/sci/ - Science & Math » Thread #14202409

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Anonymous Tue 08 Feb 19:25:11 2022 No.14202409 View Reply Original Report

Quoted By: >>14202518 >>14202579 >>14202623 >>14202629 >>14202661 >>14202674 >>14202771 >>14202820 >>14202870 >>14202877 >>14203326 >>14203627

What is the idea behind this question? Why could it not take off?

Anonymous

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Anonymous Tue 08 Feb 2022 19:29:11 No.14202420 Report

Quoted By:

because the union didn't clear the engineers who designed it to release the Vertical Take Off And Landing (tm) branding to the intermediary who would then requisition a lease from the underwriter who would apply for a special trade exemption from the EU who would then ask the US DOT for decals indicating that the aircraft was a VERTICAL TAKE-OFF AND LANDING CRAFT and therefore would require special clearance from OSHA for the proliferation of nondescript indicators of ALL HAIL HYPNOTOA-

Anonymous

Anonymous Tue 08 Feb 2022 19:29:37 No.14202423 Report

Quoted By: >>14202449 >>14202462 >>14202507

>what is the idea behind the questio
To confuse midwits
>Why could it not take off
It can, the plane is propelled by the jet engines, not by the wheels. The wheels will spin twice as fast as a regular takeoff, but the airspeed will be the same.

Anonymous

Anonymous Tue 08 Feb 2022 19:36:50 No.14202449 Report

Quoted By: >>14202457 >>14202803

>>14202423
>twice
How did you figure that out? I’m stuck trying to understand the rotation speed lf the wheels

Anonymous

Anonymous Tue 08 Feb 2022 19:38:41 No.14202457 Report

Quoted By: >>14202803

>>14202449
the rotation speed of the wheels literally doesn't matter, they're just a bearing between the aircraft and the ground, all the forward thrust comes from the jet engines pushing against the atmosphere

Anonymous

Anonymous Tue 08 Feb 2022 19:40:39 No.14202462 Report

Quoted By: >>14202507 >>14202619 >>14202803

>>14202423
As long as the wheels are in contact with the ground, the kinetic energy from the jet engines increases the torque of the wheels making the conveyor belt move even faster in the opposite direction. It can't take off because it can't gain any forward thrust as long as it is in contact with the ground

Anonymous

Anonymous Tue 08 Feb 2022 19:43:03 No.14202476 Report

Quoted By: >>14202543

I think the wheels would rotate faster and faster until they explode but the plane wouldn’t move

Anonymous

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Anonymous Tue 08 Feb 2022 19:48:37 No.14202507 Report

Quoted By: >>14202556 >>14202803

>>14202423
>>14202462

this question is a trap for midwits because it's always improperly stated and people make assumptions. IF (somehow) not matter how much the thrust from the engines increases, the wheels rotate faster and faster but the plane itself makes no forward movement, it will not takeoff, because lift is generated by relative wind over the wings. IN PRACTICE, this is not what happens because the plane will still be accelerated down a 'moving' runway, despite the fact that the 'ground' is moving in the opposite direction.

Now we don't have to have this thread anymore.

Anonymous

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Anonymous Tue 08 Feb 2022 19:50:23 No.14202518 Report

Quoted By:

>>14202409
>the conveyor belt is going backwards
>pilot hits the brakes
>plane lurches forward and launches up

Anonymous

Anonymous Tue 08 Feb 2022 19:54:17 No.14202543 Report

Quoted By:

>>14202476
OP here. I'm not even sure I understand the question but I think it means that if the plane was on a regular runway and the wheels were rolling at "x rpm", then on the conveyor belt scenario the conveyor belt is moving as fast as to make the wheels roll that fast if the plane was stationary. So to put it simply, the wheels are rolling twice as fast in the conveyor belt experiment.

Anonymous

Anonymous Tue 08 Feb 2022 19:57:09 No.14202556 Report

Quoted By: >>14202609 >>14202615

>>14202507
>IN PRACTICE, this is not what happens because the plane will still be accelerated down a 'moving' runway, despite the fact that the 'ground' is moving in the opposite direction.
How does this translate to an increased amount of wind moving over the wings despite the plane remaining in the same position

Anonymous

Anonymous Tue 08 Feb 2022 20:02:09 No.14202579 Report

Quoted By: >>14202609

>>14202409
You get no lift because you are still relative to the air around you.

Anonymous

Anonymous Tue 08 Feb 2022 20:08:10 No.14202609 Report

Quoted By: >>14202616 >>14202618 >>14202632

>>14202556
>>14202579
>despite the plane remaining in the same position
It doesn't remain in the same position. It's pushed forward by the engines. I don't understand how this confuses people. Do you think planes are propelled by their wheels?

Anonymous

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Anonymous Tue 08 Feb 2022 20:09:48 No.14202615 Report

Quoted By:

>>14202556

It doesn't - in a 'practical' scenario the plane won't be stationary but will accelerate down the runway. The engines just have to work slightly harder to compensate for the fact that the runway is moving in the opposite direction. Kind of like you have to run harder to get to the top of the down escalator.

Anonymous

Anonymous Tue 08 Feb 2022 20:09:59 No.14202616 Report

Quoted By: >>14202630

>>14202609
True but at the same time, if the plane moves forward, it means the conveyor belt doesn’t go as fast as the wheels in the opposite direction, which contradicts the initial problem.

Anonymous

Anonymous Tue 08 Feb 2022 20:10:34 No.14202618 Report

Quoted By: >>14202630 >>14202642

>>14202609
But as the engine tries to push it forward the conveyer belt speeds up to cancel out the distance it would accumulate.

Anonymous

Anonymous Tue 08 Feb 2022 20:10:35 No.14202619 Report

Quoted By:

>>14202462
>the torque of the wheels
The wheels are free spinning. There is no torque.
>it can't gain any forward thrust
A 747 has four jet engines producing 40,000 pounds of thrust each at a standstill. It can and will move, regardless of what the wheels are doing.

Anonymous

Anonymous Tue 08 Feb 2022 20:10:55 No.14202623 Report

Quoted By:

>>14202409
People assume that the wheels of a plane are driven like those of a car and it uses them to get up speed for take off. This, of course, is not the case.

Anonymous

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Anonymous Tue 08 Feb 2022 20:12:06 No.14202629 Report

Quoted By: >>14202744

>>14202409
No air under the wings

Anonymous

Anonymous Tue 08 Feb 2022 20:12:08 No.14202630 Report

Quoted By: >>14202638 >>14202639 >>14202644

>>14202618
>>14202616
Why is the concept of a free spinning wheel literally impossible for you midwits?

Here's a plane, on a conveyer belt, taking off. I don't know what more you want.
https://youtu.be/YORCk1BN7QY

Anonymous

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Anonymous Tue 08 Feb 2022 20:12:14 No.14202631 Report

Quoted By: >>14202650

What if the conveyor belt had no internal drive? The plane would move and take off because there was no transfer of momentum between the wheel and rollers. But a car couldnt move forward, correct?

Anonymous

Anonymous Tue 08 Feb 2022 20:12:17 No.14202632 Report

Quoted By: >>14202644

>>14202609
Lift is generated by the disparity in air pressure/speed above and below the wing.

The engines can indeed push it forward on the treadmill, but the air above the treadmill is still relatively static. Jet engines don't push/pull any air across the wing directly, they push the plane through the air in order to generate that disparity.

Anonymous

Anonymous Tue 08 Feb 2022 20:12:39 No.14202634 Report

Quoted By:

So essentially the plane is zero friction ice? Guess it will glide forward?

Anonymous

Anonymous Tue 08 Feb 2022 20:13:39 No.14202638 Report

Quoted By:

>>14202630
Does the conveyer belt accelerate here?

Anonymous

Anonymous Tue 08 Feb 2022 20:13:41 No.14202639 Report

Quoted By:

>>14202630
Alright I get it

Anonymous

Anonymous Tue 08 Feb 2022 20:14:05 No.14202642 Report

Quoted By: >>14202666

>>14202618
The is no real mechanical connection between the runaway and the engines. The wheels just spin passively, the runaway can't transfer any meaningful force to the engines through them.

Anonymous

Anonymous Tue 08 Feb 2022 20:14:19 No.14202644 Report

Quoted By: >>14202652 >>14203017

>>14202632
see
>>14202630
the engines push against the atmosphere and generate motion relative to the atmosphere regardless of what the runway is or isn't doing. The plane is not magically held in place by it's wheels.

Anonymous

Anonymous Tue 08 Feb 2022 20:15:30 No.14202649 Report

Quoted By:

same reason a plane in the sky can accelerate?

Anonymous

Anonymous Tue 08 Feb 2022 20:15:34 No.14202650 Report

Quoted By:

>>14202631
Cars are driven by their wheels. Planes are not driven by their wheels. So you're correct.

Anonymous

Anonymous Tue 08 Feb 2022 20:16:00 No.14202652 Report

Quoted By: >>14202658

>>14202644
>generate motion relative to the atmosphere
they dont

Anonymous

Anonymous Tue 08 Feb 2022 20:18:03 No.14202658 Report

Quoted By: >>14202672

>>14202652
>jet engines don't generate motion relative to the atmosphere
you better tell all those planes in the sky that their engines aren't real

Anonymous

Anonymous Tue 08 Feb 2022 20:18:29 No.14202661 Report

Quoted By: >>14202673 >>14202768

>>14202409
Brainlets think the thrust comes from the wheels.

Anonymous

Anonymous Tue 08 Feb 2022 20:18:56 No.14202666 Report

Quoted By:

>>14202642
Doesn't the friction make it like tiny gears that interlock them making it like a exercise bike?

Anonymous

Anonymous Tue 08 Feb 2022 20:20:18 No.14202672 Report

Quoted By: >>14202678

>>14202658
if you're sitting still on the conveyor belt, the engine is not generating motion relative to the atmosphere

Anonymous

Anonymous Tue 08 Feb 2022 20:20:21 No.14202673 Report

Quoted By:

>>14202661
imagine all that force on those tiny wheels. they would explode

Anonymous

Anonymous Tue 08 Feb 2022 20:20:26 No.14202674 Report

Quoted By:

>>14202409
>t. what is wing

Anonymous

Anonymous Tue 08 Feb 2022 20:21:56 No.14202678 Report

Quoted By: >>14202685 >>14202689 >>14202716

>>14202672
>if you're sitting still on the conveyor belt
You aren't sitting still on the conveyer belt. The engines are pushing you forward with a combined 16,000 pounds of thrust. The wheels are free spinning and isolate the plane mechanically from the ground. Airspeed is all that matters.

Anonymous

Anonymous Tue 08 Feb 2022 20:23:01 No.14202685 Report

Quoted By: >>14202689

>>14202678
Sorry, 160,000 pounds thrust. 4x40,000.

Anonymous

Anonymous Tue 08 Feb 2022 20:24:05 No.14202689 Report

Quoted By: >>14202696

>>14202685
>>14202678
Why don't the wings just come off then?

Anonymous

Anonymous Tue 08 Feb 2022 20:25:03 No.14202696 Report

Quoted By: >>14202723 >>14202726 >>14202803

>>14202689
Which do you think requires more force?
>spinning a wheel that's intended to spin freely
>ripping the fucking main wing spar out of a Jumbo jet

Anonymous

Anonymous Tue 08 Feb 2022 20:29:29 No.14202716 Report

Quoted By: >>14202723

>>14202678
Are we getting into a semantic discussion of what the function of the conveyor belt is in the experiment?

It seems like the intent is, as a treadmill, to control the speed of the plane relative to the motion of the belt such that it doesn't move relative to ground around it or the viewer, in effect asking "if the plane doesnt move forward, can it take off?"

It could theoretically if the windspeed was large, but the experiment makes no allowance of that.

The plane generates lift by moving through the air, if the conveyor belt prevents that movement then it doesnt generate lift.

Or are you saying it's intentionally misleading or a trick question, and the conveyor is totally irrelevant?

Anonymous

Anonymous Tue 08 Feb 2022 20:31:01 No.14202722 Report

Quoted By: >>14202793

>friction
>spinning wheels
What seems obvious to me, but no one ever brings up is how this is a variable
Imagine:
A. Wheel bearings have 0 friction. No force from treadmill transferred to plane
B. Wheels welded on. Treadmill transfers force to plane
I think this is primarily what it depends on, and goes unsaid and undefined... and that lack of definition is what leads to half the arguments

Anonymous

Anonymous Tue 08 Feb 2022 20:31:05 No.14202723 Report

Quoted By: >>14202735 >>14202803

>>14202696
But that's the thing. If the plane outpaces the conveyor belt, it means that the speed of the belt no longer matches the speed of the wheels, which violates the initial condition.
The only way to get around this, is that the wheels are skidding.
>>14202716
Of course it's misleading, that's why it generates so much discussion.

Anonymous

Anonymous Tue 08 Feb 2022 20:31:51 No.14202726 Report

Quoted By:

>>14202696
> A massive conveyer belt the size of an entire runway that can accelerate to massive speeds vs a few nuts and bolts.
anon...

Anonymous

Anonymous Tue 08 Feb 2022 20:34:56 No.14202735 Report

Quoted By: >>14202753 >>14202803

>>14202723
"The thing" is that you physically cannot build a conveyer belt capable of infinite speed, which renders the initial condition moot. Any normal conveyer belt will work as discussed – slightly increasing takeoff friction, but not noticeably.

Anonymous

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Anonymous Tue 08 Feb 2022 20:37:45 No.14202744 Report

Quoted By:

>>14202629
oh my

Anonymous

Anonymous Tue 08 Feb 2022 20:40:18 No.14202753 Report

Quoted By: >>14202763

>>14202735
>but you can't build a conveyor belt like that!
There's a similar catch in pretty much every other thought experiment, and this one never specifies that the conveyor belt is supposed to be 'normal', whatever you think that means.

Anonymous

Anonymous Tue 08 Feb 2022 20:42:37 No.14202763 Report

Quoted By: >>14202782

>>14202753
The literal wording in the OP is very much feasible and a plane would take off under those conditions, at most you might have to replace the bearings on the wheels to ensure they can take double the take off speed.

Anonymous

Anonymous Tue 08 Feb 2022 20:43:36 No.14202768 Report

Quoted By:

>>14202661
Must be pretty strong wheels if they can launch the plane thousands of kilometers away

Anonymous

Anonymous Tue 08 Feb 2022 20:44:40 No.14202771 Report

Quoted By:

>>14202409
It will if you add a giant fan in the front.

Anonymous

Anonymous Tue 08 Feb 2022 20:47:56 No.14202782 Report

Quoted By: >>14202797

>>14202763
The OP does NOT say that the belt spins at 'normal' takeoff speed, it says that the belt speed matches the wheel speed.
If the wheels outpace the belt, the belt speed no longer matches the speed of the wheels.
If the wheels are spinning at twice the takeoff speed, the belt is also spinning at twice the takeoff speed.

Anonymous

Anonymous Tue 08 Feb 2022 20:50:22 No.14202793 Report

Quoted By:

>>14202722
Exactly.
0 friction-> the plane takes off while wheels spin extremely fast
Friction-> the plane doesn’t move an inch since all movement forward is offset by acceleration of the belt which increaseth friction

It gets more complicated if we take into account that wheels break down. Now in both cases wheels explode

Anonymous

Anonymous Tue 08 Feb 2022 20:51:48 No.14202797 Report

Quoted By: >>14202846 >>14202876

>>14202782
It says speed of the wheels not the speed of the wheels rotation, which is maximized at takeoff speed, which means the rotation rate of the wheels is at maximum twice that off the takeoff speed.

It doesn't even matter, no matter what assumptions you make the plane will take off, if you assume a frictionless belt with infinite power going at light speed then the plane will still take off because the frictionless bearings transfer no power to the plane.

Anonymous

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Anonymous Tue 08 Feb 2022 20:54:44 No.14202803 Report

Quoted By: >>14202819 >>14202876 >>14202878 >>14202906

>>14202449
>>14202457
>>14202462
>>14202507
>>14202696
>>14202723
>>14202735
>>14202735
>>14202735
question for every anon here
what speed is the conveyor going? Bonus question: what speed are the wheels moving?

bottom text

Anonymous

Anonymous Tue 08 Feb 2022 20:57:07 No.14202819 Report

Quoted By:

>>14202803
It is going at infinite speed, unironically. Do the test with your hands, one rolling against the other rolling in the opposite direction

Anonymous

Anonymous Tue 08 Feb 2022 20:57:39 No.14202820 Report

Quoted By:

You guys get filtered because you don't consider the properties of the conveyor belt.
>>14202409
The friction of the wheels would ofcourse be tiny as they are free moving but because the conveyor belt allways matches the speed of the wheel, so tries to keep it place, it would end up approaching infinite speed, which results in infinite friction, keeping the plane in place.

Anonymous

Anonymous Tue 08 Feb 2022 21:02:47 No.14202846 Report

Quoted By:

>>14202797
The friction is not zero on the wheels. It's tiny but it exist, logically the wheels or the conveyor belt would just break.

Anonymous

Anonymous Tue 08 Feb 2022 21:06:48 No.14202870 Report

Quoted By: >>14202878 >>14202896

>>14202409
>ITT, a bunch of retards who have no idea why planes fly
are you all working for Boeing or what the fuck is going on?
hint: there is a reason why the wings have a certain shape

Anonymous

Anonymous Tue 08 Feb 2022 21:08:32 No.14202876 Report

Quoted By:

>>14202797
>It says speed of the wheels not the speed of the wheels rotation
It also says speed of the conveyor belt and not the speed of the belts surface, but 'speed of the wheels' means wheel radius times wheel rotation rate, and 'speed of the conveyor belt' means the speed of the surface of the belt. The belt itself is not moving, and neither are the wheels. Or the wheels are sliding on the belt without rotating.
>It doesn't even matter, no matter what assumptions you make the plane will take off
It's not an assumption that the belt speed matches the speed of the wheels, that's literally a part of the question.
>>14202803
The wheels are skidding.

Anonymous

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Anonymous Tue 08 Feb 2022 21:08:47 No.14202877 Report

Quoted By: >>14202950 >>14202982

>>14202409

Anonymous

Anonymous Tue 08 Feb 2022 21:09:03 No.14202878 Report

Quoted By:

>>14202870
answer the question >>14202803
>>14202803
>>14202803

Anonymous

Anonymous Tue 08 Feb 2022 21:13:16 No.14202896 Report

Quoted By:

>>14202870
t. retard who can't read

The only way the conveyor bent can match the speed of the wheels is if the plane is prevented from accelerating.

Anonymous

Anonymous Tue 08 Feb 2022 21:15:33 No.14202906 Report

Quoted By:

>>14202803
Mathematically speaking, it would at first try to be 1 m/s but because the tiny amount of friction would barely decrease the speed of the plane so it adjust instantly to 1 m/s of the speed it already accelerate the wheel to + 0,99... m/s speed the wheel still moves forward. And so on, it will approach infinite speed until the wheels explode from the heat the near infinite friction causes.

Anonymous

Anonymous Tue 08 Feb 2022 21:27:34 No.14202950 Report

Quoted By: >>14202962

>>14202877
If the plane accelerates, the wheels would accelerate twice as compared to a regular plane on regular runway because the belt is going twice as fast in the opposite direction.

What exactly is the issue here?

Anonymous

Anonymous Tue 08 Feb 2022 21:30:19 No.14202962 Report

Quoted By:

>>14202950
>le twofold speed
Is this some kind of joke? Try to visualize your proposition.

Anonymous

Anonymous Tue 08 Feb 2022 21:35:28 No.14202982 Report

Quoted By: >>14202990

>>14202877
If the speed of the wheels is zero, the speed of the conveyor belt to the opposite direction is also such that the speed of the wheels is zero. Theoretically the plane could take off if the conveyor belt moves in such a way that it keeps the wheels stationary while the plane itself is moving

Anonymous

Anonymous Tue 08 Feb 2022 21:37:09 No.14202990 Report

Quoted By: >>14203027

>>14202982
>Theoretically the plane could take off if the conveyor belt moves in such a way that it keeps the wheels stationary while the plane itself is moving
How would it do that?

Anonymous

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Anonymous Tue 08 Feb 2022 21:43:33 No.14203017 Report

Quoted By:

>>14202644
Checked.

The conveyor puts so much torque on the wheels that the trivial amount of friction in their bearings is transferred to the fuselage and is able to overcome the enormous force of the engines' trust. Unintuitively, the wheels are actually spinning backwards in this scenario. Nevermind the fact that the magnitude of velocity involved in the wheels/conveyor would be impossible to achieve, physically, because it is obvious that all materials known to man would almost instantly heat to the point that the wheels/conveyor melt away. Even granting impossibly indestructible materials, I'm not sure whether the amount of torque required could be generated (assuming typical bearing friction) without the wheels rotating faster than the speed of light at their perimeter.

Anonymous

Anonymous Tue 08 Feb 2022 21:46:38 No.14203027 Report

Quoted By: >>14203074 >>14203182

>>14202990
I mean, is the "speed" here is referring to RPM (rotations per minute). The plane itself could be moving on the conveyor belt while RPM of the wheels were zero if the belt was moving at the same speed as the plane. But if you mean that the speed is the linear speed of the wheels, then I think the plane could still accelerate because then the belt would just accelerate that much to the opposite direction and the wheels would just spin a bit faster than normal and there would be no problem.

Anonymous

Anonymous Tue 08 Feb 2022 22:00:51 No.14203074 Report

Quoted By: >>14203185

>>14203027
The conveyor is moving so rapidly as to cause the wheels to spin so fast that the bearing friction is able to cancel out the plane's forward motion.

Anonymous

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Anonymous Tue 08 Feb 2022 22:01:16 No.14203076 Report

Quoted By: >>14203372

Anonymous

Anonymous Tue 08 Feb 2022 22:23:15 No.14203182 Report

Quoted By:

>>14203027
>I mean, is the "speed" here is referring to RPM (rotations per minute).
Clearly it means the wheels are not moving forward on the conveyor.

Anonymous

Anonymous Tue 08 Feb 2022 22:23:29 No.14203185 Report

Quoted By:

>>14203074
The plane can take off if the wheels don't spin

Anonymous

Anonymous Tue 08 Feb 2022 23:01:30 No.14203326 Report

Quoted By:

>>14202409
The weight of the plane creates friction between the wheels and the ground, the conveyor has a certain amount of grip on the whole plane.

The engines would need to create more forward force than the backwards force to which the conveyor contributes to.

Anonymous

Anonymous Tue 08 Feb 2022 23:12:23 No.14203372 Report

Quoted By:

>>14203076
This is a non sequitur, it says the treadmill will fail to track the plane and the plane will take off. But the point is that if the treadmill doesn't fail to track the plane then it will not take off.

Anonymous

Anonymous Wed 09 Feb 2022 00:08:17 No.14203603 Report

Quoted By:

airplanes don't take of because of wheels or engines, they take of because of their wings.
as soon as there is enough air moving across the wing it will be lifted upwards.

Anonymous

Anonymous Wed 09 Feb 2022 00:14:30 No.14203627 Report

Quoted By:

>>14202409
Don't know how planes take off but I imagine it has something to do with momentum. The friction probably prevents the proper build up.

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