| DeathBy240 |
A plane (747 passenger jet) is sitting on a runway that can move (some sort of band conveyor). The plane moves in one direction, while the conveyor moves in the opposite direction. This conveyor has a control system that tracks the planes speed and tunes the speed of the conveyor to be exactly the same (but in the opposite direction).
The question is:
Will the plane (747 passenger jet) take off or not? |
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| bigmack000 |
quote:
Originally posted by DeathBy240
A plane (747 passenger jet) is sitting on a runway that can move (some sort of band conveyor). The plane moves in one direction, while the conveyor moves in the opposite direction. This conveyor has a control system that tracks the planes speed and tunes the speed of the conveyor to be exactly the same (but in the opposite direction).
The question is:
Will the plane (747 passenger jet) take off or not?
the thrust of the jet engines is so intense it would just over power the conveyor. |
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| ehos |
No. The airspeed over the wings won't produce enough lift to produce flight.
(Unless there is an equivilant amount of air moving on this magical belt, then yes). |
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| ChromeDragon |
| Bingo, bango, bongo. |
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| Bad Egg |
| It depends if Michael Moore is sitting near the snack cart or not. |
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| snugs |
| Is it an african 747 or a european 747? :dunno: |
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| oldraven |
It'll take off. The plane is moving, not just its wheels. Now the wheels are moving at twice the speed of the plane, but it'll still take off.
BTW, these must be some very stupid engineers. Then again, it's pretty common for Engineers to waste vast amounts of time and money to play with experiments rather than actual improve anything. :p
(you know it's true, Snugs) |
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| snugs |
quote:
Originally posted by oldraven
BTW, these must be some very stupid engineers. Then again, it's pretty common for Engineers to waste vast amounts of time and money to play with experiments rather than actual improve anything. :p
(you know it's true, Snugs)
I'll get back to you on that, I'm building a replica of this scenario out of spaghetti and toothpicks.... might have definitive results in 8 to 10 weeks. :D |
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| SilverZ24 |
| I can't see how it would take off because if it suddenly did come off the ground it would basically be standing still with the engines on full. So my vote is no. |
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| oldraven |
quote:
Originally posted by SilverZ24
I can't see how it would take off because if it suddenly did come off the ground it would basically be standing still with the engines on full. So my vote is no.
The plane moves in one direction, while the conveyor moves in the opposite direction.
This sentence is all you need to know. |
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| bigmack000 |
quote:
Originally posted by SilverZ24
I can't see how it would take off because if it suddenly did come off the ground it would basically be standing still with the engines on full. So my vote is no.
pretty much the belt will only match the speed of the tires not the jet. so really the tires will either not move and get burnt off or they will just get pushed to move no mater what .
if this was car it wouldn't go any where caue its powered at the wheels airplanes are not It will fly |
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| SilverZ24 |
quote:
Originally posted by oldraven
The plane moves in one direction, while the conveyor moves in the opposite direction.
This sentence is all you need to know.
But isn't the plane on the conveyor and therefore relative to everything else around it not moving? Just like being on a treadmill?
Lets say you can run on the ground and jump 6 feet. Now if you run full speed on a treadmill and try to jump are you going to go 6 feet? I don't think so.
Maybe I'm still thinking about it wrong (hey I'm an accountant lol) but that is how I see it. :dunno:
*edit* I didn't see bigmacks post, but that still doesn't change how I see it. lol |
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| snugs |
quote:
Originally posted by oldraven
The plane moves in one direction, while the conveyor moves in the opposite direction.
This sentence is all you need to know.
Think "treadmill"..... I've moved on to sticky notes and paperclips, will still be 8-10 weeks before results are available though. |
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| bigmack000 |
quote:
Originally posted by SilverZ24
But isn't the plane on the conveyor and therefore relative to everything else around it not moving? Just like being on a treadmill?
Lets say you can run on the ground and jump 6 feet. Now if you run full speed on a treadmill and try to jump are you going to go 6 feet? I don't think so.
Maybe I'm still thinking about it wrong (hey I'm an accountant lol) but that is how I see it. :dunno:
*edit* I didn't see bigmacks post, but that still doesn't change how I see it. lol
lol :p
snugs i think chop sticks and post its will work better |
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| HeavyEarly87T |
quote:
Originally posted by snugs
I'll get back to you on that, I'm building a replica of this scenario out of spaghetti and toothpicks.... might have definitive results in 8 to 10 weeks. :D
Somebody got a government grant? LOL
It is election time. |
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| snugs |
quote:
Originally posted by snugs
Think "treadmill"..... I've moved on to sticky notes and paperclips, will still be 8-10 weeks before results are available though.
No, scratch that.... the sticky notes aren't doing the trick.... :( |
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| snugs |
quote:
Originally posted by HeavyEarly87T
Somebody got a government grant? LOL
It is election time.
NSERC baby! :p |
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| snugs |
| lol, actually I know the answer to this, but I'm waiting for my funding to come through before I share it with anybody.... :p |
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| JustinL |
My first reaction was to vote no. But I want to change my answer to yes.
I've lost confidence in this poll.
I move to disolve this poll and we'll try again for the right answer, hopefully with less of a 50/50 split. Maybe we need a third answer that can hold the balance of power. |
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| oldraven |
quote:
Originally posted by snugs
Think "treadmill"..... I've moved on to sticky notes and paperclips, will still be 8-10 weeks before results are available though.
A treadmill relates to the movement of your feet, not your body. If your body is moving, then your feet are moving faster than the treadmill.
Saying the plane is moving has nothing to do with the conveyor. Saying it's wheels are moving only has a completely different meaning. |
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| snugs |
quote:
Originally posted by oldraven
A treadmill relates to the movement of your feet, not your body. If your body is moving, then your feet are moving faster than the treadmill.
Saying the plane is moving has nothing to do with the conveyor. Saying it's wheels are moving only has a completely different meaning.
Why do you think I said "Scratch that". ;) |
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| snugs |
quote:
Originally posted by JustinL
My first reaction was to vote no. But I want to change my answer to yes.
I've lost confidence in this poll.
I move to disolve this poll and we'll try again for the right answer, hopefully with less of a 50/50 split. Maybe we need a third answer that can hold the balance of power.
RECOUNT!!!! I promise a to reduce the amount of uncertainty associate with this problem fro 7% down to 5% if you vote for my option. :p
The third answer should be -In theory 'Yes', In practice 'Probably Not'- |
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| MrHeavyFoot |
quote:
Originally posted by JustinL
Maybe we need a third answer that can hold the balance of power.
Since the wheels/tires will be rotating twice as fast as they would on "stationary ground", the tires will blow out before the plane can take off. :p |
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| oldraven |
quote:
Originally posted by snugs
RECOUNT!!!! I promise a to reduce the amount of uncertainty associate with this problem fro 7% down to 5% if you vote for my option. :p
The third answer should be -In theory 'Yes', In practice 'Probably Not'-
Or 'Yes, only if you have really good wheel-bearings'. |
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| snugs |
quote:
Originally posted by oldraven
Or 'Yes, only if you have really good wheel-bearings'.
'and the tires aren't Firestones.' :p |
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| bigmack000 |
quote:
Originally posted by snugs
'and the tires aren't Firestones.' :p
lol |
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| scooby_dooby |
if the treadmill is moving at the same rate as the plane, the plane can not be moving forward. If it's not movig forward it has no velocity, can't create lift, how can it take off?
velocity = d/t, if distance = 0 velocity = 0 |
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| oldraven |
quote:
Originally posted by scooby_dooby
if the treadmill is moving at the same rate as the plane, the plane can not be moving forward. If it's not movig forward it has no velocity, can't create lift, how can it take off?
velocity = d/t, if distance = 0 velocity = 0
You must have missed the part where it said 'The plane is moving' too.
Seriously guys, plane and wheels are two different things. |
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| scooby_dooby |
| it also says the treadmill is 'moving' that doesn't mean teh treadmill is physically moving forward. |
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| JustinL |
quote:
Originally posted by scooby_dooby
if the treadmill is moving at the same rate as the plane, the plane can not be moving forward. If it's not movig forward it has no velocity, can't create lift, how can it take off?
velocity = d/t, if distance = 0 velocity = 0
Assuming no friction in the wheel bearings etc, what would hold the plane back from accelerating? The only forces acting on the plane are from the thrust, gravity and air resistance. The only thing that would happen is that the wheels would spin twice as fast as on normal ground.
If that's not working for you, imagine the treadmill is spinning at 100 mph and the plane is on it again with frictionless wheels. The body of the plane will sit still and the wheels will spin at 100mph. Once you turn on the jet engine the plane will move forward regardless of how fast the treadmill is turning.... the wheels will just have to spin 100mph faster than the true velocity of the plane. |
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| scooby_dooby |
| ahh you're right, since the wheels don't push the plane forward, they simply allow it to roll. So the thrust would move the plane forward and wheels would turn at double teh speed, gotcha ;) |
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| SilverZ24 |
quote:
Originally posted by JustinL
If that's not working for you, imagine the treadmill is spinning at 100 mph and the plane is on it again with frictionless wheels. The body of the plane will sit still and the wheels will spin at 100mph. Once you turn on the jet engine the plane will move forward regardless of how fast the treadmill is turning.... the wheels will just have to spin 100mph faster than the true velocity of the plane.
I'm pretty sure if I put a model airplane on my treadmill, and turned on the treadmill, the plane would simply fall off the end of the treadmill unless it had a way of powering itself to a speed equivilant to the treadmill. In which case it still wouldn't be moving compared to the air around it and I don't get how it could get off the ground.
Anyway, can someone post the actuall correct answer so maybe I can get my head around it. lol |
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| scooby_dooby |
quote:
Originally posted by SilverZ24
I'm pretty sure if I put a model airplane on my treadmill, and turned on the treadmill, the plane would simply fall off the end of the treadmill unless it had a way of powering itself to a speed equivilant to the treadmill. In which case it still wouldn't be moving compared to the air around it and I don't get how it could get off the ground.
Anyway, can someone post the actuall correct answer so maybe I can get my head around it. lol
That's because your model plane has no jets strapped to it's wings.
And actually, if you had frictionless wheels then model plane would not move.
There would be an insignifigant amount of friction caused by the wheels, but that would be totally overcome by the massive amounts of thrust provided by the jets. |
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| SilverZ24 |
| The question makes no comment about frictionless wheels though. It just says that conveyer will match the jets speed but in the opposite direction. To me that means the plane isn't moving. :dunno: |
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| ohonelude |
It WILL take off. The wheels have nothing to do with propelling the plane, it is the engines that provide thrust.
It will take off in the exact same distance as if there were no treadmill on the runway(assuming no friction). |
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| scooby_dooby |
Put it this way, IF it had frictionless wheels the plane would not move at all. The treadmill could go 1000mph, but the plane wouldn't move.
Now, it doesn't have frictionless wheels, which means there will be a small amount of force pushing the plane backwards, but only a small amount.
The thrust of the jet engines would completely overpower this very small amount of negative force, and the plane would move forward.
Just ask yourself, what is stopping the plane from moving forward? Nothing. Just a tiny bit of friction caused by the rotating wheels(which is what would cause your model plane to go backwards). |
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| ehos |
The answer is Yes, he will take off or..
"Manfred breaks ground, climbs a few hundred feet, then makes a low pass to see if he can terrify the spectators because they are Americans, descendants of those who defeated his countrymen back in 1918."
Confusion between ground speed vs airspeed. |
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| dc2696 |
quote:
Originally posted by ehos
The answer is Yes, he will take off or..
"Manfred breaks ground, climbs a few hundred feet, then makes a low pass to see if he can terrify the spectators because they are Americans, descendants of those who defeated his countrymen back in 1918."
Confusion between ground speed vs airspeed.
no,no...just general allaround confusion lol.:D |
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| ohonelude |
quote:
Originally posted by dc2696
no,no...just general allaround confusion lol.:D
He explains the conveyor runway a little further down the page. |
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| dc2696 |
quote:
Originally posted by ohonelude
He explains the conveyor runway a little further down the page.
lol i understand the situation, i was commenting on others posts:D |
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| oldraven |
quote:
Originally posted by SilverZ24
The question makes no comment about frictionless wheels though. It just says that conveyer will match the jets speed but in the opposite direction. To me that means the plane isn't moving. :dunno:
Think of what you just said. The Jets speed! This implies movement. |
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| SilverZ24 |
| I know, I'm just stubborn. :p |
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| scooby_dooby |
quote:
Originally posted by oldraven
Think of what you just said. The Jets speed! This implies movement.
Oldraven, your method of coming to this conlusion is flawed.
it's has nothing to do with the implied "movement" in the question. It has to do with the fact that planes don't recieve their thrust through the wheels, but rather from air thrust.
If a plane WAS powered by it's wheels, then regardless of whether the question stated the plane was "moving" it would be unable to take-off, since the treadmill would match the "movement" of the plan but in teh opposite direction.
So the phrasing of the question is totally irrelevant, what really matters is that the planes thrust is not provided by the wheels. |
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| SilverZ24 |
quote:
Originally posted by scooby_dooby
Oldraven, your method of coming to this conlusion is flawed.
it's has nothing to do with the implied "movement" in the question. It has to do with the fact that planes don't recieve their thrust through the wheels, but rather from air thrust.
If a plane WAS powered by it's wheels, then regardless of whether the question stated the plane was "moving" it would be unable to take-off, since the treadmill would match the "movement" of the plan but in teh opposite direction.
So the phrasing of the question is totally irrelevant, what really matters is that the planes thrust is not provided by the wheels.
If someone would have said that at the begining it would have made total sense to me. :thumbup: |
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| scooby_dooby |
quote:
Originally posted by SilverZ24
If someone would have said that at the begining it would have made total sense to me. :thumbup:
that simple eh!?
btw your car is fuckin hawt |
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| bigmack000 |
| iam right go by what i say :P hahaha :thumbup: |
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| S2KPWR |
If it was possible, the USAF would have it on their aircraft carriers by now.
And possibly all civilian airports. |
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| Talontsi96 |
Too bad I din't check out this thread earlier. It was such a silly scenario and so easy to analyze. The plane pushes itself by pushing air not by rotating the wheels on the ground. Since the airplane pushes the air to accelerate whether there is a conveyor on the ground or not makes no difference.
Similar type of problem. If youre on a sailboat and there is no wind and you had a big powerfull fan on the boat that would blow air on the sail. Would the sailboat move forward? |
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| oldraven |
quote:
Originally posted by scooby_dooby
Oldraven, your method of coming to this conlusion is flawed.
it's has nothing to do with the implied "movement" in the question. It has to do with the fact that planes don't recieve their thrust through the wheels, but rather from air thrust.
If a plane WAS powered by it's wheels, then regardless of whether the question stated the plane was "moving" it would be unable to take-off, since the treadmill would match the "movement" of the plan but in teh opposite direction.
No, it would match the speed of the wheels, not the speed of the plane, since that would be nil.
quote:
So the phrasing of the question is totally irrelevant, what really matters is that the planes thrust is not provided by the wheels.
Thrust doesn't create lift. The 'movement' of air over a wing does. Denser air under the wing vs. thinner air over the wing. You can't have this without movement. You can have four times the needed thrust, but you aren't going to take off if you're chained to the tarmac and sitting still.
Now thrust does create movement, so we're all good. ;)
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| PraxGTI |
quote:
Originally posted by snugs
Is it an african 747 or a european 747? :dunno:
We are the knights who say NIiii!!
We demand a Shrubury!!! |
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| HeavyEarly87T |
BAH!
Based on the information given the force is not relevant. If the conveyor were set up to counter the wheel speed created from any source, the plane would never move and lift would never be created.
Done deal…nothing more was given so nothing more can be said. |
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| oldraven |
quote:
Originally posted by HeavyEarly87T
BAH!
Based on the information given the force is not relevant. If the conveyor were set up to counter the wheel speed created from any source, the plane would never move and lift would never be created.
Done deal…nothing more was given so nothing more can be said.
But the plane does move, and that has nothing to do with the wheels. Read the riddle and pay close attention. They get you with the part about the conveyor moving at the same speed. It doesn't matter. They conveyor can be moving at twice the speed of the plane, in the opposite direction, but the 'plane' would still be 'moving' down the runway, powered by its engines (not its wheels), wheel bearings glowing red.
This is confusing way too many people. There is an answer, and the majority of people got it wrong. |
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| snugs |
quote:
Originally posted by HeavyEarly87T
BAH!
Based on the information given the force is not relevant. If the conveyor were set up to counter the wheel speed created from any source, the plane would never move and lift would never be created.
Done deal…nothing more was given so nothing more can be said.
lol, that's what my wife (who is smart and beautiful and might wind up reading this thread) figured too.
This is sort of a Newton's 3rd law problem. For the plane to not move there must be an equal and opposite force opposing the thrust of the engines. The conveyor belt isn't applying an opposing force to the plane, it is applying a force to the wheels of the plane which is causing them to rotate. The rotational motion of the wheels caused by the conveyors is not opposing the thrust of the engines, the sum of forces is not zero, therefore the plane will accelerate. |
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| JustinL |
quote:
Originally posted by oldraven
That's some crazy ass turbulence over the wing! :eek: |
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| oldraven |
quote:
Originally posted by JustinL
That's some crazy ass turbulence over the wing! :eek:
I may have the swirls going in the wrong direction. :blink: Hey, I don't have anything but MSpaint at home, and I wasn't about to break out Autocad Mechanical Desktop 2005 just for a five minute sketch. :p |
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| Talontsi96 |
| I can't believe that some people still dont get it and think that the plane would not take off. |
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| scooby_dooby |
quote:
Originally posted by oldraven
Thrust doesn't create lift. The 'movement' of air over a wing does. [/B]
Umm thrust does create lift. It pushes the plane forward thus creating lift.
The key idea in my post that you quoted was not how lift is created, but how a plane creates it's forward momentum. It's not generated through the wheels, if it WAS the plane would not take off regardless of the wording of the question. |
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| DeathBy240 |
This was posted on a physics forum (Who knew those even existed) and THE PLANE WILL TAKE OFF.
Like others said, the only thing the conveyer belt does is make the tires spin super fast, but there isnt enough drag/resistance in the tires and wheel bearings to slow down jet engines.
The tires would likely shred to pieces before takeoff, but in theory it would take off. |
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| oldraven |
quote:
Originally posted by scooby_dooby
Umm thrust does create lift. It pushes the plane forward thus creating lift.
The key idea in my post that you quoted was not how lift is created, but how a plane creates it's forward momentum. It's not generated through the wheels, if it WAS the plane would not take off regardless of the wording of the question.
No, thrust doesn't create lift. Try taking off in a wingless plane. |
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| Talontsi96 |
quote:
Originally posted by oldraven
No, thrust doesn't create lift. Try taking off in a wingless plane.
If the thrust to weight ratio is more than one, a plane with no wings will fly. Just look at rockets which are basically wingless.. Both of you are right in a way....The whole point is the conveyor has nothing to do with the plane's speed in this problem. |
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| youngbex |
| i think it will take off... |
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| oldraven |
quote:
Originally posted by Talontsi96
If the thrust to weight ratio is more than one, a plane with no wings will fly. Just look at rockets which are basically wingless.. Both of you are right in a way....The whole point is the conveyor has nothing to do with the plane's speed in this problem.
That's not lift, acutally, it's a different type of force (created by thrust). And planes ( a 747 anyway, not a harrier) don't have downward thrust, like a rocket. They have forward thrust, and rely on the lift created by the wings to get them off the ground.
By your theory, the plane would have to be standing on its tail. In which case, it won't take off. :D
http://en.wikipedia.org/wiki/Lift_%28force%29 |
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| Talontsi96 |
| This is getting ridiculous dont you think? and has no relevance with the original question. Technically a plane with no wings would have no controll surfaces (rudder, elevator, ailreons etc.) to steer the plane even if it would take off so I guess there is no point in arguing about that. Again that has nonthing to do with the original problem. |
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| ehos |
"My comment: Notice that the question does not state that the conveyor's movement keeps the airplane over the starting position relative to the ground, just that it moves in the direction opposite to any movement of the airplane."
Question: Does the 747 stay still on the belt? If in your mind you think the 747 stays still, it won't take off.
If in your mind, you think the 747 will still move forward, (airspeed vs ground speed) it will take off.
So, EVERYONE is right. Just how do you imagine it? (The original question doesn't state the 747 will stay still).
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| Talontsi96 |
| The whole point is that the airplane will not stay still on the conveyor because it is being pushed forward by air not the ground, therefore the people that think that it will stay still on the conveyor are not right.... |
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| CanadianSkyline |
We just argued this to the death on beyond. And the plane WILL TAKE OFF!!!!!!!!!!!!!!!!!!!! I thought people were smarter than this. Go read this thread on beyond and there are numerous explanations of why the plane will take off, and by the end we had everyone seeing it the same way (other than the voters who just voted rather than thinking about it). An airplane is propelled by its motors, the wheels are merely along for the ride.
http://forums.beyond.ca/showthread....threadid=110387 |
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| CanadianSkyline |
quote:
Originally posted by DeathBy240
The tires would likely shred to pieces before takeoff, but in theory it would take off.
No they wouldnt, aircraft tires are tested well beyond the real world extremes that they will experience, and the tires will only be moving exactly twice as fast as they normally would on a take off. Which is def. within their testing thresholds. |
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| CanadianSkyline |
quote:
Originally posted by ehos
"My comment: Notice that the question does not state that the conveyor's movement keeps the airplane over the starting position relative to the ground, just that it moves in the direction opposite to any movement of the airplane."
Question: Does the 747 stay still on the belt? If in your mind you think the 747 stays still, it won't take off.
If in your mind, you think the 747 will still move forward, (airspeed vs ground speed) it will take off.
So, EVERYONE is right. Just how do you imagine it? (The original question doesn't state the 747 will stay still).
That does not make sense. The airplane is being pushed forward by hundreds of thousands of pounds of thrust, and the little bit of extra friction the conveyer belt induces wont be enough to make the airplane stand still. Think about it this way, for the belt to move, the wheels of the aircraft have to spin forwards, and in order for the wheels of the aircraft to spin, the aircraft has to physically move forwards.....this is not a car, it is an airplane, and the wheels are merely along for the ride. |
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| Talontsi96 |
Ok this hopefully will be a good and very easy to visualize scenario for people who still don't get it.
Lets say you are on rollerblades on the conveyor that moves backwards. You however are holding on to a rope that is connected to a wall in front of you. The conveyer moves backwards however as you pull yourself forward with the rope you still move forward. The conveyor speed can increase and all it will do is increase the speed that the wheels on your rollerblades turn but it won't prevent you from pulling yourself forward with the rope.
The rate that you pull yourself forward wont even change much no matter what the conveyor is doing. The conveyor can be going in a backward direction etc..etc...and not really affecting the speed at which you will move forward while pulling yourself forward with the rope.
This is the same with the plane since its propulsion is done by pushing air not the ground. |
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| DeathBy240 |
quote:
Originally posted by CanadianSkyline
No they wouldnt, aircraft tires are tested well beyond the real world extremes that they will experience, and the tires will only be moving exactly twice as fast as they normally would on a take off. Which is def. within their testing thresholds.
That's good to know.:thumbup: |
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| scooby_dooby |
quote:
Originally posted by oldraven
No, thrust doesn't create lift. Try taking off in a wingless plane.
lmao...in a PLANE thrust is what creates lift.
Planes have wings. |
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| oldraven |
quote:
Originally posted by scooby_dooby
lmao...in a PLANE thrust is what creates lift.
Planes have wings.
You don't understand the concept of lift. Keep reading scooby. |
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| snugs |
quote:
Originally posted by CanadianSkyline
I thought people were smarter than this.
No, they really are far stupider than you give them credit for. :p |
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| CanadianSkyline |
quote:
Originally posted by scooby_dooby
lmao...in a PLANE thrust is what creates lift.
Planes have wings.
An airplane gets pushed (well pulled if you want to get technical about it) through the air by its motors. This pulling creats forward speed, which then allows the wings to do their job of creating lift. Im not really sure what your trying to say...... |
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| scooby_dooby |
quote:
Originally posted by CanadianSkyline
An airplane gets pushed (well pulled if you want to get technical about it) through the air by its motors. This pulling creats forward speed, which then allows the wings to do their job of creating lift. Im not really sure what your trying to say......
What I'm trying to say is simple, an airplane creates it's lift using thrust. Be it propellor, or engine, the only way to create it's lift is to use thrust to propel it forward.
I'm responding to OldRaven's statement that thrust does not create lift in an airplane.
Old raven I understand lift just fine, it's an EXTREMELY simple concept. Tell me, how does your plane create lift without any forward velocity? |
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| oldraven |
That's the thing. Forward Velocity through air, meaning air over and under a wing, creates lift. Thrust creates forward velocity, not lift. You're getting the two confused as though they were the same thing. Thrust is a force moving in the opposite direction of forward velocity.
The only way thrust could create lift is if the jet was directly in front of the wing, and blasting so much air passed the wing that it would then have lift.
Anyway, airspeed is not thrust. Thrust creates motion, it is not motion in itself. |
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| oldraven |
On a GM truck board (don't laugh) someone tried to post this question, but instead of copying the actual riddle, he typed his own understanding of the riddle.
Imagine a plane is sat on the beginning of a massive conveyor belt/travelator type arrangement, as wide and as long as a runway, and intends to take off. The conveyer belt is designed to exactly match the speed of the wheels at any given time, moving in the opposite direction of rotation.
Now, by saying "designed to exactly match the speed of the wheels" he completely fucked up the question, and now that thread is on it's fifth page. I felt like I was stuck in a tilt-a-whirl trying to explain to these guys that there is no answer to ^that version of the riddle. It's an impossible situation, yet the guys who believe the plane won't take off are still trying to explain why it won't. |
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| snugs |
quote:
Originally posted by oldraven
On a GM truck board (don't laugh)
<snicker snicker snicker> |
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| oldraven |
quote:
Originally posted by snugs
<snicker snicker snicker>
Laugh it up, Mr. Mustang board.:mad: |
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| snugs |
quote:
Originally posted by oldraven
Laugh it up, Mr. Mustang board.:mad:
Hey I wasn't laughing, you specifically said NO LAUGHING! :mad:
I should post this over on svtp and see how long it takes before one of the wingnuts blames the plane's inability to take off on liberals. :p |
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| scooby_dooby |
quote:
Originally posted by oldraven
That's the thing. Forward Velocity through air, meaning air over and under a wing, creates lift. Thrust creates forward velocity, not lift. You're getting the two confused as though they were the same thing. Thrust is a force moving in the opposite direction of forward velocity.
No I never got the two confused. Sorry but you're basically calling me an idiot at this point, like I don't know the difference between thrust and lift.
You just took me literally, and completely out of context.
I specifically said in a PLANE thrust is what creates lift, you responded with "no. wings create lift", that's completely ignoring the context of my statement, I included the word 'plane' for a reason, planes have wings. Although the shape of the wing is what directly creates the lift, the thrust is what really creates it (indirectly) it is what allows the wings to generate their lift.
I didn't think I needed to spell the entire thing out.
Thrust creates forward velocity, which when combined with the shape of a wing, creates lift. aka Thust creates lift in a plane (note the word plane, that's context).
So....what were we arguing about again? |
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| snugs |
quote:
Originally posted by scooby_dooby
So....what were we arguing about again?
You were calling each other stupid and making silly faces at your computers.
I just posted this on one of the cobra boards, hilarity is ensuing. :D |
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| ehos |
| It won't take off, it's not possible due to physics. |
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| snugs |
quote:
Originally posted by ehos
It won't take off, it's not possible due to physics.
You won't graduate, it's not possible due to physics. :p |
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| JustinL |
quote:
Originally posted by snugs
You won't graduate, it's not possible due to physics. :p
Which board? I want to go watch! |
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| oldraven |
quote:
Originally posted by scooby_dooby
So....what were we arguing about again?
Nothing, aparently. If you think someone's finger puts a bullet hole through a target, and not the bullet itself, then yes, thrust creates lift.
It's indirect, and not the true source of lift. That's all I'm saying. You can't move without thrust, and you can't take off without movement, but thrust, in itself, doesn't create lift.
At this point I'm repeating myself and you're getting insulted, for some reason. I'll leave it at that.
p.s.
I'm not calling you an idiot. You're arguing physics with logic. Why would I think you're an idiot? |
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| ehos |
| Ok, you convinced me. It will take off. |
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| JustinL |
quote:
Originally posted by snugs
http://www.svtperformance.com/forum...age=1&pp=25
8 pages in under 16 hours... and still going. :lol:
So funny, yet so stupid.
You know what's funny are the guys who come in around page 9 and say something like this: "Now I haven't dun gon an read any of the pages up to now, but that thar plane aint gun fly. No way no how!"
You mustang guys crack me up :p |
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| chris f |
| ok, so it will take off, i thought it would not, if you took the tires out of the eqation and had the plane "sliding" on the belt then no it would not take off |
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| oldraven |
quote:
Originally posted by chris f
ok, so it will take off, i thought it would not, if you took the tires out of the eqation and had the plane "sliding" on the belt then no it would not take off
There's nothing in the riddle that says the wheels have to be spinning at the same speed as the conveyor, so there's no need to drag them at all. :) |
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| MightyMidget |
| won't...no lift = no fly |
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| Talontsi96 |
quote:
Originally posted by MightyMidget
won't...no lift = no fly
Oh..Boy...not another one.... |
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| MightyMidget |
quote:
Originally posted by Talontsi96
Oh..Boy...not another one....
yup another one!! |
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| Talontsi96 |
| Since when does a plane that moves forward at the normal design speed generate no lift? hmm? |
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| ae1969 |
| The svt thread is HILARIOUS! |
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| oldraven |
quote:
Originally posted by ae1969
The svt thread is HILARIOUS!
quote:
Whoever said that the aircraft will take off has absolutely no clue about basic physics. As other's here have previously stated, an airplane uses it's wing to generate lift. No relative wind = No fly, sorry guys...
BTW, I am a pilot.
:lol: Whoever gave you your licence, I'd ask for my money back. |
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| GOT BOOST |
quote:
Originally posted by DeathBy240
A plane (747 passenger jet) is sitting on a runway that can move (some sort of band conveyor). The plane moves in one direction, while the conveyor moves in the opposite direction. This conveyor has a control system that tracks the planes speed and tunes the speed of the conveyor to be exactly the same (but in the opposite direction).
The question is:
Will the plane (747 passenger jet) take off or not?
Hi Deathby240,
This is a loaded question with many variables. Does the conveyor belt change speed and respond at the precise moment the aircraft changes speed? Is there a time delay between responses the aircraft changes speed, the time the conveyor senses the change and compensates for it? What is being calculated for the conveyor belt speed. Ie wheel rating, or is there a mathmatical equation that is calculated based on the ammount of thrust the engines are putting out to compensate and increase the speed of the belt to match the speed or calculated speed that will result from the thrust?
I would say that the aircraft would not take off as there would not be enough thrust and movement to have the enough air flow over the wings to create enough lift. If two objects are moving in the same direction as in your example the real speed would be zero. Ie) If you are spinning your tires on ice. Your speedo could be reading 120 km/h but if your car is not moving, you are not travelling that fast.
Regardless how fast the wheels are travelling on the belt, the airspeed travelling over the wings would not be the same.
I believe the plane could take off if it were equiped with engines that would allow the aircraft to take off in a vertial position with the aircraft body still parallel to the ground. Then it may be done.
However if there were a malfunction in the belt causing the convery to slow down, the plane may be able to take off as it may infact have enough wind speed passing over the wings to allow it to lift off.
Alright.......... I will quit my rambeling now :D
Mike Nikolai |
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| JustinL |
Yeesh they're coming out of the woodwork!
It takes off no problem. |
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