostrated how the original problem is impossible.

Sure in your fanacy world were wheels don't require force to spin it is impossible but that isn't the case in the real world.

In the real world, the force required to spin a wheel is negligible compared to the thrust generated by the engine.

But I give up on you. It's true what they say about arguing with certain people. They drag you down to their level and beat you with experience.

ZV

 

[Zenmervolt]

Originally posted by: smack Down

Originally posted by: Zenmervolt

Originally posted by: smack Down

Originally posted by: Zenmervolt

Originally posted by: smack Down
You can push any object forward on a treadmill at constant speed. If the treadmill is going to match the speed the object moves on it then you can never move the object.

Wrong. There is insufficient friction in the wheels to cause this. As stated, if the treadmill matches the object's forward speed, the wheels simply spin twice as fast for a given groundspeed.

ZV

No as stated the treadmill matches the speed of the object on the treadmill. It does not match the ground speed of the object. Otherwise the car would not have moved.

As long as the wheel are spinning a force is going to be applied to the axel that is porpotional to the speed the wheel is spinning.

Think about it.

If you put a plane on a treadmill and the planes engines are off do you really think it is just going to sit there.

The drag of the landing gear is infinitesimally small. Not enough to consider when compared to the thrust of the engine. If the engine is off, the drag of the landing gear is enough to cause the plane to "ride" the treadmill because there are no other forces acting at the moment. Once the engine is running, it becomes by far the dominant force, easily overcoming the drag of the landing gear. If the engine couldn't overcome the drag of the landing gear, the airplane wouldn't be able to take off even from a normal runway.

ZV

The size of the forces doesn't matter because the treadmill can increase speed infinitly so it can apply an infinite amount of force.

*sigh*

Please don't vote. Or breed.

ZV

 

[Queasy]

LMAO - I REALLY didn't intend on this turning into YET ANOTHER rehashing of this discussion.

 

[AbsolutDealage]

Originally posted by: smack Down

If you put a plane on a treadmill and the planes engines are off do you really think it is just going to sit there.

If there is no friction.... then yes, it will just sit there.

 

[BeauJangles]

I don't see why they would tackle this, it isn't a myth. Assuming no friction, and assuming the speed of the treadmill doesn't go to infinity (as it does in some statements of the problem), the plane will take off. It's fact.

If they're going to investigate this, they should also look at whether objects dropped off a table will fall to the ground.

 

[smack Down]

Originally posted by: Zenmervolt

Originally posted by: smack Down

Originally posted by: Zenmervolt

Originally posted by: smack Down

Originally posted by: Zenmervolt

Originally posted by: smack Down
You can push any object forward on a treadmill at constant speed. If the treadmill is going to match the speed the object moves on it then you can never move the object.

Wrong. There is insufficient friction in the wheels to cause this. As stated, if the treadmill matches the object's forward speed, the wheels simply spin twice as fast for a given groundspeed.

ZV

No as stated the treadmill matches the speed of the object on the treadmill. It does not match the ground speed of the object. Otherwise the car would not have moved.

As long as the wheel are spinning a force is going to be applied to the axel that is porpotional to the speed the wheel is spinning.

Think about it.

If you put a plane on a treadmill and the planes engines are off do you really think it is just going to sit there.

The drag of the landing gear is infinitesimally small. Not enough to consider when compared to the thrust of the engine. If the engine is off, the drag of the landing gear is enough to cause the plane to "ride" the treadmill because there are no other forces acting at the moment. Once the engine is running, it becomes by far the dominant force, easily overcoming the drag of the landing gear. If the engine couldn't overcome the drag of the landing gear, the airplane wouldn't be able to take off even from a normal runway.

ZV

The size of the forces doesn't matter because the treadmill can increase speed infinitly so it can apply an infinite amount of force.

*sigh*

Please don't vote. Or breed.

ZV

Awah how cute have to resort to more lame persional attacks.

 

[AbsolutDealage]

Originally posted by: Queasy
LMAO - I REALLY didn't intend on this turning into YET ANOTHER rehashing of this discussion.

LOL, I was thinking the same thing myself. Oh well, it's one of those things that always causes an argument.

 

[Rob9874]

Originally posted by: Garth
Do you agree that were the nose of the plane tied to an immovable post in front of the treadmill, the plane would remain stationary while the treadmill moved underneath it?

I do, that's a good analogy. And then, would you agree if someone pulled that post forward, it would not also pull the plane forward, even though the treadmill was matching the speed of its wheels?

 

[smack Down]

Originally posted by: Rob9874

Originally posted by: Garth
Do you agree that were the nose of the plane tied to an immovable post in front of the treadmill, the plane would remain stationary while the treadmill moved underneath it?

I do, that's a good analogy. And then, would you agree if someone pulled that post forward, it would not also pull the plane forward, even though the treadmill was matching the speed of its wheels?

The plane can't move forward if the treadmill is matching the speed of the wheels. It is impossible to have movement under such a case.

 

[dmw16]

The only speed that matters to making a plane takeoff is the speed of the air relative to the wing. So if there is no AIRSPEED there is no lift. That is it. You could be moving the treadmill at 1000mph, but if there air is not moving relative to the aircrafts wing it WILL NOT TAKE OFF!

 

[Rob9874]

Originally posted by: smack Down

Originally posted by: Rob9874

Originally posted by: Garth
Do you agree that were the nose of the plane tied to an immovable post in front of the treadmill, the plane would remain stationary while the treadmill moved underneath it?

I do, that's a good analogy. And then, would you agree if someone pulled that post forward, it would not also pull the plane forward, even though the treadmill was matching the speed of its wheels?

The plane can't move forward if the treadmill is matching the speed of the wheels. It is impossible to have movement under such a case.

How can you say that? If the treadmill is stationary, but someone is pulling to plane by a rope in front of the treadmill, how can the plane not move forward?

 

[AbsolutDealage]

Originally posted by: Rob9874
How can you say that? If the treadmill is stationary, but someone is pulling to plane by a rope in front of the treadmill, how can the plane not move forward?

Just give it up and let them lock this thread. If you really want this kind of argument, go start a fight with your nearest brick wall.

 

[smack Down]

Originally posted by: Rob9874

Originally posted by: smack Down

Originally posted by: Rob9874

Originally posted by: Garth
Do you agree that were the nose of the plane tied to an immovable post in front of the treadmill, the plane would remain stationary while the treadmill moved underneath it?

I do, that's a good analogy. And then, would you agree if someone pulled that post forward, it would not also pull the plane forward, even though the treadmill was matching the speed of its wheels?

The plane can't move forward if the treadmill is matching the speed of the wheels. It is impossible to have movement under such a case.

How can you say that? If the treadmill is stationary, but someone is pulling to plane by a rope in front of the treadmill, how can the plane not move forward?

Yes it would move forward but you would no longer be matching wheel speed. The only way for an object to be stationary on a treadmill is for the wheel speed to match the treadmill speed. The only way for an object to move forward is the wheel speed is greater then the treadmill speed.

 

[Tom]

As a "plane takes off" person now, could I get some feedback on a tangentental issue ?

Given the scenario, I don't see any reason to think the wheels ever rotate at all..the treadmill would never need to move relative to the wheels.

Can someone explain where the force that would rotate the wheels is coming from ?

 

[dmw16]

I think that the problem with this 'myth' is a question of the setup. So let's look at a few...

1) Treadmill isn't moving, plane is using its engines to propel itself. Depending on friction the plane could generate enough airspeed to takeoff. So this is plausible

2) The treadmill is moving and induces (via friction) the planes wheels to move. In this case there WILL BE NO airspeed and the plane will not take off. So this is busted

3) The plane is being pulled. See #1.

 

[Linflas]

Originally posted by: smack Down

Originally posted by: Rob9874

Originally posted by: Garth
Do you agree that were the nose of the plane tied to an immovable post in front of the treadmill, the plane would remain stationary while the treadmill moved underneath it?

I do, that's a good analogy. And then, would you agree if someone pulled that post forward, it would not also pull the plane forward, even though the treadmill was matching the speed of its wheels?

The plane can't move forward if the treadmill is matching the speed of the wheels. It is impossible to have movement under such a case.

If the motive force causing a plane to move forward was provided at the wheels your statement would be correct. In this same hypothetical situation an automobile absolutely would not move forward since the motive power is applied to the wheels.

 

[smack Down]

Originally posted by: dmw16
I think that the problem with this 'myth' is a question of the setup. So let's look at a few...

1) Treadmill isn't moving, plane is using its engines to propel itself. Depending on friction the plane could generate enough airspeed to takeoff. So this is plausible

2) The treadmill is moving and induces (via friction) the planes wheels to move. In this case there WILL BE NO airspeed and the plane will not take off. So this is busted

3) The plane is being pulled. See #1.

The force on the plane (2) isn't friction . It is the result of the wheels pushing on the axel.

 

[smack Down]

Originally posted by: Linflas

Originally posted by: smack Down

Originally posted by: Rob9874

Originally posted by: Garth
Do you agree that were the nose of the plane tied to an immovable post in front of the treadmill, the plane would remain stationary while the treadmill moved underneath it?

I do, that's a good analogy. And then, would you agree if someone pulled that post forward, it would not also pull the plane forward, even though the treadmill was matching the speed of its wheels?

The plane can't move forward if the treadmill is matching the speed of the wheels. It is impossible to have movement under such a case.

If the motive force causing a plane to move forward was provided at the wheels your statement would be correct. In this same hypothetical situation an automobile absolutely would not move forward since the motive power is applied to the wheels.

No it is simple math.

Lets say the wheel speed is 4 mph. Then the treadmil also must be 4 mph. The net speed is there for zero.
4 -4 = 0. It has nothing to do with where or how force is applied.

 

[Rob9874]

Originally posted by: smack Down

Originally posted by: Rob9874

Originally posted by: smack Down

Originally posted by: Rob9874

Originally posted by: Garth
Do you agree that were the nose of the plane tied to an immovable post in front of the treadmill, the plane would remain stationary while the treadmill moved underneath it?

I do, that's a good analogy. And then, would you agree if someone pulled that post forward, it would not also pull the plane forward, even though the treadmill was matching the speed of its wheels?

The plane can't move forward if the treadmill is matching the speed of the wheels. It is impossible to have movement under such a case.

How can you say that? If the treadmill is stationary, but someone is pulling to plane by a rope in front of the treadmill, how can the plane not move forward?

Yes it would move forward but you would no longer be matching wheel speed. The only way for an object to be stationary on a treadmill is for the wheel speed to match the treadmill speed. The only way for an object to move forward is the wheel speed is greater then the treadmill speed.

That's right. The problem should be, if a plane was taking off on a treadmill, could the treadmill match the speed of the wheels. And the answer would be no. End of thread.

 

[smack Down]

Originally posted by: Rob9874

Originally posted by: smack Down

Originally posted by: Rob9874

Originally posted by: smack Down

Originally posted by: Rob9874

Originally posted by: Garth
Do you agree that were the nose of the plane tied to an immovable post in front of the treadmill, the plane would remain stationary while the treadmill moved underneath it?

I do, that's a good analogy. And then, would you agree if someone pulled that post forward, it would not also pull the plane forward, even though the treadmill was matching the speed of its wheels?

The plane can't move forward if the treadmill is matching the speed of the wheels. It is impossible to have movement under such a case.

How can you say that? If the treadmill is stationary, but someone is pulling to plane by a rope in front of the treadmill, how can the plane not move forward?

Yes it would move forward but you would no longer be matching wheel speed. The only way for an object to be stationary on a treadmill is for the wheel speed to match the treadmill speed. The only way for an object to move forward is the wheel speed is greater then the treadmill speed.

That's right. The problem should be, if a plane was taking off on a treadmill, could the treadmill match the speed of the wheels. And the answer would be no. End of thread.

Sure it could.

 

[JSFLY]

Originally posted by: Zenmervolt

Originally posted by: smack Down

Originally posted by: Zenmervolt

Originally posted by: smack Down

Originally posted by: Zenmervolt

Originally posted by: smack Down
You can push any object forward on a treadmill at constant speed. If the treadmill is going to match the speed the object moves on it then you can never move the object.

Wrong. There is insufficient friction in the wheels to cause this. As stated, if the treadmill matches the object's forward speed, the wheels simply spin twice as fast for a given groundspeed.

ZV

No as stated the treadmill matches the speed of the object on the treadmill. It does not match the ground speed of the object. Otherwise the car would not have moved.

As long as the wheel are spinning a force is going to be applied to the axel that is porpotional to the speed the wheel is spinning.

Think about it.

If you put a plane on a treadmill and the planes engines are off do you really think it is just going to sit there.

The drag of the landing gear is infinitesimally small. Not enough to consider when compared to the thrust of the engine. If the engine is off, the drag of the landing gear is enough to cause the plane to "ride" the treadmill because there are no other forces acting at the moment. Once the engine is running, it becomes by far the dominant force, easily overcoming the drag of the landing gear. If the engine couldn't overcome the drag of the landing gear, the airplane wouldn't be able to take off even from a normal runway.

ZV

The size of the forces doesn't matter because the treadmill can increase speed infinitly so it can apply an infinite amount of force.

*sigh*

Please don't vote. Or breed.

ZV

No need to insult people.... The problem is counterintuitive by nature.

 

[Rob9874]

Originally posted by: smack Down

Sure it could.

Nope. For something to move forward on a treadmill, the wheels need to move faster than the treadmill. This one is easy.

 

[smack Down]

Why do people think that just because a wheel is free spinning you can't apply a force to it.

Spinning a free spinning wheel is just the reverse of pushing the object and having the wheel spin. If you couldn't move the object by spinning the wheels then you couldn't spin the wheels by moving the object.

 

[randay]

Originally posted by: Zenmervolt

Originally posted by: smack Down

Originally posted by: Zenmervolt

Originally posted by: smack Down

Originally posted by: Zenmervolt

Originally posted by: smack Down
You can push any object forward on a treadmill at constant speed. If the treadmill is going to match the speed the object moves on it then you can never move the object.

Wrong. There is insufficient friction in the wheels to cause this. As stated, if the treadmill matches the object's forward speed, the wheels simply spin twice as fast for a given groundspeed.

ZV

No as stated the treadmill matches the speed of the object on the treadmill. It does not match the ground speed of the object. Otherwise the car would not have moved.

As long as the wheel are spinning a force is going to be applied to the axel that is porpotional to the speed the wheel is spinning.

Think about it.

If you put a plane on a treadmill and the planes engines are off do you really think it is just going to sit there.

The drag of the landing gear is infinitesimally small. Not enough to consider when compared to the thrust of the engine. If the engine is off, the drag of the landing gear is enough to cause the plane to "ride" the treadmill because there are no other forces acting at the moment. Once the engine is running, it becomes by far the dominant force, easily overcoming the drag of the landing gear. If the engine couldn't overcome the drag of the landing gear, the airplane wouldn't be able to take off even from a normal runway.

ZV

The size of the forces doesn't matter because the treadmill can increase speed infinitly so it can apply an infinite amount of force.

*sigh*

Please don't vote. Or breed.

ZV

I told you so.