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Plane Problem

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#401
The wheels and the treadmill always spin at the same rate. They only effect each other.

The planes body is moving in relation to the Earth, the plane moves forward --->.

The wheels just spin faster than normal. The wheels are only on the plane to keep it off the ground, and eliminate friction. You are left with some rolling resistance, but not enough to stop the massive amount of thrust from the engines.

The engines thrust the plane forward through the air overcoming drag, at this point the plane is moving forward in relation to the Earth, and the wings generate lift. = takeoff.
 
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#404
BuddyLee said:
The wheels and the treadmill always spin at the same rate. They only effect each other.

The planes body is moving in relation to the Earth, the plane moves forward --->.

The wheels just spin faster than normal. The wheels are only on the plane to keep it off the ground, and eliminate friction. You are left with some rolling resistance, but not enough to stop the massive amount of thrust from the engines.

The engines thrust the plane forward through the air overcoming drag, at this point the plane is moving forward in relation to the Earth, and the wings generate lift. = takeoff.
Click to expand...

When the plane is moving relative to the earth, it is also moving through the air, which then puts airflow over the wings = take off.

I asked my physics teacher who used to be an aircraft engineer and even he said it'd take off.
 
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#405
To those that were finally convinced by the torturous explanations that physics requires of the uninitiated, welcome to the side of rationality. ;)

For the others, will you next argue that rockets can't work without an atmosphere, because there's nothing for them to push against? I'd like to see you prove that one too ;)

Huzzah for heavier than air flying machines!

Edit: to clarify, the plane will fly
 
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#411
I posted this on another forum. One guy, a US Marine, asked some high ranking official in the marines that is the head of the aeronautical department or something like that (I can't remember, he deleted the post after he realized he was wrong) and the high ranking 3-star Lieutenant General said that the plane can't take off.

Also, an "aircraft engineer for GE, yeah, a-10, he helped design that engine" said that it can't take off....

I've lost a little confidence in the aeronautical divisions of the Marines and GE now...:p
 
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#414
In this kind of physics problem, you have to assume that the bearings/wheels are frictionless. Since they are, there is no friction being applied to the wheels and the plane will be able to take off. The only catch is that both the wheels and the conveyer will almost instantly speed up to infinity and blow the whole universe apart, but rest assured, the plane will move and take off.

Now back to a little more reality, the wheels and bearings have friction. Friction pushes the plane in the opposite direction, hence why when you let off the gas in a [manual transmission] automobile, the car will eventually come to a stop without the need to touch the brake (in an automatic transmission vehicle, it will automatically downshift, which uses the vaccuum of the motor to slow the car down). The faster the wheels turn, the more friction is created, so the engines of the plane will always be combating this energy so long as it's attempting to move forward, or in any direction for that matter. The conveyer will still have to accelerate to very high speeds, but the plane won't be able to take off, because even though the jet engines move air in order to propel the plane forward (they aren't direct drive like an automobile), there is still friction being placed on the wheels/bearings that is holding the plane back, and this energy, in turn, is transferred to the body of the aircraft.

Both answers are correct. It's just how you look at the problem. In beginners physics (is there such a thing? lol), you have to make a few assumptions, and one of them is to assume that any kind of bearing you're dealing with is frictionless.
 
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#416
enugh friction to stop a plane...

a 747 produces 206,8 kN with its tiny engines. edit: what i forgot was: with any speed the plane gains, it has lesser weight on the weels.

http://en.wikipedia.org/wiki/Rolling_friction said:
In usual cases, the normal force on each tire will be the mass of the object (wheels plus what they're supporting) times the gravitational acceleration (9.81 m
Click to expand...
 
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#417
This thread has earned my certificate of recognition:

smartchart.jpg
 
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#420
BuddyLee said:
The wheels and the treadmill always spin at the same rate. They only effect each other.

The planes body is moving in relation to the Earth, the plane moves forward --->.

The wheels just spin faster than normal. The wheels are only on the plane to keep it off the ground, and eliminate friction. You are left with some rolling resistance, but not enough to stop the massive amount of thrust from the engines.

The engines thrust the plane forward through the air overcoming drag, at this point the plane is moving forward in relation to the Earth, and the wings generate lift. = takeoff.
Click to expand...

Check the original site that the problem was posted on. It doesn't say anywhere that the treadmill matches the speed of the wheels, it says it matches the speed of the aircraft as a whole.

Also check the site because the official answer to the problem has been posted, so that this "riddle" can finally be over. :)
 
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