The Elders' House of Pain
Public Forum => Talk Back => Topic started by: flintlock on December 08, 2005, 11:38:11 AM
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A guy I work with just pulled this of another forum and asked me. I said no, but I'm no physicist and it seems I'm in the minority. Thoughts?
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 plane's 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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no because its not really moving and its not getting enough air to lift the wings.
Steve
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Everythings relative. Good 'ole Einstein.
Think about the speed of the airplanes wing relative to wind speed. Since the plane is not moving relative to the ground, and hence, not relative to the wind, the wind speed over the wings would equal (or approximately) zero. Therefore, with zero wind speed, there would be zero lift, and the plane would not lift off.
If this worked, they wouldnt need aircraft carriers to launch jets at sea. =)
.phaeton
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Absolutely not. Like adder said. The wing give the plane lift via fluid dynamics. There are two schools of thought there. One has to do with deflection of air causing phyical lift, i.e. a normal force, and the other has to do with differences in fluid (air) velocity causing higher pressure under the wing, lower pressure above the wing causeing the material between the two local pressure zones (the wing) to lift up.
The forward motion of the plane starts the process of creating relative air movement. Once you're in the air, the forward thrust helps maintain altitude which is why pitch is important for fuel efficiency and airspeed.
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Depends.... are any of the passangers morbid? :wink:
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no because its not really moving and its not getting enough air to lift the wings.
Steve
That's what I was thinking, but then I get another e-mail this morning because I demanded an answer and below is what I got. The guy giving the explanation seem like a bit of a dick, nontheless, his explanation seems logical. I'm bold typing what I think is the key point. Maybe the question is flawed becuase it uses the term "speed." I know jets use thrust to move, who doesn't, but I interpret speed as a way to measure thrust. Thoughts?
When I read the first page of this thread I was amazed that there would even be a disagreement on this topic. The answer is so obvious I thought it wasn't even worthy of a discussion, much less a debate.
First, off let me preface my statement on this as follows: I served on the faculty at both Ga. Tech and Washburn University teaching Physics and Mechanical Engineering and Engineering Science and Mechanics. Besides working as an Engineering Scientist in the private sector, I was also a senior consultant at NASA JSC Mission Control.
I am 100% absolutely beyond any and every question totally confident that my answer is correct. Further, for those who think differently but know a little about how airplanes work, I can prove it with a very simple mental exercise.
So, without further delay, let me finally and definatively answer the question:
THE PLANE WILL TAKE OFF.
Why? Because I'm also an attorney who know how to READ CAREFULLY!!!
Let's carefully consider the question:
"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)."
I see nothing in this statement that says the plane remains stationary relative to the ground. (As many assume. And in which case the plane would not take off. This is why this is a trick question!!!) To the contrary, the statements says the motion of the converyor is relative to the "planes speed", not its thrust. Thus, if the plane isn't moving, neither is the conveyor.
If in fact you could create such a runway, the plane would accelerate and move forward just as it normally would in a normal take off (with a minimal reduction in acceleration caused by the increased resistence of having to spin the wheels and tires up to twice the normal speed. And when it got to the normal take off speed relative to the ground (and twice that speed ralative to the conveyor) it would take off normally.
Talking about physics consider the following: Force = Mass * Acelleration
If those jet engines are at max thrust, the mass of the plane is going to accellerate forward unless there is an opposing force in the opposite direction of equal strength to oppose it. The force of the conveyor on the wheels would not supply such a force. Thus the plane WILL move forward, even as the conveyor accelerates in the opposite direction at the same rate. And since the plane accelerates almost as quickly as it normally would, it will reach and exceed the stall speed and be able to lift off.
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if you do that you'd have a lot of busted tires... good luck on the new landing.
Steve
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ok flint. That guy is obviously a liar about his background. Thrust is a word for work done by jet engine. That's all. Put an engine on a car, does it fly? no.
He's talking about acceleration. what is acceleration? it is instantaneous velocity. Velocity per unit time. Rate of increase in velocity. He is calling thrust accelleration in his post. However, it the conveyor is to match speed (velocity) at all moments, it must match accelleration too. Thus, the mass cannot move. There is no relative momentum transfer. the belt has "thrust" in the opposite direction of the plane. net zero.
Now, this asshole thinks by calling himself the king of england, he's gonna get free tea. well, fuck him. :)
He obvously doesn't understand how a plane flys let alone the laws of Newtonian physics. I'd bet he was an english major in high school. Now he just sits around his mom's house eating pop tarts.
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well if his theory was to work, the tires are already rolling backwards... now the weight of the plane moving forward would make the wheel move forward which means them tires are gone from all the friction.
Steve
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look, the tires will not be damaged at all. not even the bearings, well eventually they will breakdown. When planes land, they're putting shitloads of force on the gear, and they don't blow up, always..
Rolling friction is the only friction the whells will exerience, which is extremely minimal. The forces are translated into angular forces since the wheels are round. It's tangential, and the rubber has enough of a coefficient of frictrion to go pretty damn fast before it completely wears out. It's more likely to blow out due to angular momentum (centripital force) pulling it off the rim.
That guy doesn't have a theory. All he is ... is a pathetic excuse for a psuedointellectual. Oh yeah, we believe you lawyer man! lol. I mean 3 inch dick man. ;p
Now, someone tell vergas to stop posting that crap.
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To begin my explanation, I must state my background to install an element of leetness. I am currently attending AP physics.... so I've got props on any fag with a Ph. D in physics. Also if all of my calculations are correct, I'm almost to the point where I've figured out how to rip space time. Also I am President of three different countries, so my answer to this question must be absolutely, 100% correct.
But anyway, I don't know about you guys, but this shit fucks with your head. The guy is a douche bag yes... but i think he's right. I'm not going to go into a drawn out physics answer and what not, because I have much better things to invest my time into, such as finishing my time travel theorems - instead I'll just use some logic. The plane is powered by jet engines, not the wheels. Is it possible that the jet engine will move the plane regardless of how fast the ground is moving opposite? Wouldn't it just make the wheels spin twice as fast as if it were taking off normally? I think the plane would still have a forward motion because the net force is created by the simple action/reaction caused by the jet engines, and not by the friction on the ground. Like i said, not totally sure if my thinking is correct... but i think the plane would still be moving forward regardless of the surface.
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to answer you shortly, no.
do a block diagram for this one.
remember. the plane flys due to phenomenon of fluid dynamics. movement of air past the wings.
when the plane is on the runway, how is it held up when it's not moving. it's gear.
so, when the jets are fired up, and you get some forward movement, where is the energy from the jets being transfered.
That's right. the ground. the energy will eventually be transfered to the wings, but not until you hit that critical point to where you start creating lift.
so, if the runway starts moving backwards, it opposed, or absorbs, the energy transfer of the engine.
fix the plane to the grond so it can't move. turn on full thrust. what happens.
one step further. make it so the plane is fixed by a giant shear pin some three-ten feet of the ground, that is it will break free at some give force on the pin. Make that force the maximum force that the plane can do. Obviously the plane can fly when its at full power. So, the pin breaks, the plane is ten feet off the ground at full engine on. what happens? the plane pitches down and crashes. The guy from flints post is on the ground cause he believes it will fly, but you know what...now he's dead.
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Instead of replying to that completely erroneous answer, which still falls short of my answer... I shall show you this: this is what the reaction of my family was when they tried to undersand your answer.... because its totally false
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J/K THATS NOT MY FAMILY GOT YOU GOOD BITCHES.....
....its just the average Kenyan of year 2005
still though, you're wrong :flamed:
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Kaneda -A+
Cole, I expected so much more out of you man. Put down the bong. Your physics professor want to see you. He said something about tearing up your diploma.
Riddle me this batman - how do rockets/thrusters work in space if there is no ground to transfer energy to???
Rockets, jet engines and cole all work off the same principle... expanding hot gas. For every action, there is an equal and opposite reaction. The expanding hot gas from the jet engines will THRUST the plane (Thrust - v. to push or drive with force) relative to the rest of the earth and atmosphere (which is not moving with the conveyor). This force will greatly exceed any drag imposed by the conveyor and wheels. Therefore, the plane will move forward, accelerate, and when it reaches sufficient speed, be able to take off.
Put a jet engine on a car -does it fly? no. Does it move? yes.
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The plane isn't moving, so it will never be able to take off.
Think about if you're on a treadmill, the faster it goes, the faster you run, but if you jump in the air,
you're not going forward, you'll just go up and then down in the same place (and probably get seriously injured)
'_'
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the treadmill example doesnt compare becuase your feet are the only source of propulsion.
Imagine this... belgian in a giant slingshot, wearing rollerskates on said magical conveyor.... what do you think (hope) will happen?
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Finally someone else agrees w/ me other than the physics doctor/ NYC lawyer.... Drop kick, get me in TE just for being smart.... and i'm only 18
did i mention i'm about to experience time travel?
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the treadmill example doesnt compare becuase your feet are the only source of propulsion.
Imagine this... belgian in a giant slingshot, wearing rollerskates on said magical conveyor.... what do you think (hope) will happen?
i was waiting for someone to use this example. Drop. nothing will happen because the conveyor has to ove fast enough to counter all motion caused by the slingshot. It's part of the assumptions in the beginning of the problem.
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Kaneda -A+
Cole, I expected so much more out of you man. Put down the bong. Your physics professor want to see you. He said something about tearing up your diploma.
Riddle me this batman - how do rockets/thrusters work in space if there is no ground to transfer energy to???
Rockets, jet engines and cole all work off the same principle... expanding hot gas. For every action, there is an equal and opposite reaction. The expanding hot gas from the jet engines will THRUST the plane (Thrust - v. to push or drive with force) relative to the rest of the earth and atmosphere (which is not moving with the conveyor). This force will greatly exceed any drag imposed by the conveyor and wheels. Therefore, the plane will move forward, accelerate, and when it reaches sufficient speed, be able to take off.
Put a jet engine on a car -does it fly? no. Does it move? yes.
2 things. the car moves. move the ground in the opposite direction. where is the car. the plane is the same, but with a different name.
second. we all know how a rocket works, but it is irrelevant. Jets don't work off hot gas. They compress air, creating a pressure difference front to back. It is only heated from engine exhaust and is negl. in the overall. you could also look at the compression as a rapid increase in air velocity pushing the engine. The same "two schools" of though in the wing apply here too.
FUCKING ROLLING FRICTION IS NOT A LOT OF DRAG. and i never said it was .olol.
It does not matter what the source of propulsion is. The problem is set up to trick you. All that matters is motion. Now, stop calling me retarded. Submit a formal proof. Maybe I'll do one too.
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Lol i was never calling you retarded cole :lol: ...but wow, I still dk which one to believe
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We need more threads like this
there are two great things in life... jocks fighting jocks and geeks fighting geeks
and let me tell you, you guys don't play varsity football
Now if you want a response from a business person (ahem myself) I know nothing about all the following information and theories and what not, but I do know how to read and justify reasonable doubt. Dropkick's theory (or that weird dude) seems to be the right answer after carefully reading both arguements (and after laughing for like 30 minutes of that picture kaneda put up!)
Sorry, its just how it is.... i always pick winners, im like fucking vegas over here
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Cole, I didnt call you retarded, but i am saying you are still wrong. Speed and movement are relative. The problems states that the conveyor will match the speed of the plane in the opposite direction. If the plane is not moving, then neither is the conveyor. If the plane were flying through the air, and so was the conveyor, then they would not be moving relative to eachother, but to the rest of the world they are. Back on the ground, To keep the plane from moving, there would need to be an equal force in the opposite direction of the thrust of the jet engines. The only force the conveyor can exert on the plane itself is friction. Lets just say the plane was moving at 500 mph, so the conveyor is going 500 mph in the opposite direction, that would be 1000 mph net wheel speed. I dont think that the friction is sufficient to balance the thousands of pounds of thrust generated by the engine. Do your force vectors. then think about writing a proof.
Get your treadmill and crank it all the way. Then get a toy car. hold the toy car on the treadmill. can you push the toy car along the treadmill? I knew you could.. heres a cookie.
To say that a jet engine works off of hot gas is a simplificaton. To say that it works off compression is incomplete. Let me explain. A jet engine, is an internal combustion engine similar in operational theiory to your cars engine. all internal combustion engines are essentially air pumps. They mix air and fuel, compress the mix, ignite the mix, and the power is derived from the expanding gas of the combustion - not the compression.
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your right Priv.. I dont play varsity football. But I think I know someone who should :-D
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the treadmill example doesnt compare becuase your feet are the only source of propulsion.
Imagine this... belgian in a giant slingshot, wearing rollerskates on said magical conveyor.... what do you think (hope) will happen?
I would hope for cookies...
'_'
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Get your treadmill and crank it all the way. Then get a toy car. hold the toy car on the treadmill. can you push the toy car along the treadmill? I knew you could.. heres a cookie.
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 plane's speed and tunes the speed of the conveyor to be exactly the same (but in the opposite direction).
Now, if you push the car, it's velocity is greater than the velocity (in the opposite direction) of the conveyor. Thus that is not valid. It is a different problem. You are confusing the issue of inertial observation verses non-inertial observation. To the inertial observer, the plan will appear to be stationary. to someonestanding on the tarmac, the (non-inertial observer), the plane is moving very fast.
The issue is that the plane is not catching any wind, so it will not fly. A plane needs the movement of air. It needs a certain amount of air molecules to bombard the leading edge of the wing. Those air molecules move faster over the top of the wing, slower under, creating a pressure difference.
Remember that the speed of the wheels will be directly proportional to the radius of said wheels. The rolling friction is so negligable that for all intents and purposes you can ignore it. But it could be calculated if you wanted to but you'd need to know more about the bearing system -either way you'd be making assumptions without direct empirical data.
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DOLPHINS BE SO SMART
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Now you are just spouting bullshit. Stop focusing on the wheels and velocity, becuase they dont move the plane. The intertial frame would be what the outside non-inertial observer sees, not the observer itself. So the frame would include the plane, the conveyor and the ground. An intertial observer would be inside the plane, where yes, the seats and what not are not moving relative to him. Newtons laws always will and apply, because they are... laws. 1st law -body in motion or at rest will remain that way unless there is an outside force acting upon it..in this case the outside force is the thrust of the engines or hand pushing the toy car. Other forces at work are gravity, the normal force, and drag from the planes wheels on teh conveyor, and drag from the surrounding air. Since these forces will not cancel eachother out, there is a net positive force acting on the plane. 2ND law - F=M*a we know we have a net force, and the planes mass is constant, therefore, a > 0.
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I still think this all could be simplified into : the plane will move forward because of the action/reaction of the engine, regardless of the wheels spinning twice as fast due to the runway.
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Cole, you are one of my favorite TE members by far...but I must tell you...the plane will take off. Drop is right. It will move down the runway (relative to the earth) at the same rate (minus friction losses associated with the wheels) just as if it were on pavement. The jets are moving the plane relative to the earth independent of the wheels.
Kaneda, that pictue made me laugh out loud. Funniest shit I've seen in a while. I don't care that you are under 21, you are gonna get sponsored for this clan on that picture alone. :headbang1:
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Lol thanks Train.
I like how Drop is getting all the credit for his answer...
I agreed with the a-a-tourney f-f-f-irrst :cry:
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Drop is an old roomate of mine. He gets credit before some attorney. :lol:
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The jets are moving the plane relative to the earth independent of the wheels.
no it's not. it's moving it relative to the conveyor and the earth....
replace plane with a car and it is the same answer the method of forward propulsion is trivial.
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i eat clay :blob:
Hilarious.
And yes, iut will fly. While the conveyor belt is moving in the opposite direction, the plane is still moving. It appears to not move, and you would think that it would be stationary, but I don't think it would.
While the plane is going against the coveyor, it still, is in fact, accelerating. Think of it like this. If you run outside, in the wind, you will feel it. (duh). Now place a conveyor belt (reeeeally long one) outside and run on it. Guess what: the wind is still going past you at the same speed. Therefore, the plane, hypothetically, should be able to lift off, as the wind is still passing it, and, in theory, it is making progress towards the wind.
Of course, I'm no technical expert, or genius, but that is just my 2 cents.
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OMFG no it won't.
Jesus christ people!
First Drop.
Then Night.
And now Mathius.
Who's next?
Try it this way guys. Turn the plane around and turn on the conveyor. The plane shall start moving with the conveyor. If the conveyor goes fast enough, the plane will take off (and since it's not powered subsequtially touch down). So....
matching speed in opposite direction = zero net speed. I don't give a damn how you look at it. that's logic. Now without the air moving around the wing, you cannot fly the plane. Unless it's a UFO.
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Before the plane flys, it will will act like a car, it's propulsion system is just different. IF the runway moves along, matching the speed (thus the acceleration too since it is matching instantaneous velocity) the plane never gets up to air airspeed where it generates lift. Think of it this way, once lift is generated, the tranfser of energy changes from engine to ground to engine to air. Actually, it is arguably engine to wing.
I think too many people think of this problem as hey, if a plane is flying, and its wheels touch down on a conveyor matching it's speed in an opposite direction, it can still fly. Or, they argue that the plane is flying in air. The engines act upon the air. It's not like a car where the engine turns the wheels and the engery transfer is tire to ground. Well, I've got one for those people too. Wrong! The energy transfer is from Jet Rocket Ion Propulsion Fart Power to the ground in the plane too. One word: Gravity. In normal operation, the plane goes fast enought to generate lift and overcome gravity. On the conveyor, this of this discretely. For every one "node" forward the engine pushes the plane forward, the conveyor pushes the plane back. To the observer off the conveyor watching from afar, there is no net movement, but the tires spin twice as fast. Thus the plane will not ever gain any velocity, and no flyie flyie fo' the poor little planey.
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cole is sitting at home... maybe watching tv... and then boom, another possible reason as to why it wont fly pops to his head...dilemma is does he leave the tv to go post it or does he just write it down on a piece of paper to then transfer it to the forums after the show.
We can clearly see that due to the excessive double posting by him that his favorite tv shows are not on
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Ok. I retract my statements. All of them except the whole DOLPHINS BE SMART and shit.
plane moves forward 40 miles per hour. Conveyor moves backwards 40 miles per hour. Planes groundspeed is now 80 miles per hour relative to the conveyor, but outside the inertial frame, the conveyor is moving at the same speed but opposite of the plane. Plane's wheels are still going 80/2*pi*r but no problem. The Plane is still moving forward since the engines are using the air to cause movement which is not attached to the conveyor. Basically the cause of movement is outside of the conveyor-plane frame of reference, so it is not the correct reference to use. So the plane does fly.
It is a very good thing I have no shame. This character trait allows me to be wrong many times and still learn from my mistakes. I don't know what the hell I was thinking. My brain is fried from too much WPI Stratton hall crap. Now back to Chapter 10 - Brownian motion. woo hoo.
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priv. you ruined my triple post.
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I'm afraid to take a stance on this one. Instead, I'll post a question:
Tie the tail of a plane to a concrete block. Now two assumptions - the rope/cable is infinitely strong and the block will not move under infinite force. So, if the engines of the plane fire up, will the plane drift up in the air?
This is the same problem re-worded and I think, at least to me, it is a little simpler to thing about. I know my answer but I'm not posting it...I'm too wimpy for the critics on this forum!!!
Maybe I'll hit the books a little later and post something but for now - nada.
:mrgreen:
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LOL...
http://forum.physorg.com/index.php?s=de677ccf0a75800be03ff934d999b080&showtopic=2417&st=0
You figure it out...
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In your example Spike, the plane will not move. You see, the rope and anchor are in the same inertial frame as the plane. The rope directly opposes the force the engine puts on the plane. In the conveyor example, the conveyor exerts force on the wheel, and the plane exherts force on the wheel, but those forces are additive. the engine puts force/work on the plane, but there is nothing opposing it. the wheels are not powered, that is they do not power the plane. The plane powers the wheels sort of. That's where I was confusing myself. The conveyor just mkes the wheels spin two times faster.
Now another way to change the problem would be instead of a conveyor, you have a wind tunnel. The wind velocity opposes the plane directly proportional to the plane velocity. What happens?
lol. The plane takes off sooner. Basically it seems that planes are easy to get airborn, and the Wright brothers are hacks, just like everyone else from Indiana and Ohio! That's right Wolvey*pie*, yum.
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Nope - the conveyor and the wind tunner are completely different. The wind tunnel will cause lift, as the air is cleary moving in relation to the wing.
My take on the conveyor case is the plane will not get off the ground. What we are talking about is instantaneous velocity/speed of the wing in relation to the air - that is what the conveyor is adjusting to. The average velocity/speed of the air with respect to the wing is zero, thus zero lift. Just think about a plane - it doesn't get in the air the second it starts moving - it takes a significant trip down the runway with a lot of acceleration. You can't have acceleration without a change in velocity - the only things accelerating are the belt and the wheels and the wheels are accelerating in a circular motion. The minor velocity changes as the conveyor adjusts are not enough to give the plane the lift it needs.
I'm no brain surgeon, but I'm far from a dummy - I aced every Physics course I took - 2 at Tufts and 6 at WPI. But this doesn't mean I'm right either. I looked on the web and there are dozens of forums with hundreds, maybe even thousands, of posts regarding this exact problem. The key is - who's got the right answer?
:mrgreen:
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Guys...Cole has spoken.
He retracrted his earlier statement, and now says the plane will fly.
Hah. So, that has to be the answer, cus, Cole is smart (or at least sounds like it).
The plane will fly.
Besides Dropkick, Nighttrain, Cole and, Hey, me. :-D
Some Smart dudes right there (well, maybe except for me.)
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Nope - the conveyor and the wind tunner are completely different. The wind tunnel will cause lift, as the air is cleary moving in relation to the wing.
That was my point.
I was thinking the same way as you. However, you're neglecting to consider the moion of the plane to it's surrounding air, which is like the rope. The conveyor is outside of the inertial frame.
If you were inside the plane. Fire up the engines. you'd get thrust from the engines which are dependent of the air, and independent of the ground. So, the conveyor doesn't even matter. If you didn't look at the ground, you wouldn't even know that the conveyor was moving.
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I'm still not buying it. Anyone have a jet and a coveyor belt we can borrow?
The air through the engines/turbines is moving, obviously, but this air isn't the air that causes the lift. The engine moves the plane - the plane moving through the air causes the lift. The plane can't move, because the conveyer is preventing it.
Enough said from me. I find these types of posts annoying. Flint - wtf is wrong with you!!!!!!
:mrgreen:
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Guys...Cole has spoken.
He retracrted his earlier statement, and now says the plane will fly.
Hah. So, that has to be the answer, cus, Cole is smart (or at least sounds like it).
The plane will fly.
Besides Dropkick, Nighttrain, Cole and, Hey, me. :-D
Some Smart dudes right there (well, maybe except for me.)
Omg... can we please recognize Kaneda... I recall him being the first one to disagree with everyone else :cry:
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Guys...Cole has spoken.
He retracrted his earlier statement, and now says the plane will fly.
Hah. So, that has to be the answer, cus, Cole is smart (or at least sounds like it).
The plane will fly.
Besides Dropkick, Nighttrain, Cole and, Hey, me. :-D
Some Smart dudes right there (well, maybe except for me.)
Omg... can we please recognize Kaneda... I recall him being the first one to disagree with everyone else :cry:
AND KANEDA TOO!!!!
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The air through the engines/turbines is moving, obviously, but this air isn't the air that causes the lift. The engine moves the plane - the plane moving through the air causes the lift. The plane can't move, because the conveyer is preventing it.
:mrgreen:
That's just it! The conveyer is not doing that. it could, but since the wheels are not transfering power i.e. work to the plane, having the conveyor match the speed of the plane is not enough. The conveyor could concievably stop the plane from moving, but it would have to move much much faster than the plane.
And the air is the same air.
Oh, and kaneda - no recognition, cause you didn't explain yourself very well. ;P
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I guess we can get rid of runways for takeoffs then. Don't think so - only the Harrier uses it's engines for initial lift at takeoff.
Here's a lesson for you (http://www.aeromuseum.org/Education/Lessons/HowPlaneFly/HowPlaneFly.html):
"The four aerodynamic forces that act upon an airplane in flight are lift (the upward acting force), weight (or gravity, the downward acting force), thrust (the forward acting force), and drag (the air resistance or backward acting force). These four forces are continuously battling each other while an airplane is in flight.
Gravity opposes lift, thrust opposes drag. In order to take off, the aircraft's thrust and lift must be suffucient to overcome its weight and drag. In level flight at constant speed, thrust exactly equals drag and lift exactly equals the pull of gravity. To land, an aircraft's thrust must be reduced safely below its drag, as its lift is reduced to levels less than its weight.
Lift is the aerodynamic force that counteracts gravity and holds an airplane in the air. Most of the lift required by an airplane is created by its wings, but a certain portion is also generated by other parts of the aircraft, such as the fuselage.
Thrust is the force created by a power source that overcomes the airplane's aerodynamic drag (its resistance to passing through the air) and gives it forward motion. This force can either "pull" or "push" the aircraft forward, depending on the type of power source used. Common types include reciprocating (piston-powered) engines driving propellers, and jet engines."
The air is not the same - I love to say it - you are wrong. The air that the engine acts on, via thrust, overcomes drag. The air moving over/under the wing creates lift and overcomes gravity.
Updated - You, know, I'm starting to think the plane will fly...after some serious thought - I may actually buy into the fact that all that the conveyor does is make the wheels spin twice as fast. Better have some damn good bearings. But, I'm still right about the air Cole...:)
:mrgreen:
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I'm bringing this up in my physics class tomorrow. My teachers pretty $$... so we'll see what he has to say
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spike about the air. When i said that the air is the same, I mean the body of air that the plane is occupying. I know how a plane flys. and what you said about the drag, the conveyor is creating a minimal amount of extra drag. The amount translated into the plane would have to depend on the coeff. of friction of the bearings and tires, and size and mass of the tires, etc.
an engine will not fly without a wing, so i now get what you were saying about the air not being the same. What I was refering to was that the air that ineracts with the wing and the air that interact with the engine is in the same inertial frame.
So basically this question doesn't really give enough information. But, if assumptions of a normal plane are made it will take off. If the bearings and tires can create enough drag to keep the plane from going to takeoff speed when the conveyor matches the planes speed .... yada yada yada.
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Yea physics teacher said the plane will move forward regardless of the wheels. Wheels are just used to reduce friction, jet engines are what create the acceleration. So... it'll move forward, therefore fly, as I said...
i still win
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This thread is so damn funny. I think we need to make it a sticky so all of our visitors can see how leet our Engineers are. For all you guys that are too lazy to read a four page thread you should make an exception on this one.
Cobra has my favorite reply in the history of the clan.
i eat clay :blob:
Cole, the smiley plane is pretty cool too, but I have to go with Cobra.
But my question is this...without all the math beacuse I don't know jack about that.
Can we get away with... max thrust (MT) minus max weight (MW) minus max drag (MD) would equal max speed (MS)?
So for this example we can say MT - MW - MD = 350 mph (MS) because we are talking about speed which is the result of everything else adding, subtracting, coefficienting and whatever.
If the belt can match 350 mph, however many rotations of the tires and belt it takes, (You can't even measure the belt in terms of speed anyway can you? it would be like RPMs or something) wouldn't that keep the plane on the ground? I still think the question is flawed.
Oh yeah and to everyone that got sucked into reading this, you're welcome!
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Ok.
So...the plane fly's
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Whats important to note here is that I was right, and that Cole was wrong. (Kaneda, srry dude, but I get all the props.. 1. becuase Im an owner, 2. you only quesitoned old King Cole.. I kicked his ass.)
I AM KING OF THE MOUNTAIN, BITCH!!!!!
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yeah, you you probably cheated by using google! I challenge thee to a probability problem!
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its funny cause all of that doesnt matter if you attach the engine of a Harrier jer onto that 747..... cause it would take off straight up...
I decree spike the winner of the battle of wits... cause he was the first to mention it...
there.... thats logic.... :headbang1:
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paladin just officially made this post completely retarded with his presence.
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its funny cause all of that doesnt matter if you attach the engine of a Harrier jer onto that 747..... cause it would take off straight up...
I
Paladin, Dont make me thrash you too... 747 is much heavier than a Harrier. Would never work.
Cole, that was a high school problem, there was no need to google what was so plainly obvious. hell, even kaneda got it.
So, what are the stakes on this probability problem? I promise not to use the internet... which means, neither can you.
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k w/e, the plane will fly.
More importantly though, who would win in this battle
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WTF??!?? That has to be the most disturbing thing ive seen in here yet. As in, whoever created that probably thought it was cool... a very disturbed 9 yr old girl.
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The Unicorn...I mean...eherm....WHAT IN THE FUCK IS THAT!!!
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lets me a new section in the forum where Kaneda just finds random pictures so i can laugh my ass off
anyone in favor?
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:headbang1:
y'all want a riddle....
Theoretically:
if you were travelling in a car at the speed of light and you turn on your headlights.... what would happen?
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A 9 year old girl.... or someone on some serious drugs w/ a touch of photoshop skills.
As for the car... the light given off by the headlights would never move forward, instead just move along with the car. If you think I'm bull shitting, think again. I've done it. Shits sick.
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to someone sitting in the car, the light from the headlights is travelling at the speed of light forward. To the cop you just passed, the headlight light is travelling 2x the speed of light. Prove me wrong.
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I would try to prove you wrong Dropkick... but then I would just look like Cole
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this one is easy. two things.
However it's very early so maybe i'll post again and figure I'm retarded later. I can be very impulsive in thought.
Nothing can travel faster than the speed of light. Especially something with mass. Also, the special theory of relativity states that the speed of light is the same of all observers.
We don't need to prove this one. Einstien did it for us.
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Flint - you're a trouble maker...the plane flies as long as the bearings in the wheels don't melt before there is enough lift to get the plane airborne.
Although Cobra's smiley is cute - Kaneda's picture made me piss my pants - I vote for Kaneda as having the best reply to this thread!! BTW - those are Mr. Green's second cousins in that pic.
:mrgreen:
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Kaneda should get his own forum...yeah.
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Einstein never watched star trek. If he did, he would have realized that if the enterprise could fire photon torpedos while chasing klingons at warp 9, that you cannot prove me wrong.
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Star Trek is made by a bunch of retards. But I really dug the dolphin pic. It would have been better it it were a rabid sea bass with laser beams on its head instead of the laser tag system the dolphin is wearing.
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Listen, the dolphin is fine, and its not a laser tag system ass hole, its a teleporter. That and his claws are his only defense against the unicorns horn. Thought this was common knowledge....
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I win again!!!!!
I thought it was just a newer model dolphin with the 3rd taillight for extra safety.
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Dude, those are so totally lazer tag IR recievers. Have you ever even played lazer tag? Or photon gun game. And why does the one horn have no bung hole?
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This has clearly become a spam thread. Too bad, I'm going to have to move it into a virtual life of obscurity in the spam section.
Unicorn wins, it has a longer reach... Besides, we all know Dolphins don't have hands...or nubs or whatever you call those thing.
What flavor did Cobra say that clay was? I suddenly feel hungry.
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Now remeber before reading this i am stupid and know absolutely nothing. This is also if you were to ask me and i would ask me.
Cole you are right in that it wont take off but for the wrong reason and the other dudes are wrong
take a stick |
force x ->|<- force y if x=y what the fuck happens. nothing
now add Vibration what happens the stick jumps up and down but stays in the same spot.
but if force x is dropped when it leaves the ground force y is then applied without resistance
so it woul basically skip more and more along the the damn thing until it got high enough you could tilt the thing back to take off.
Now i want you people to realize most planes arnt perfectly balanced and the reason why is they dont need to be under normal circumstances.
Which leads me to my next statement if its moving that fast the front wheel is not going to be held down by anything which means it will tilt
back and smash into the ground if the thrust at that point isnt enough to get it moving through the air. So really it all depends on how much
weight you have in the front of the damn plane. In most cases you wont so guess what the fuck happens boom tail and wings hit the ground.
Now where you goin to go NO WHERE. Thats right where you goin go now NO WHERE. now plz dont get on my nerves by asking stupid
questions. Now this guys may have the degrees he says he does but degrees are worth shit if you dont ever consider the mechanics of wtf you
are workin with. Also if you think about it really isnt flying if its stil touching the ground which creates the whole problem that even if it has thrust
if its moving horizontally porportional to the earth it wont take of it wil just go "flying" down the runway lol. sry had to do a pun
And i was told by my school i dont understand engineering well f them they dont know how to use that thing between their ears.
also rember when you assume u make an ass out of u and me. And when you make an assumption u make an ass out of u pion.
:-D
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Naw MDK22. The thing is, if the belt is moving opposite the plane, the force the belt is transfering to the plane is so small, it wouldn't even be worth measuring. Drag is a force. The connotation of the word "drag" is basically a counteracting force that doesn't stop your movement.
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oh as for speed of light lights speed can be slowed down so technically something can move fater then the speed of light. I am sry someone at some university proved that you can slow down the speed of light so technically something could move faster then it. But ud have to do alot of slowing
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no, you can not slow down the speed of light, however you can hold a photon in a crystal under certain very specific condition. it was a very nice photonics breakthrough which allows for the advent of photonic transistors if you will.
That's different than changing the speed of light...
You are basically trapping photons in a crystal with a very specific crystal structure, then you change the structure and they come out.
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AH so somedbody stated it wrong to me darn i hate people sometimes. As for the plane i still dont understand wtf hes talking about the plane will not be able to go up. Maybe its because im thinking thrust pushes plane forword thus giving the plane speed thus incressing the speed of the convayor. Its not that, that i care about its how are u getting the lift to push it up. Cause u cant tilt the plain back to get lift or u hit the ground.
Maybe u can explain it to me so i feel less dumb. Try and explain it simply so my simple mind can understand.
Also im pretty sure if u are using wheels ur elimanating friction altogether.
Anyway i think we should sumbit it to myth busters cause i want to see what happens cause im pretty sure it would pop a wheely and hit the ground.
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read this. It is good. yum.
http://travel.howstuffworks.com/airplane.htm/printable
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thank you i think i get it cole. :-D