Is it just me or are people fucking thick?

[kalmar]

My 2 cents

The energy of the planes engines is being transfered by a gear (the wheels) to the treadmill, causing the treadmill to move in the opposite direction.

So no movement though the air and no takeoff

I'm really trying hard not to be condescending here so instead I'll just settle for ripping your skull open and cramming a copy of "basic physics for dummies" in there.

[edit] Oh dear, I'm turning into Rev Stu the day he couldn't get his ethernets in a bunch, aren't I?

[piku]

Aaaaaaaaaaah!!!

It'a JET PLANE!!! Not a car!!!

A CAR pushes itself forwards using geared wheels. It pushes against the GROUND.

A PLANE pushes itself off against the AIR, by pushing lots and lots of it through it's engınes!!!

He gets it!

You can regard the wheels as providing a resistant force through the friction in their bearings, directly proportional to their speed in relation to the medium they are on, in this case the moving treadmill. Even if the plane is on the tarmac, moving at 200mph, they will experience some resistance. In this case, the surface is moving backwards at an extra 200mph- so the plane will be going a relative 400mph. Tough on the bearings maybe, but still THE PLANE TAKES OFF!!!!

Oh... no he doesn't.

So close... and yet so far...

[diablo]

but it's all been worked out in the thread if you care to read it.

Like even just read the second post in the thread. kthanks.

Point taken but absolutely no need to be so condescending. Really not an appealing way to point something out.

Sorry, you're right that comment wasn't necessary.

It wasn't but I can see why your patience might be waning.

Have one of these (it neither has wheels, wings or a conveyor beneath it)

[kalmar]

sheepie
*giggle*

[piku]

The plane... sitting on this mystic conveyor... needs to move forwards in order to take off. To do this it has to roll forwards using its wheels (indirectly powered by the engines). Like the original evil post says, this mystic conveyor matches the speed of the wheels exactly.

So the pilot turns on the engines, takes off the brakes on the wheels and... the mystic conveyor starts up and immediately matches the wheel speed exactly down to the macro nano pico metre per quantibillisecond.

Bearings, friction and things like that aren't mentioned, so we can't reason about them. They're beyond the scope of this thought experiement - up there with what the pilot had for lunch and the number of terrorists on board and immigrants in the baggage hold.

Therefore plane no worky...

In the real world, the plane might well fly because of bearing resistance and whatnot. Unfortunately in the real world it would be impossible to make a conveyor this large that worked so obviously this isn't about the real world.

Now I have to go and sit in a quiet room and dribble on myself...

[Roobarb]

Are those audiophile Q-tips up your nose? (avatar)

[ClankClank]

OK then, explain to me how the treadmill exerts a direct, proportional force onto the axle of the FREE SPINNING WHEELS? The backwards force exerted through the wheels is only provided by the small fricitional catching in the bearings, a very small percentage of any force applied. T

You know the trick where you pull a tablecloth out from under some plates? The plates stay there? Because the cloth exerted very little fricitional force on the plates? Like that?

The wheels have nothing to do with it! The treadmill simply makes the wheels spin twice as fast than they would if the plane were on the ground.

Arghh

[Space Cowboy]

Wow! This one's still going! Here's how I resolved this so I could sleep last night (could be nonsense, but worked for me):

You think?

blah ... blah ... helicopter ... blah ... blah ... airplane ... blah ... blah ... nonsense about wheels

I hate to think I am going to be keeping you up tonight, but do you know what the difference between a plane and a helicopter is? Seriously, can you locate the wings on an airplane and the wings on a helicopter. If you can then presumably you'll be able to appreciate the difference between how the wings provide lift on each type of aircraft.

Geez.

Why is this thread still going?

It really is incredibly simple; lift is generated on an airplane by the speed of the air flowing over the wing surface. In the question already posed the treadmill acts as a way of keeping the plane stationary. The jet engines don't provide the lift, they provide thrust to move the plane forward to attain lift. The wheels are there so the plane can go forward until enough lift is generated to get the plane airborne and keep it there. If the plane isn't moving forward there is no fucking lift.

I mean, I knew this basic shit back in middle school. Yet here we are, 18 pages in.

Or it is all a big joke and I've fallen for it.

[kalmar]

The plane... sitting on this mystic conveyor... needs to move forwards in order to take off. To do this it has to roll forwards using its wheels (indirectly powered by the engines).

Nah, the wheels are not indirectly or directly "powered" by the engines. They exert no significant force by themselves. It rolls forward being pushed by the thrust of the engines, which act upon the air, not on the conveyor belt.

Try the real life test: a model plane on an actual treadmill. Your arm is the engine. Push the plane forwards. It goes forwards. There is nothing much stopping it going forwards, is there? Please agree.

So the pilot turns on the engines, takes off the brakes on the wheels and... the mystic conveyor starts up and immediately matches the wheel speed exactly down to the macro nano pico metre per quantibillisecond.

But the plane doesn't care because the wheel speed has nothing to do with the speed of the plane relative to the ground along side the conveyor, the air or the rest of the planet.

Now I have to go and sit in a quiet room and dribble on myself...

Well yes..

[aureole]

I think I could understand what people were saying, if only they were a bit angrier and used more cuss worlds.

[Space Cowboy]

Try the real life test: a model plane on an actual treadmill. Your arm is the engine. Push the plane forwards. It goes forwards. There is nothing much stopping it going forwards, is there? Please agree.

But how can we? It isn't an ordinary treadmill, it is a magic one. We know it is magic because one of the properties described about the treadmill is that it manages to keep the plane from rolling forward.

[kalmar]

In the question already posed the treadmill acts as a way of keeping the plane stationary.

Nope, no it doesn't, that's what's catching a few people out (including the original poster who included the word stationary). The actual question linked to mentions no such condition.

Have a think about it, and you will notice that there's no way for the treadmill (magical or not) to keep the plane stationary, therefore it doesn't, therefore the plane moves, therefore it takes off.

This has now been pointed out every page for the last 5 pages or so, but it will apparently keep being necessary until everyone is dead.

(and if the questioner had actually meant that the plane remains stationary he might as well have specified "a large brick in front of the wheel" which would do the trick just as well, and we wouldn't still be discussing it).

[fred_zen]

Sorry, my sarcasm detector overloaded somewhere around page 16 so I'll just take your post at face value.

The plane... sitting on this mystic conveyor... needs to move forwards in order to take off.

Yes, relatively to the air to be precise.

To do this it has to roll forwards using its wheels

Not necessarily, but no wind was mentioned in the original riddle so we'll assume the air stands (more or less) still relatively to the ground. Yes, the plane (including its wheels) has to move forwards relatively to the ground.

(indirectly powered by the engines).

Huh? The wheels are pushed forward by the plane, which is pushed by its engines so yes, in a sense the wheels are powered by the engines.

Like the original evil post says, this mystic conveyor matches the speed of the wheels exactly.

Which is meaningless unless you define "the speed of the wheels". Fortunately, as we will see the precise speed of the conveyor doesn't really matter.

So the pilot turns on the engines, takes off the brakes on the wheels and... the mystic conveyor starts up and immediately matches the wheel speed exactly down to the macro nano pico metre per quantibillisecond.

Whatever that speed is, but fine.

Bearings, friction and things like that aren't mentioned, so we can't reason about them. They're beyond the scope of this thought experiement - up there with what the pilot had for lunch and the number of terrorists on board and immigrants in the baggage hold.

Fine, they don't really matter. We introduced them because, if there were a lot of friction, the conveyor belt could possibly prevent the plane from taking off. Except, as Kalmar pointed out, that if a plane lost enough energy to friction in its wheel to prevent it from taking off, then horrible things would happen to said wheels. Now, if we are to assume that there is no friction (as you seem to imply), the question is very easy: whatever the belt's speed, it will just make the wheels spin madly, but not slow down the plane at all.

Therefore plane no worky...

Eh?

[Jedburgh]

I think I could understand what people were saying, if only they were a bit angrier and used more cuss worlds.

Shit off, cunt.

BTW I went, "Oh, yeah. Duh." approximately 24 hours ago.

[fred_zen]

I think I could understand what people were saying, if only they were a bit angrier and used more cuss worlds.

Shit off, cunt.

BTW I went, "Oh, yeah. Duh." approximately 24 hours ago.

I used to enjoy this thread quite a lot (physics geekery FTW). Now it needs more pixies.