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Physics question: Can the plane take off?

straightdope.com — A plane is standing on a runway that is made of a large conveyor belt. The plane fires up its engines, but as it moves forward, the conveyor belt senses the speed of the plane's wheels and moves at exactly the same speed in the opposite direction. Can the plane take off?

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  • archerx, on 10/22/2007, -29/+22If no air goes under the wings to produce lift then no.
    • achille, on 10/12/2007, -13/+16The puzzle never mentions anything about "air". You have a plane being propelled forward by an engine, and you have a runway moving at the same speed as the plane. The wheels will spin twice as fast, but the plane picks up speed and then takes off. C%u2019mon, look harder at this.
    • shrewd, on 10/12/2007, -15/+21the lift is produced by the pressure difference created by the rapidly moving air over the wings, nothing else.... so without the rapidly moving air... ZERO and i mean this: ZERO takeoff... it's not going to happen, not only that but the plain actually has no momentum, so what's it going to do make a verticle takeoff?

      only if it was a plane that was cabable of making a verticle takeoff...

      the trick with this question is that the conveyer belt isn't actually counteracting the forward momentum of the plane, it's simply spinning the wheels while the jets push it forward.....
    • Greg-J, on 10/12/2007, -18/+54.

      PLEASE READ

      After reading this entire thread, it's apparent that quite a few people are pretty clueless.

      Aircraft do not derive their forward thrust at their wheels. If a plane is traveling at 250mph on a conveyor belt, and the conveyor belt is moving at 250mph in the opposite direction, the aircraft is still moving at 250mph. The wheels are spinning at 500mph. That's the only difference.

      The friction caused by the wheels touching the conveyor belt isn't nearly significant enough to slow the craft down whatsoever.

      But to those of you insistent that somehow the conveyor belt will magically remove the forward thrust coming from the propellers/jets, please see this link --> http://www.prntscrn.net/img.php?img=heres-your-sign.jpg
      .
    • Olle, on 10/12/2007, -11/+2Now, I haven't been able to read the article, so if the article indeed states that the plane will take off then I don't understand how.

      The premise is that the conveyor belt will turn at the same rate as the wheels. For the plane to more forward the wheels have to spin faster than the conveyor belt.

      People say that the friction of the wheels is less than the pull of the propellers. And that is normally true.

      But with this premise the wheels would spin faster and faster until the friction evens out. So, the conveyor belt might spin at a speed of 10 000 mph (or something). And at that speed or some other speed the friction of the wheels will equal the push of the propellers.

      Well, that's my thinking. Wish I could read the article.
    • tedfa, on 10/12/2007, -8/+4it will take off.
    • lollerskates, on 10/12/2007, -5/+2These folks are correct. The plane will take off. It's not a physics question so much as it is a logical question.
    • savmac, on 10/12/2007, -0/+1and don't call me Shirley!
  • Meowmix, on 10/12/2007, -6/+6Haha, cool. So simple, yet so confusing.
    The straight dope is awesome.
  • cjcd, on 10/22/2007, -31/+6no air, no lift, no takeoff.
    • KSUdesigner, on 10/12/2007, -6/+20Read the article next time, you will see that it does indeed take off.
    • caraiancaldazar, on 10/12/2007, -5/+2ya, but there is air
  • Floodle, on 10/22/2007, -6/+37yes it does, planes are not powered through their wheels like cars are, the engine fires up and blasts the plane forward, the conveyor belt spins in the opposite direction making the wheels spin at 500 mph when the plane is only travelling forward at 250 mph. The plane still takes off because it doesn't matter what the wheels are doing, they are simply spinning on their bearings.
    • dggeek, on 10/12/2007, -9/+7^^

      Took me a couple minutes to figure this out, but yes, this is the correct answer.
    • linnerd40, on 10/12/2007, -7/+1Good point!!!
    • rbenech, on 10/12/2007, -0/+1The plane WOULD be travelling at 250 mph if the conveyor belt was going 500 mph. (that would be a killer word problem) But, the plane would be traveling forward despite any effort the conveyor belt has on the weels (- friction of course). If the plane was really a glider and needed something to pull or push it to get off the ground (like a truck), the truck would never be able to overcome the "pull" of the conveyor belt and would not be able to pull the glider... But a plane does not achieve speed by forcing it's wheels to spin, it gets it's speed from pulling/pushing air... (and why conventional propeller aircraft wouldn't work in space)
    • blitzman, on 10/12/2007, -4/+8A jetliner normally takes off at about 160 mph. The conveyer would then be spinning the wheels at double the normal speed, or 320 mph. The jetliner won't take off because the tires will explode before it gets to that speed. If the pilot continued to gun the engines, a large fireball would be created as the undercarriage ground against the conveyer belt, or the pilot would lose directional control due to the uneven drag and it'll crash.
    • rockintom99, on 10/12/2007, -1/+5Heh, yeah, at first i was totally at the assumption that it wouldnt take off, but then its really just a trick question. I DID smack my forehead, in the same way the article said. Good riddle.
  • TheFightForGood, on 10/12/2007, -24/+8definately wouldn't take off. it's not the thrust that makes the plane fly, its 100% lift. the thrust just gets the plane moving forward to create lift. if you remove that forward motion there is no longer lift, thus there is no flying, just moving wheels.
    • scuba7183, on 10/12/2007, -22/+8agree with that guy ^. with movement, there is no lift, without lift, there is no flight.
    • KSUdesigner, on 10/12/2007, -7/+11You people need to read the article first.
    • zybch, on 10/12/2007, -5/+7Its amazing that so many people are so stupid :)
      The only difference between this situation and a 'normal' take off is that the wheels are spinning at the rate of 500mph. The plane is STILL moving forward at 250mph, enough to provide the neccessary lift to get airborne. The wheels provide NO momentum at all!
  • Comfuser, on 10/12/2007, -4/+7it would take off. just think physics, F=m*a. The forward force (from the thrust) in both case is always bigger than the backward force (due to the friction of the wheel and ground, and it's very small compare to the thrust force), therefore the net force is always forward. So the plane will accelerate forward in both cases and take off.
    • scuba7183, on 10/12/2007, -15/+6uhhh....force has nothing to do with this. it's about the speed of the air over the curvature of the wings and the aerodynamics that creates lift and would propel the airplane upward.

      wow...that sounded really smart. here's to a 95 in science
    • dawgma, on 10/12/2007, -2/+8Actually, it is all about the force - the force of the jet engines.

      Regardless of how fast the conveyor is moving, and since the plane is not powered by its wheels, the plane will move forward proportional to the force of its engines. The wheels will spin as fast as the forward motion of the plane PLUS the speed of the converyor belt. All the converyor belt does is spin the wheels faster, without hindering the forward motion.

      Don't worry Scuba, the answer must have been part of that small 5% of science you never could figure out. Ya. ;D
    • GhengisKhan, on 10/12/2007, -1/+1Yes, it would, The force is generated by a separate entity, the engines, not by the 'countered' wheels. The plane engines FORCE the MASS of the plane, causing ACCELERATION.
  • Lord_oftheTrons, on 10/12/2007, -2/+6Pretty cool and awkward problem. It would definitely still take off though. Unless you increased the friction in the wheels/bearings to a ridiculous amount, this thing would still get off the ground.
  • willhaney, on 10/12/2007, -2/+2"The plane moves in one direction" As the plane reaches it’s takeoff velocity x, the wheels would be spinning at 2x being that “speed of the conveyer to be exactly the same (but in the opposite direction).” The plane would take off in this version of the question.

    However, in this version, the plane will not take off.
    http://www.rcgroups.com/forums/showthread.php?t=446465
    Still, in the poll, there were 159 members who voted it would take off while 192 voted it would not.

    Will
    • mikeyG9x, on 10/12/2007, -0/+0The only difference is that your problem includes "no wind". In this problem, the aircraft is not going to care about "wind". The only thing the conveyor belt will do is spin the wheels faster (in both problems).

      The aircraft will take off (both versions).
  • geminitojanus, on 10/12/2007, -5/+11Sounds like a job for the Mythbusters. Go buy an old Boeing jet that's still flightworthy, build a "kite-rig" for it, build a gigantic conveyor belt, and let's try this out.
  • achille, on 10/12/2007, -4/+13I hope the people who commented above me have misread the question. Of course the plane would fly. A plane does not get it's airspeed from its wheels. If the plane is going "forward" at 200 Mph and the conveyer is going back 200Mph, then the wheels would be "spinning" at 400 mph.(*) But the plane is "still going forward!

    Well, technically the wheels would be spinning at the same RPM they would if they were going 400 mph
    • Techeon, on 10/12/2007, -2/+4This all has nothing to do with the wheels. It all has to do with relative wind. The airplane is staying in the exact same spot until it is able to leave the ground (conveyor belt). There is no relative wind. It can not fly. The engines provide zero lifting force. The only reason airplanes have engines is to provide a forward motion to generate relative wind so that the air moves faster over the wing to create a lower pressure.

      Its kinda like the principle of aircraft carriers. Planes are slingshot off of the platform to provide forward motion. Why? Only to generate relative wind in a shorter amount of distance.

      Its like if you were running on a treadmill. You feel no wind against your face because you are not moving forward. Where as if you were running down the street you feel wind (relative wind [relative because of your forward motion through the air]).
  • 2ltkap, on 10/12/2007, -13/+2no air movement over the wing surfaces no lift no flying ....no problem
  • jwolf, on 10/12/2007, -2/+8It absolutely can.

    Because the plane relies on its engine to produce thrust which propels the plane forward, the speed of the wheels is irrelevant. Because the wheels are freewheeling and not transferring power to the ground (like a car or motorcycle), aside from the negligible amount of friction they produce do not really factor into the equation.

    Assuming the fictional rolling runway is long enough for the airplane to take off, it will.


    • Dano18, on 10/12/2007, -5/+0Cecil's explanation of point #2 is off however. he says that the plane would move backwards when the treadmill accelerates "because the treadmill is accelerating the rollerblade wheels and in the process imparting some angular (rotary) but some linear (backward) momentum to them." But the wheels cancel out the "linear" momentum, because as the bottoms of the wheels accelerate backwards, the tops accelerate forwards. The reason you're initialy tugged backwards is because there is friction in the bearings, and more importantly their is a surface adhesion/friction between the rubber wheels and the rubber track, this is overcome by inertia but not before initially accelerating the plane (or rollerblades) backwards. And yes, as others have said the plane would take off because the wheels are free spinning. Airplane wheels do not even have brakes.
  • jonesin, on 10/12/2007, -7/+2I sure as hell don't know the answer, but man, what an awesome question.
  • machinelou, on 10/12/2007, -4/+8I can't believe anyone spends any time thinking about this question. The wheels on an airplane have no effect on speed caused by jet engines. Therefore, the plane will roll in the opposite direction of thrust (newton's law of motion) unless it has some serious wheel bearing problems (too much friction). The plane will more forward independent of some kind of super conveyor belt moving in the opposite direction. When the plane gets moving fast enough relative to the on coming air speed, the plane will lift off the ground. Again, this is independent of the planes speed relative to the ground. The plane only needs speed relative to the air. Ever seen pictures of a wind tunnel before?
    • mentor, on 10/12/2007, -1/+2Indeed, it is only the speed of the plane relative to the air around it that determines the lift of the wing. It is perfectly possible to fly into the wind, generate lift, but still be going backwards; if the wind is going faster than you are.
      So here's a thought experiment. The wheels don't matter, so if they're not mving it won't change anything. So what happens if we put brakes on the wheels so they can't move at all at the thrust levels of the plane. Will it still take off?
    • lfrandom, on 10/12/2007, -2/+1Well, it would certainly mess with the tires.
    • giloron, on 10/12/2007, -0/+1All depends on how much air the engines can move. I doubt any current plane is designed to do that, but I'm sure we could do it if we wanted to.
    • mentor, on 10/12/2007, -0/+1Doh. I get it now.
      The engines produce thrust relative to the air. If the aircraft was standing still on the runway, of course it won't take off; but it's not standing still on the runway because the engines don't care about the runway either.

      The only factor that would affect this would be the friction of rolling in the wheels. I should imagine the force generated from this is proportional to speed, but a steady state solution wouldn't occur before the tyres exploded.
  • iwantansi, on 10/12/2007, -10/+6so while its on the conveyor belt basically not going anywhere, its just going to magically lift off the ground with no air going over/under the wings... think about it... if it would fly, wouldnt the armed forces use this on aircraft carriers?... theres no air... no lift
    • anamexis, on 10/12/2007, -1/+2Dude, read any of the above 20 or so comments explaining why you are wrong.
  • robbh66, on 10/12/2007, -4/+5Somone call the myth busters. I want to see a little RC plane on a conveyor belt.
    ...
    Strike that.
    ...
    I want to see a small 2 seater on a big ass conveyor belt.
  • dmitri926, on 10/12/2007, -7/+4Thrust or not, the plane flies due to low pressure on top of the wing and high pressure bellow the wing.. if the plane is standing still and there's no air moving through the wings then the plane won't fly because there'll be no pressure differences.

    Who's with me?
    • ScoTTeh, on 10/12/2007, -1/+2The thrust comes from the engines which unlike a car arnt attached to the wheels. The thing is that the plane will move because the force against the wheels (the belt) doesnt really matter.
    • Quaitemp, on 10/12/2007, -0/+0The jets are applying force on the air, not on the ground, so the movement of the plane will be relative to the air around the aircraft, not the movement of the ground.

      (No, English is not my native language..)
  • ryandbrimhall, on 10/12/2007, -7/+4Why is everyone talking about the speed of the wheels? That doesn't have anything to do with it. My instincts say that since there is no air movement there would be no lift created. Is that an incorrect notion?
    • temfate, on 10/12/2007, -0/+0Yes, you are incorrect. The plane moves forward do to it's engines THRUSTING air out the back of them. Is does not matter that the wheels being pulled backwards by a track. The engines still accelerate the air around them, and thus the plane. The wheels are simply going to track faster.
    • giloron, on 10/12/2007, -0/+1To put it another way, the conveyor would have to go extremely fast for the resistance in the barrings to equal the force of the engines.
  • darkone_05, on 10/12/2007, -3/+3Any grade school-er could see the answer to this. Of course it can take off, the wheels have nothing to do with it. The conveyor belt wouldn't alter the airflow. Thrusters push air which pushes plane forward (through air). At the point when the plane is moving fast enough (through air) lift will be produced by air moving over the curved wing. Nothing to do with the ground or wheels. Why do you think a Harrier just can take off from hover?
  • Flipperbw, on 10/12/2007, -2/+7All the NO people are saying is:
    "No lift = no flight"

    All the YES people are saying is:
    "The wheels just spin"


    How about we address each other's responses? I have no idea myself, and the site is duggeffect.
  • ctheory, on 10/12/2007, -4/+2Haha, that's a cool read.
  • gregm, on 10/12/2007, -3/+4Things like "no air movement over the wing surfaces no lift no flying ....no problem" are poor responses because you obviously did not stop to think.

    The plane WILL FLY because the engines (assuming their jet engines or propellers) will propel it forward. The wheels simply hold the plane off of the ground. The plane will move forward. It will then take off because it has forward movement and therefore lift!

    The only factor in this debate is whether or not the wheels are driving the plane. If they are, then the above statement is, infact, correct.

    The site is dead... :( So I don't know what it said about this, but I am simply using my logic to answer the question.
    • KSUdesigner, on 10/12/2007, -4/+2Site works for me. The plane will indeed fly, but the engines don't propel it forward, they PULL it through the air. I think the better question is...if the conveyor belt is going the same speed in the opposite direction, the wheels are moving twice as fast, are the wheels strong enough to withstand those forces before the plane is able to get off the ground?
  • sp1nm0nkey, on 10/12/2007, -3/+4It'd take off, or it'd nose over and crash. Depends on how fast the plane has to be going to take off.

    The connection between the plane and the conveyor is the wheels, which are on bearings, so short of the bearings failing (which could happen if the max speed of the bearings is exceeded), there's nothing that'd keep the plane from taking off.
  • HeyBob, on 10/12/2007, -7/+4Do you feel wind in your face when running on a treadmill? Of course not. Wings need air to flow over them to create lift . If the plane is not moving through the AIR, it's not going to fly through the air. (didn't read the article, just used my gnoggin)
    • Brennan, on 10/12/2007, -1/+3So if someone pushed you while you were running on the treadmill you wouldn't fall off or move or anything?
    • kmoz, on 10/12/2007, -0/+0No, you wouldn't fall off, assuming your feet were wheels in a stable tripod configuration, and the conveyor compensated for your sudden 'forward' force by increasing the backwards force on said wheels. Just as the conveyor in the original question does.
  • spikes, on 10/12/2007, -6/+3Yeah, I'm surprised of all the people here who believe that the air that surrounds the plane will move along with the belt as well. Just plain incredible. the plane has to have air blowing across its wings to create lift, unless you're in a damn wind tunnel this ain't going to magically happen for you.
  • xile, on 10/12/2007, -1/+9You guys crack me up. Jet airplanes fly by pushing air through their engines. This process is not impeded in any way by the conveyor belt because the wheels are not powered.

    As a quick follow-up--why would the owner of a small plane tie it to the tarmac (assuming he/she was parked on a tarmac) when finished flying? The wind can blow the plane, cause lift, and flip it. The wheels didn't turn, but lift was created.
    • mexter, on 10/12/2007, -1/+2Umm, not quite. The engines provide forward momentum. The wings provide lift. However, since the air around the wings is (for all intents and purposes) stationary, there will be no lift and therefore no flight.
  • IKbot, on 10/12/2007, -3/+4YES!

    The wheels, designed for minimum friction, just spin faster. The forward force comes from the engines, not the spinning wheels.
  • pintong, on 10/12/2007, -2/+5Short answer:
    If it was a car with wings, it couldn't because the treadmill would kill any speed it tried to gain.

    If it is a plane, the thrusters will propel the plane foreward and the wheels spin with no help to the plane.
  • linnerd40, on 10/12/2007, -1/+1Ahh... the simple joy of thinking about a problem you perceive as difficult and then hitting yourself with a book when you notice the sheer simplicity of it all. This really was a problem for the geeks. Personally I found it quite understandable after a few minutes of contemplation, but for a non-geek, it could provoke some serious *gasp* thought! : )
  • ShaneApex, on 10/12/2007, -6/+3What about a plane with pontoons? Think about it, the plan is moving forward because of the propeller pulling it forward. The wheels are there as a means to move the plane easily over the ground. Woopy ding, doesn't deserve to be on the front page, no digg.
  • Qubous, on 10/12/2007, -6/+4Is it possible to run up the down escalator? Of course!
  • jackspack, on 10/12/2007, -11/+2FOr those saying this has nothing to do with the wheels and the plane WILL take off - guess what - when the engines are fired up and the brakes on the wheels are on, does the plane take off?

    The engines produce thrust. Thrust produces motion. Motion prodcues the opposite physical forces, in this case, air on the solid object (the plane). Obviously when the lift is greater than the drag, you are airborne.

    If the forces that help created greater lift over drag are ***** with, you get no lift. ***** with being - the brakea are on, there is a big honkin' pice of wood in front of the entire plane causing a draft around the plane, or the plane is sitting on a conveyer belt and the thrust which cause motion which causes the wheels to spin but the force at which is acting upon the plane (the conveyer belt) is not allowing the motion of air to flow around the airfoil causing lift.

    No lift. No digg.
    • Dano18, on 10/12/2007, -6/+0Jackspack- planes don't have brakes on their wheels, and lift does not have to overcome drag, but gravity. Engine thrust force has to overcome drag in order for the plane to move forward.
    • KSUdesigner, on 10/12/2007, -0/+2Your argument about the brakes is completely invalid. Without the brakes on, the plane has little friction with the wheels because they ride on bearings. When the brakes are applied, the friction is great enough that the plane remains stationary. Click the link to "the straight dope" in the article and it may clear things up for you.
  • StigT, on 10/12/2007, -2/+3In a car the wheels push the car forward. In a propeller plane the propellers pull the plane forward, in a jet plane the jets push the plane forward. doesn't matter what the wheels are doing on a plane, the engines will move the plane, causing air movement over the wings, causing lift.

    For those of you that think the plane will not take off answer this question:
    Why does the plane move forward once it is in the air? The wheels sure aren't doing anything then.
  • darkpath, on 10/12/2007, -2/+5Since the site seems to be dugg to death (at least for me), I'll throw out my take on it off of just what was said in the Digg plug of it.

    I think the key here is the phrase "as [the plane] moves forward." Most people arguing that the plane would not take off seem to be saying that it's because there's no movement of air over the wings... this seems like an assumption that the plane is STATIONARY, which, unless I'm reading this wrong, the plane is not. As the plane MOVES forward, the only thing that changes is the speed of the runway moving backward. This is not canceling out the forward movement of the plane... more friction than just the wheels generate by spinning would be needed... much more, I think.

    So to sum up: The plane would take off because, while the runway is moving opposite of the plane, the plane still moves forward and thus gains lift due to the air moving over the wings.
  • kev01, on 10/12/2007, -3/+6I thought this question made the internet msg board rounds years ago...

    ANSWER:

    YES THE PLANE TAKES OFF

    Think of an analigous situation, where you have a jet pack strapped to your back and you are standing on a SKATEBOARD.

    You are standing on this skateboard which is on this magic runway.

    Fire on your jetpack.

    $10 says you MOVE FORWARD.
  • Godric, on 10/12/2007, -9/+3If the plane is stationery relative to the ground, then there is no air flowing around the wings. Therefore, no lift. Therefore, no flight.
  • MindReaver, on 10/12/2007, -8/+2How can the plane take off, if there is no lift. It may be producing enough force, but it needs air (Bernoulli 101) moving past the wings. If the plane maintains a stable position relative to something next to it, how can it take off.

    Yes, I read the article, and I still disagree. Mythbusters, anyone. Don't need a Boeing, a small R/C plane will do.
  • kevbryant, on 10/12/2007, -1/+4take it in the converse..if i was falling, but the ground was always moving away from me, would i be considered as floating? of course not. this doesn't take much science, just common sense. flight is caused by air being moved around the wings,, if you were blowing intense amounts of air, say from a ridiculously huge fan in front of the plane, then yes this would work, but of course, the ground would have little to do with it.
    • mexter, on 10/12/2007, -0/+1Of course you wouldn't be falling; you'd be burning up!
  • cranium, on 10/12/2007, -1/+5Of course it will take off.

    The planes wheels free-spin, they don't provide acceleration in either direction. The only important force is the thrust of the engines.

    Since f=ma, f being the thrust, m being the mass of the plane, acceleration will be essentially the same as before.
  • Brak710101, on 10/12/2007, -13/+1No air pressure changes, no lift. If the air was moving and not the plane, the plane could take off (wanted to or not, lol). But moving the wheels and not moving the plane does not change that all important life under the wings from the air pressure. This person should not have graduated, at least in physics.
  • devoinregress, on 10/12/2007, -1/+5The wheels do nothing but reduce the friction between what the plane rests on and the plane. Te ground speed has absolutely nothing to do with the speed of the plain. If the plane were a car then it would get nowhere but the friction against the ground is insignificant.

    if the ground moved under an airplane that was in the air what would happen?
  • JustinZ, on 10/12/2007, -13/+2you retards need to understand the principals of flight


    NO it wont take off, i cant belive this is even a question
  • HappyManEd, on 10/12/2007, -4/+1I would think that the plane would have plenty of thrust, but no movement if it is on something that just makes the wheels spin. And if it is not moving forward, their would be not lift under the wings. So I would answer no to it taking off. The page did not load for me, so I am sorry if I missed something.
  • darkone_05, on 10/12/2007, -2/+4READ BEFORE POSTING:
    Conveyor belt moves backwards, but plane still moves forwards because engines push AIR, not GROUND. It doesnt matter if the belt were moving 10000000000 mph backwards(except for bearings), the wheels are free turning, just like on a match box car. The plane moves forwards from pushing air back, so it will still move forwards and still fly. Once again, think of a Harrier jet, no ground at all. Ground is negligible.
    • HeyBob, on 10/12/2007, -0/+1Harriers are not regular airplanes - they can direct their thrust directly down, overcoming gravity (like a rocket), then they slowly change the thrust pitch aft, to send the plane forward. At some point lift from the wings takes overand it actually starts flying.
    • temfate, on 10/12/2007, -1/+0While you have a good point, at that speed the bearings in the wheels would lock up or seize/melt and there would become a LOT more friction... Maybe I realistic number like 50,000 mph?
  • spikes, on 10/12/2007, -2/+1This is no different then the shooting of a gun on a highspeed maglev train. If the train is going forward and the bullet is shot out from the rear of the train at the same speed as the train moving forward, the people on the ground by the track is just going to watch the bullet drop to the ground.
    • RFRStormer, on 10/12/2007, -0/+1Actually , The gun once fired is 1 ms of thrust. While a jet engine will give continuous thrust (until you have run out of fuel). So your example will not work in this case. If you fired a missile out the back of the Maglev Train, even if the initial velocity was the same, due the fact that the missile has a longer period of thrust the viewers would see the missile move forward.

  • mdshort, on 10/12/2007, -3/+3The plane would move forward anyways because the plan is being propelled by the engines and not the wheels, they will just spin.
  • orangekid13, on 10/12/2007, -4/+3i hate how many people are sooooo retarded to think that a jet engine somehow powers the wheels of the plane... how would it keep going in the air you *****!??! lets replace the ground ice and the wheels with skis... it doesn't matter.
    the air will still go through the engines, combine with fuel and spark to make fire to turn the fans that pushes the plane. as the plane gets pushed, air flows over and under the wings (specifically it moves over the wing faster) to make lift. the airplane takes off.
  • muikano, on 10/12/2007, -6/+2I've always thought that the difference between pressure was what made airplanes fly. Like a propellor for a boat. It causes a vaccuum (Lowpressure) behind the boat, which then is filled by the high pressure on the sides of the boat. That's why the boat bobs up and down, and goes forward.

    When an aiprlane is cutting through space, it's violently disrupting the airflow by the shape of it's body. The different shape of the wings. The bottom is convex and the top is flat, causes different pressure. By turning the fins on the wing, you control the pressure and thereby flight.

    If your staying in place, your not cutting into anything. There's no flight.
    • erikt311, on 10/12/2007, -0/+0True. But you aren't staying in place.
  • gregm, on 10/12/2007, -2/+6THE PLANE IS PUSHING AGAINST THE AIR PEOPLE. THE WHEELS JUST HOLD IT UP!

    Now, if the wheels are stuck to the treadmill, then ofcourse it's not going to take off. However, if they are free to roll, IT WILL take off!

    The plane pushes against the air to provide its forward momentum. It doesnt use the ground except in landing to slow down. Even if the brakes are on, a plane can take off if it has enough power!
  • senectus, on 10/12/2007, -4/+1Of course it WILL take off, what they didn't tell you is that the wind was blowing at over 300 km/hr that day ;-)
    Plenty of lift..
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