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#607585 - 13/11/07 11:00 AM Re: Airplane on a treadmill question
Anonymous
Unregistered


I have an impression that some people on this forum have never seen a plane.

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#607586 - 13/11/07 11:01 AM Re: Airplane on a treadmill question
Anonymous
Unregistered


[Sleep]

We should close this thread. We've been chewing this for too long and there's no way to persuade people to change their beliefs.

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#607587 - 13/11/07 11:11 AM Re: Airplane on a treadmill question
Mobycat Offline
Member
*****

Registered: 12/09/00
Posts: 8374
Loc: the hue of dungeons and the sc...
Quote:
Originally posted by vitaly:
Quote:
Originally posted by Mobycat:
[b]
Quote:
Originally posted by MattyX:
[b]Neither matters.
Actually, it does.
...
[/b]
Why is it so hard to comprehend that the only speed that matters is the speed of the plane relative to air? Not to the observer, not to the treadmill, not to the ground, not to your uncle, nothing else, but the AIR.
[Argue] [/b]
Huh?

I'm not arguing that it won't take off. It will. I'm just pointing out that the original problem is worded badly - it never says what the plane is moving in relation to (the ground or the belt).

The "not-take-off" could happen - but ONLY if the speed is relative to the belt - AND it must be zero to do that.
_________________________
"Nature has constituted utility to man the standard and test of virtue. Men living in different countries, under different circumstances, different habits and regimens, may have different utilities; the same act, therefore, may be useful and consequently virtuous in one country which is injurious and vicious in another differently circumstanced" - Thomas Jefferson, moral relativist

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#607588 - 13/11/07 11:12 AM Re: Airplane on a treadmill question
Anonymous
Unregistered


Quote:
Originally posted by RiverPig:
if the speed of the treadmill is the same as the speed that the tires are spinning then the plane will not move if the plane is moving forward then the tires are spinning faster than the treadmill is going
An aircraft's speed is not measured by the rotation of its tires. Ever hear of a pitot tube?

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#607589 - 13/11/07 11:23 AM Re: Airplane on a treadmill question
Anonymous
Unregistered


Quote:
Originally posted by Mobycat:

The "not-take-off" could happen - but ONLY if the speed is relative to the belt - AND it must be zero to do that.
Agreed. Let's nail the plane to the belt and see how that mofo flies. [Smoking]

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#607590 - 13/11/07 11:25 AM Re: Airplane on a treadmill question
Anonymous
Unregistered


Quote:
Originally posted by MattyX:
An aircraft's speed is not measured by the rotation of its tires. ...
For this one it is:

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#607591 - 13/11/07 07:09 PM Re: Airplane on a treadmill question
Anonymous
Unregistered


Quote:
Originally posted by RiverPig:
My official response is that there is not enough information in the question....
All of the necessary information is there. The correct answer has been explained and posted.

Three groups of people will identify themselves:

o Those intelligent enough to understand the correct answer
o Those not intelligent enough to understand the correct answer
o Those who have realized the error of their ways who are too indignant to publicly change their mind

In the event books (how retro!) are too "heavy" for you, one can only ask.....


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#607592 - 14/11/07 03:28 PM Re: Airplane on a treadmill question
Anonymous
Unregistered


Quote:
Originally posted by chumpmann:
Ok, Lets forget all the analogies. Dynos arent a good example, they only move the wheels. A treadmill will move the whole object.

How about the analogy of a plane on a treadmill.

A plane sits on a treadmill, on a calm day, no wind, it is 72 degrees. There is a tree in the ground next to the plane even with the tail.
Now, the treadmill starts to move, the plane starts to move backward on the treadmill. The pilot looks out his window and sees the tree moving from behind him towards him, as the plane is moving backwards on the treadmill. Now the engines start to push the plane to the speed of the treadmill, the tree is now even with the pilot as the engines push the plane, to be even with the tree, on the treadmill. Now as the engines push more the treadmill goes faster, the pilot can look out his window and see the same tree, not moving.
The engines push faster, the treadmill moves faster, the tree is still even with the pilot as he looks out his window. The air around the wings of the plane is as still as the trees next to the plane, the pilot can move his flaps all he wants, he does not have the air resistance to take off.
Just one last thing to add...

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#607593 - 14/11/07 05:57 PM Re: Airplane on a treadmill question
TJ Offline
Member
*****

Registered: 08/03/01
Posts: 7756
Loc: Lawrenceville, NJ, USA
Holy shit

Why is it that some people think the plane would move if the engine thrust pushes it forward on a runway...a "normal scenario...."

But suddenly think it moves like a car, with its tire speed somehow relevant...?

The tires do not push the plane!

The engine THRUST moves the Plane!

If the conveyor MATCHES the speed of the plane...

How would the plane produce a speed to match?

laugh

It has to be pushed forward by its THRUST!

Thrust DOESN'T turn the tires....it moves the plane through the air...and the tires can ONLY turn, IF THE PLANE MOVES....

IF the plane DOES move when the engine thrust pushes it forward......its moving relative to the AIR...

BECAUSE, the thrust DOESN'T rotate the tires, the plane's MOVEMENT does...

As the Movement is ONLY ABLE TO HAPPEN IF THE PLANE IS PUSHED FORWARD,

AND,

It can ONLY be pushed forward relative to the AIR,

What's rolling under the plane ONLY spins its TIRES, and DOESN'T change the plane's movement through the air.

laugh
_________________________
- TJ

2001 Xterra '03 VG33, SE 5 spd, 305/70/16's, Revolvers, UBSkidderz, Doubled AAL's, 3"SL/2"BL, winch/bumpers, skids, sliders, OBA, Snorkel, pine stripes....

Friends don't let friends drive stock.

http://www.gifsoup.com/view/501230/tj-tackling-crawlers-ridge-o.gif

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#607594 - 14/11/07 06:46 PM Re: Airplane on a treadmill question
Anonymous
Unregistered


If the plane sits on the conveyer belt, and the conveyer belt is moving, the plane is moving backwards.
When the engines start to push the plane, it now will stay in one spot, with no possible way to lift itself off the ground.

When the engines push the plane faster(which would be faster than the conveyer belt) it will take off.
It will not take off moving at the same speed as the conveyer belt.

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#607595 - 14/11/07 07:11 PM Re: Airplane on a treadmill question
Anonymous
Unregistered


Quote:
Originally posted by chumpmann:
If the plane sits on the conveyer belt, and the conveyer belt is moving, the plane is moving backwards.
When the engines start to push the plane, it now will stay in one spot, with no possible way to lift itself off the ground.

When the engines push the plane faster(which would be faster than the conveyer belt) it will take off.
It will not take off moving at the same speed as the conveyer belt.


(I'm just gonna' keep on posting it, everytime you say something "smart".)

But just in case you might actually be listening...

A few difinitions for you:

Vp = velocity of plane
Vt = velocity of treadmill

If plane sits on treadmill, and engines turned off, but treadmill starts moving backwards (negative direction):

Vp = Vt, where Vt is some - number

In other words, the plane is moving backwards, at the same velocity as the conveyor.

When plane fires up his engines to prevent backwards movement,

Vp = 0.
Vt = some -#.

Plane isn't moving, now. But it's tires are rotating at an angular velocity necessary to prevent the plane from MOVING backwards with the treadmill. This is not the same as FORWARD movement of the plane. [this is the part you're not grasping]

So when plane starts upping the throttle to actually match the treadmill's velocity, but in the opposite direction,

Vp = some +#
Vt = some -#

And if Vp = some + number, then integral of that velocity (acceleration) will be some + number, too, proving the plane can accelerate, and it will take off.

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#607596 - 14/11/07 07:23 PM Re: Airplane on a treadmill question
Anonymous
Unregistered


I dont care what you think about my solution to the question asked.

I am just stating the obvious instead of over analyzing it.

By the way,I am so glad you want to fuck my theory, but you might have to get in line....

This is why these threads are fun, everyone who "just has to be right all the time", or "has to have the last word" or "just cant take the pressure of being wrong", have to resort to name calling and stupid quotes with gay pictures.....

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#607597 - 14/11/07 07:33 PM Re: Airplane on a treadmill question
Anonymous
Unregistered


Quote:
Originally posted by chumpmann:
I dont care what you think about my solution to the question asked.

I am just stating the obvious instead of over analyzing it.

By the way,I am so glad you want to fuck my theory, but you might have to get in line....

This is why these threads are fun, everyone who "just has to be right all the time", or "has to have the last word" or "just cant take the pressure of being wrong", have to resort to name calling and stupid quotes with gay pictures.....
It has nothing to do with people needing to be right, you just happen to be wrong this time laugh and refuse to look at the question with an open mind and realize you could be wrong in order to find the right answer.

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#607598 - 14/11/07 07:34 PM Re: Airplane on a treadmill question
Anonymous
Unregistered


Quote:
Originally posted by chumpmann:
If the plane sits on the conveyer belt, and the conveyer belt is moving, the plane is moving backwards.
All you're doing here is basically introducing a bit of a tail wind, which the plane's engines will easily overcome.

This will basically "push" on the plane, so when the engines kick in, they'll be that much more effective.

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#607599 - 14/11/07 07:36 PM Re: Airplane on a treadmill question
Rockaholic Offline
Member

Registered: 18/02/02
Posts: 1632
Loc: Reading, MA
Quote:
Originally posted by chumpmann:
If the plane sits on the conveyer belt, and the conveyer belt is moving, the plane is moving backwards.
When the engines start to push the plane, it now will stay in one spot, with no possible way to lift itself off the ground.
This is long, but read it and you'll come to understand why the plane does take off.

we agree that a car (substituted for the airplane for the airplane in the original scenario) on the treadmill will remain staionary to a fixed point on solid ground.

You claim and believe that the plane remains stationary to a fixed point on solid ground when the plane is on the conveyor, much like the car on a treadmill does. However, that assertion is wrong.

The scenario does not say that the plane remains in one spot relative to the ground, only that the conveyor and the airplane have the same speeds in the opposite directions.

The scenario does not say that the plane causes the conveyor to move, but that the conveyor is moved by some other control to match speed of the plane.

So if the plane is taken off of the conveyor and placed onto hard ground and then beings moving towards the conveyor at 10mph, then the conveyor is still going to move at 10mph in the opposite direction of the planes motion...

Now replace the Airplane with a car (make it a Front wheel driven car) and with the same setup as above, but this time the car drives onto the conveyor.
Once the front wheels of this car touch the conveyor the car stops it's forward motion with respect to the ground - with the front wheels on the conveyor spinning at 10 mph on the conveyor and the rear wheels (which were only spinning because the front wheels were moving along the ground and the rear wheels have to follow) are on the ground stationary. We know this is true because the the length of the car and the distance between the wheels remains a constant.

Now replace the Airplane with another car (make it a 2wd Xterra) and with the same setup as above, what happens when the Xterra drives onto the conveyor? When the front wheels contact the conveyor they (being free spinng) double their speed as they continue to move up the conveyor until the rear wheels get onto the conveyor. At that point, all 4 sets of wheels are spinning at 10 mph and the Xterra stays in one spot with respect to the ground. We know this is true because the the length of the Xterra and the distance between the wheels remains a constant.

Now, an Airplane has front wheels and rear wheels, so what happens when the airplane moves onto the conveyor? The front wheels of the plane, which are free spinning, begin to rotate at twice the speed of the rear wheels, which are alos free spinning and on solid ground, and the plane continues to move with respect to the ground...
Does the plane stop when all of the wheel are on the conveyor? No, all of the wheels are free spinning so all of the wheels double their speed, and the plane continues to move with respect to the ground. We know this to be true because the lentgh of the airplane and the distance between the wheels also remains constant, and if the plane remained stationary on the tread mill we would have a problem. We have a problem because the front and rear wheels are all free spinning, they do not provide the forward motion of the plane - they just spin. If your argument is correct that the plane remains staionary with respect to a point on solid ground while on the tread mill and if the front wheels are on the treadmill and the rear wheels are on solid ground, then the front wheels of the plane on the treadmill have a counter motion and so the result can't be greater than zero, so there is no forward motion; yet the rear wheels (on the solid ground) have no counter motion, so those wheels are moving forward...But how can the rear wheels be moving forward if the front wheels are not moving forward when the distance between the wheels remains constant? That is physically impossible!

In fact the front wheels of the plane do not remain stationary in relation to the ground, they move in relation to the ground. That is because the rear wheels are moving in relation to the ground (otherwise planes wouldn't be able to take off of a normal runway) and because the distance between the wheels remains constant the front wheels would have to move forward in relation to the ground on the conveyor to maintain the constant distance. Now (this is important) unlike a car, the front and rear wheels of a plane are all the same in that they are free spinning and do not create the forward motion of the plane, they mearly react to the forward motion of the plane. Since the free spinning front wheels move in relation to the ground on the conveyor this means the rear wheels (being constructed identically) will also move forward in relation to the ground on the conveyor. That means, unlike the wheel driven cars, the conveyor does not cancel out the forward motion of the plane! That means with all the wheels on the conveyor the plane will move forward in relation to the ground, even if the plane starts with all of the wheels on the conveyor.

Since the plane is moving in relation to the ground on the conveyor, then the plane has a groundspeed and a windspeed, and does in fact take off.

The only difference between the plane on a tread mill and the plane on solid ground is that the wheels on the treadmill plane are spinning at twice the rotational speed of the wheels on the solid ground plane.
_________________________
Jeffrey
I'm just trying to put my tires on the rocks of life.

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#607600 - 14/11/07 07:48 PM Re: Airplane on a treadmill question
Anonymous
Unregistered


Quote:
Originally posted by ChefTyler:
It has nothing to do with people needing to be right, you just happen to be wrong this time laugh and refuse to look at the question with an open mind and realize you could be wrong in order to find the right answer.
See what I mean....

why does everyone keep saying that the wheels dont push the plane?
No one has once said that they do.

If the question was asked "can an airplane start on solid ground and move forward onto a treadmill and continue forward?" then you would be explaining it right.

Again, that is not the question.

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#607601 - 14/11/07 08:00 PM Re: Airplane on a treadmill question
Rockaholic Offline
Member

Registered: 18/02/02
Posts: 1632
Loc: Reading, MA
Yes, that is not the question - but it applies because the way the wheels react to the treadmill must remain constant as well.

If you believe the plane remains staionary on the treadmill, then the planes front wheels must also remain staionary on the readmill while the rear wheels (not on the treadmill) do not - as in the front wheel driven car; or that the plane stops moving once the rear wheels are on the treadmill - as in the rear wheel driven car.

In either case, you must now claim that the either the front or rear wheels are no longer free spinning, which they are.

So I ask you this question - what keeps the airplane stationary on the treadmill?
_________________________
Jeffrey
I'm just trying to put my tires on the rocks of life.

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#607602 - 14/11/07 08:08 PM Re: Airplane on a treadmill question
Anonymous
Unregistered


Guys, it really doesn't matter if it's a plane, bicycle, car, truck, whatever.

The vehicle MUST be moving in order for the treadmill to be moving.

Spinning your tires in one place is NOT moving.

So regardless as to what the speedo says your "speed" is, your actual speed may be different when you're on the treadmill.

Frankly, I do burn outs in my new car all the time. Speedo goes up to about 30 mph. Am I really moving at 30 mph? Hell no. I'm standing on the dyam brake pedal at the moment... The tires are spinning at 30 mph EQUIVALENT, but I'm not actually moving.

Once again, the calculated rotational speed of the tires has nothing to do with the actual motion of the vehicle. If the vehicle is not MOVING forward, the treadmill is not moving. If the vehicle is MOVING forward, the treadmill is moving backwards at the same rate. "Moving" is not spinning your tires in one place. Ever. That's NOT velocity!!

It has nothing to do with "getting the last word in" or anything of that sort. This is a very, very simple physics "problem" that is answered very simply. Assuming you understand WTF "moving" means verses standing still spinning your tires.

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#607603 - 14/11/07 08:09 PM Re: Airplane on a treadmill question
Anonymous
Unregistered


Quote:
Originally posted by chumpmann:
Quote:
Originally posted by ChefTyler:
[b]It has nothing to do with people needing to be right, you just happen to be wrong this time laugh and refuse to look at the question with an open mind and realize you could be wrong in order to find the right answer.
See what I mean....

why does everyone keep saying that the wheels dont push the plane?
No one has once said that they do.

If the question was asked "can an airplane start on solid ground and move forward onto a treadmill and continue forward?" then you would be explaining it right.

Again, that is not the question.[/b]
Here's another question, I am trying to formulate it as correctly as possible: "Can people be that retarded or are you just fucking with us?" [Wave]

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#607604 - 14/11/07 08:19 PM Re: Airplane on a treadmill question
Anonymous
Unregistered


It's pretty obvious he's just fucking with us. He's probably a member of the Flat Earth Society.
Just trying to produce a counter argument for every bit of evidence presented, ya know.

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#607605 - 14/11/07 08:33 PM Re: Airplane on a treadmill question
Anonymous
Unregistered


Quote:
Originally posted by 05_X:
It's pretty obvious he's just fucking with us. He's probably a member of the Flat Earth Society.
Just trying to produce a counter argument for every bit of evidence presented, ya know.
What is really scary, is that most of the Flat Earth Society members are for real.
It's time for another Heaven's Gate event.

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#607606 - 14/11/07 08:53 PM Re: Airplane on a treadmill question
Anonymous
Unregistered


Ha - I always thought it was just a debating society to show that any evidence can be debunked with enough mental exercise. Those guys are serious??

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#607607 - 14/11/07 09:35 PM Re: Airplane on a treadmill question
Anonymous
Unregistered


Quote:
Originally posted by 05_X:
Ha - I always thought it was just a debating society to show that any evidence can be debunked with enough mental exercise. Those guys are serious??
Yup...
http://theflatearthsociety.org/forum/index.php?topic=11211.0

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#607608 - 15/11/07 10:18 AM Re: Airplane on a treadmill question
Anonymous
Unregistered


Quote:
Originally posted by chumpmann:
Quote:
Originally posted by ChefTyler:
[b]It has nothing to do with people needing to be right, you just happen to be wrong this time laugh and refuse to look at the question with an open mind and realize you could be wrong in order to find the right answer.
See what I mean....

why does everyone keep saying that the wheels dont push the plane?
No one has once said that they do.

If the question was asked "can an airplane start on solid ground and move forward onto a treadmill and continue forward?" then you would be explaining it right.

Again, that is not the question.[/b]
You can't wrap your head around the actual physics involved and that's ok.

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#607609 - 15/11/07 11:00 AM Re: Airplane on a treadmill question
Anonymous
Unregistered



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