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Plane Problem

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#141
The question has a paradox in it too I think. "The treadmill has a clever design and always matches the speed of the plane" so if the plane is moving at 600 km/h the treadmill would negate it *if* the wheels wouldn't be freewheeling units. Then the plane wouldn't be moving so the treadmill wouldn't be moving and therefore not negating the speed in the first place.

Btw, I still think the plane would take off.
 
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#142
Tak said:
Don't lock it until someone finds out from the original poster of the question gives us a value for friction on the wheels and the length of the treadmill. Once we have that, then it can be worked out as an equation and the real answer can be found :p
Click to expand...

This argument is started to get into the part that I explain in the video. (lizardhands brings in)

I hope me visually yelling at you will help me explain this.

I had to do a pass in Premiere Pro because window movie maker kept ****ing up the file, so its going very slow.
 
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#144
It's this simple. If the wheel bearings generated no friction. Then it would not matter if the tread on the stationary tread mill could move at the speed of light. The plane would still move forward, take off and fly.

However as long as the wheels generate friction, and they are attached to the plane. The tread on the stationary treadmill will always be able to compensate for thrust of the jet by simply moving backwards at the same rate.

Remember the jet, engines, and wheels are all connected, If the jet's engines are always counteracted upon by the equal, but opposite, movement of the tread. It can't move forward.

As long as wheels sit on the tread, and friction exists. (like in the real world) It can't move. So it can't fly.

I'm done. Go about your business.:)
 
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#145
User Name said:
It's this simple. If the wheel bearings generated no friction. Then it would not matter if the tread on the stationary tread mill could move at the speed of light. The plane would still move forward, take off and fly.

However as long as the wheels generate friction, and they are attached to the plane. The tread on the stationary treadmill will always be able to compensate for thrust of the jet by simply moving backwards at the same rate.

Remember the jet, engines, and wheels are all connected, If the jet's engines are always counteracted upon by the equal, but opposite, movement of the tread. It can't move forward.

As long as wheels sit on the tread, and friction exists. (like in the real world) It can't move. So it can't fly.

I'm done. Go about your business.:)
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some serious sudoscience you've got there.

Remember the jet, engines, and wheels are all connected,
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No they are not. The wheels are not connected to the plane in that sense at all, They are freerolling. Rolling forces applied to the wheels have zero effect of the rest of the aircraft.

The reason you can't understand the basic physics behind this is you don't have a grasp of basic physics.
 
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#146
Xendance said:
Btw, I still think the plane would take off.
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And you'd still be wrong.

A plane needs 2 things to fly, an aerofoil (a wing) that creates lift, and forward momentum so the air will pass over the aerofoil to create the left.

This problem simply just removes one of thouse 2 things, we have the forward momentum, but we have no wings! (well they are there, but they are not moving, and therefor not lifting! it'd be the same as if we just cut off the wings and let the plane drive around on the ground).
 
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#148
Moz said:
No they are not. The wheels are not connected to the plane in that sense at all, They are freerolling. Rolling forces applied to the wheels have zero effect of the rest of the aircraft.
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Ever heard of an axle? If the wheels weren't connected to the plane they wouldn't effect it. The wheels are attached to the plane , and generate friction. So they do.

It would only work with zero friction bearings.

OK, now I'm really done.:D

I have to say. I did enjoy the debate though.
 
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#149
Tak said:
Look, guys, the answer is resoundingly NO assuming known values from the real world.


The question is poorly formed, and this isn't the first place it has been debated.

http://forum.physorg.com/index.php?showtopic=10770&st=0
​
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Plane takes off, as it does in the "original problem". Engines apply force in direction d, wheels provide rolling resistance in direction -d. Since airplanes have engines designed to overcome all resisting forces likely to be encountered, plane moves forward, as is expected by conservation of momentum (thrust directed backwards, equal and opposite force forwards.

The conveyor belt is merely an unneeded contrivance to trick the gullible; this is a simple force balances problem with engine forces in one direction and resisting forces in another. Planes are designed to overcome resisting forces (wheels, drag, etc.) so off we go. For those who think otherwise, consider that the plane doesn't "know" it has wheels, it just feels resisting forces on its wheel struts that are further transmitted to the body. The fact those resisting forces are generated by "rolling friction" doesn't change the fact they are still simple adverse forces, like having the brakes on or having an uphill runway. The rolling conveyor is just a method of inducing added rolling friction force, it does not impart any rearward motion to the plane as the vector addition of the engine force and the resisting forces balance in favor of the engine.

Again, the key is that engine forces overwhelm adverse force by orders of magnitude in real aircraft. For those who think the conveyor moves the plane backwards, consider a plane confronting an uphill runway. When brakes are released the plane rolls back slightly then engines take charge and plane moves forward. The "thought experiment" of the conveyor somehow implies, equivalently, that the "uphill" runway dynamically get "steeper" as the plane attempts to make progress against it (implication: increasing adverse force). But airplanes, as we understand them, do not meet increasing adverse forces the engines can't overcome (except for aero drag). That is, rolling resistance is negligible.

To pound the point home further, for those who somehow think the plane is "attached" to the conveyor and is moved backwards diabolically just as the plane tries to move forward: the plane's engines do work W = F ds. For the conveyor to move the plane backwards the conveyor has to do the exact reverse. The only "F" the conveyor has to work with is the rolling resistance and shear inertia. Not enough, as demonstrated by planes taking off from non-conveyor runways. For those who think situation is same as runner on a treadmill: not the same. Runner/treadmill is a "closed system" while airplane engines working against air is an "open sysem".

Note to Atl5p: you can attempt to reformulate this problem all you like, but until you constrain the plane to act in non-normal plane-like ways, you're stuck: the plane flys. Forget the dumb conveyor and just do a little vector algebra to see why.
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:rolleyes:

Yes, the answer is no, idiot.
 
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#151
User Name said:
Ever heard of an axle? If the wheels weren't connected to the plane they wouldn't effect it. The wheels are attached to the plane , and generate friction. So they do.

It would only work with zero friction bearings.

OK, now I'm really done.:D

I have to say. I did enjoy the debate though.
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No, you are just leaving the debate because you are so sure of your stupid moronic ****ing opinion has more baring then fact.

Also my ****ing computer crashed while compiling the video. Piece of ****.
 
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#152
Airplane's speed as measured from the wheels? Or the plane? If the plane is going 10mph and the treadmill is going 10mph, then the plane is actually going 20 mph, so on and so forth. Yes. Ok, i'm had there.


I was reading it as measured from the wheels. If the wheels are going 10mph, and the treadmill is going 10mph....well, that can't happen as reading elsewhere has shown me :). Would never work anyway, friciton on the wheels or not :) So it seems in my reading of the question, I was just flat wrong. The answer isn't 'no' or 'yes', it's impossible.

In reading from the airplane, then the answer is yes and I am wrong, which makes me sad and head hanging in shame and ****.


Oh well, time for porn! :D

(well it was fun, but calling people idiots is just bad show! especially when it's me:p)

EDIT: sorry, didn't mean to break your computer!
​
 
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#153
Tak said:
Airplane's speed as measured from the wheels? Or the plane? If the plane is going 10mph and the treadmill is going 10mph, then the plane is actually going 20 mph, so on and so forth. Yes. Ok, i'm had there.


I was reading it as measured from the wheels. If the wheels are going 10mph, and the treadmill is going 10mph....well, that can't happen as reading elsewhere has shown me :). Would never work anyway, friciton on the wheels or not :) So it seems in my reading of the question, I was just flat wrong. The answer isn't 'no' or 'yes', it's impossible.

In reading from the airplane, then the answer is yes and I am wrong, which makes me sad and head hanging in shame and ****.


Oh well, time for porn! :D

(well it was fun, but calling people idiots is just bad show! especially when it's me:p)

EDIT: sorry, didn't mean to break your computer!
​
Click to expand...
YAY! *tackle hugs Tak*

You've seen the light!
 
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#154
Tak said:
Airplane's speed as measured from the wheels? Or the plane? If the plane is going 10mph and the treadmill is going 10mph, then the plane is actually going 20 mph, so on and so forth. Yes. Ok, i'm had there.


I was reading it as measured from the wheels. If the wheels are going 10mph, and the treadmill is going 10mph....well, that can't happen as reading elsewhere has shown me :). Would never work anyway, friciton on the wheels or not :) So it seems in my reading of the question, I was just flat wrong. The answer isn't 'no' or 'yes', it's impossible.

In reading from the airplane, then the answer is yes and I am wrong, which makes me sad and head hanging in shame and ****.


Oh well, time for porn! :D

(well it was fun, but calling people idiots is just bad show! especially when it's me:p)

EDIT: sorry, didn't mean to break your computer!
​
Click to expand...

Tak you're fine, you disagreed but you acknowledge that you don't know everything.

I don't know everything either, but I do know more on this subject then most. And this question especially pisses me off.

Anyone who knows basic physics says yes.

Anyone doesn't knows basic physics says no.

Most people don't know basic physics.

Majority people say no/

No gets accepted as fact.

This is what I hate about this question.
 
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#155
Moz said:
Tak you're fine, you disagreed but you acknowledge that you don't know everything.

I don't know everything either, but I do know more on this subject then most. And this question especially pisses me off.

Anyone who knows basic physics says yes.

Anyone doesn't knows basic physics says no.

Most people don't know basic physics.

Majority people say no/

No gets accepted as fact.

This is what I hate about this question.
Click to expand...



It's because I get the chics. Everyone agrees with the guy who gets the chicks! :D


It's all good, I actually like being proven wrong or right equally as much. They're both fun. That's why I really enjoy the debates that don't have a right or wrong answer, but such posts usually devolve into flame wars rather than any well thought-out discussion :) Cheers mate!
 
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#156
Tak said:
Airplane's speed as measured from the wheels? Or the plane? If the plane is going 10mph and the treadmill is going 10mph, then the plane is actually going 20 mph, so on and so forth. Yes. Ok, i'm had there.


I was reading it as measured from the wheels. If the wheels are going 10mph, and the treadmill is going 10mph....well, that can't happen as reading elsewhere has shown me :). Would never work anyway, friciton on the wheels or not :) So it seems in my reading of the question, I was just flat wrong. The answer isn't 'no' or 'yes', it's impossible.

In reading from the airplane, then the answer is yes and I am wrong, which makes me sad and head hanging in shame and ****.


Oh well, time for porn! :D

(well it was fun, but calling people idiots is just bad show! especially when it's me:p)

EDIT: sorry, didn't mean to break your computer!
​
Click to expand...

Hold on Tak, your right. Moz, I never attacked you personally. That really was bad form.


If you want to go with this than fine. The plane, and the belt on the tread mill both start out at zero. They are both set on a stationary platform.

As forward momentum of the jet engines is applied. The belt on the tread moves as well. In the opposite direction. As the plane is moving forward on the belt at 10 MPH. The belt is moving exactly 10 MPH in the opposite direction. Niether is actually moving. Since they are on a stable platform. Just like a car, man, or anything else that could go on a tread mill.

The engines are not a seperate force. They are a part of the plane and must move themselves along with the rest of it.

No matter how much thrust is applied though. The plane never moves forward. Because the tread mill, which still has the full weight of the plane on it. Is moving in the exact opposite direction. Again neither are actually going anywhere.

Someone standing on the side would be moving at exactly the same speed, in relation to the planet and the air, as the jet. The wings cannot generate lift because they aren't moving through the air. The planes full weight rests on the wheels. Which still rests on the belt of the treadmill.

Once the plane reaches it's maximum thrust capability. If the whole tread mill's belt is still keeping up with it. It is still going to be moving at zero MPH in relation to the ground, and the air around it. It will still have it's full weight on the belt, and it still will not fly.

If you don't get it now. You won't. So there truly is no reason to continue,

Good night sir. It's been a pleasure.:)
 
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#157
User Name said:
Hold on Tak, your right. Moz, I never attacked you personally. That really was bad form.


If you want to go with this than fine. The plane, and the belt on the tread mill both start out at zero. They are both set on a stationary platform.

As forward momentum of the jet engines is applied. The belt on the tread moves as well. In the opposite direction. As the plane is moving forward on the belt at 10 MPH. The belt is moving exactly 10 MPH in the opposite direction. Niether is actually moving. Since they are on a stable platform. Just like a car, man, or anything else that could go on a tread mill.

The engines are not a seperate force. They are a part of the plane and must move themselves along with the rest of it.

No matter how much thrust is applied though. The plane never moves forward. Because the tread mill, which still has the full weight of the plane on it. Is moving in the exact opposite direction. Again neither are actually going anywhere.

Someone standing on the side would be moving at exactly the same speed, in relation to the planet and the air, as the jet. The wings cannot generate lift because they aren't moving through the air. The planes full weight rests on the wheels. Which still rests on the belt of the treadmill.

Once the plane reaches it's maximum thrust capability. If the whole tread mill's belt is still keeping up with it. It is still going to be moving at zero MPH in relation to the ground, and the air around it. It will still have it's full weight on the belt, and it still will not fly.

If you don't get it now. You won't. So there truly is no reason to continue,

Good night sir. It's been a pleasure.:)
Click to expand...
fail21xf.jpg

1155446336315.jpg

whocares4vn0.jpg


Henceforth I shall only reply with images.
 
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#160
No.

They are not a seperate force.

THEY ARE NOT A FORCE.

THE WHEELS DO NOTHING.

My glider takes 50knots to get off the ground.

In order to get 50knots of speed an need to be pulled by a winch. (this is thrust, NO different from the jet engines) The treadmill will match the speed of the winch pulling. So is the winch cable going to snap or is it going to just pull through the treadmill?

answer that.
 
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