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  1. Join Date
    Jul 2005
    Posts
    199
    #41
    Quote Originally Posted by mbeige View Post
    It's an airplane, not a rocket. Even if it had thrust, it needs lift to take off! Thrust will only push it forward, but what happens here? Negligible yung friction and the conveyor belt instantly brings the velocity to zero dahil yun ang nakalagay sa condition ng tanong.
    the question kasi will lead you to believe na yung conveyor belt is capable of exerting enough frinction on rolling/rotating airplane wheels to stop it from taking off...sabi nga ni niky sa sagot nya..e halos imposible na yun...boy you gonna need trmendous amount of energy to do that..the plane is using its propellers/jet and wings to fly and you are using only friction on its rolling wheels to keep it on the ground?

    airplane, rocket pareho lang yan...the only difference is that an airplane needs to be fuel efficient to be able to travel long distances and carry loads at the same time thus the lower speed and use of runway.

  2. Join Date
    Jul 2006
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    3,601
    #42
    Quote Originally Posted by Alpha_One View Post
    Ah, of course the plane's position does change! The runway is doing absolutely no opposing force. The engine works on the plane, the treadmill works on the wheels. End result, plane moves, eventually it reaches takeoff speed.

    Your statement isn't "proof" because it assumes that the engines are doing absolutely nothing to the plane.
    Ok let's analyze this.

    The plane is sitting on the conveyor belt.

    The conveyor belt pushes the plane and keeps it above the "runway".

    The only point any force from the plane will go to is the wheels.

    The only point any force from the conveyor belt will go to is the wheels.

    If both surfaces are going opposite each other at the same speed, then the plane is not moving.

    The engines keep pushing it against the wind.
    So now there is wind? Akala ko sinabi mo kanina there is no wind?

  3. Join Date
    Dec 2004
    Posts
    1,310
    #43
    Quote Originally Posted by mbeige View Post
    Kaya nga, there is NO wind going opposite in direction. Don't you realize that in order for a plane to take off, it needs lift. Once again you proved my point, since there is NO wind, there will be no lift.

    And with your statement that the runway moves opposite the plane, if both move at opposite directions at the same speed, what happens to the plane? It remains at constant velocity (zero!).

    There is no trick here. It's just simple physics.
    There is a trick here, and it's still within simple physics. But it has absolutely nothing to do with the plane running against the runway!

    Put it this way, you going on the freeway at 100KPH DOES NOT keep cars going the other direction at 100KPH!! The end result is that you pass by each other at 200KPH. It's exactly the same with the plane and the runway.

    Also, I'm curious as to how you came up with the "no wind"/"air not moving" conclusion. Note that it's the ground that's moving against the plane, not the wind.

  4. Join Date
    Jul 2006
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    3,601
    #44
    Quote Originally Posted by nerbyoso View Post
    the question kasi will lead you to believe na yung conveyor belt is capable of exerting enough frinction on rolling/rotating airplane wheels to stop it from taking off...sabi nga ni niky sa sagot nya..e halos imposible na yun...boy you gonna need trmendous amount of energy to do that..the plane is using its propellers/jet and wings to fly and you are using only friction on its rolling wheels to keep it on the ground?

    airplane, rocket pareho lang yan...the only difference is that an airplane needs to be fuel efficient to be able to travel long distances and carry loads at the same time thus the lower speed and use of runway.
    Dude, that was the original condition. Are you telling me that Alpha and Niky are talking about realistic worlds, while I am basing my answer on the question? Then I guess that's the only thing that makes sense!

    Whether it is impossible or not, that was the given. And I am sticking with that.

    the plane is using its propellers/jet and wings to fly and you are using only friction on its rolling wheels to keep it on the ground?
    Ain't that the truth! The only difference between reality and this is that the runway is stationary and will NOT match the plane's speed in the opposite direction.

    airplane, rocket pareho lang yan
    Tell me, how does each one take off the ground? The plane uses Bernoulli's principle which states that the lower pressure above the wings will generate lift because the higher pressure below the wings will push it up (remember, pressure goes from high to low).

    A rocket takes off using sheer thrust. The fins are just used to stabilize it and guide it along, NOT to generate lift. Otherwise, it would have been called a plane.

  5. Join Date
    Jul 2005
    Posts
    199
    #45
    sir, nakakita ka na ba ng trick na hinila yung table cloth pero yung mga pingan at yung baso hindi gumalaw sa ibawbaw ng table? for all we know, the speed of the conveyor may even make the non-running airplane stay in place because of weight and gravity...then add power to the plane...zoom it goes.

  6. Join Date
    Aug 2004
    Posts
    22,710
    #46
    No. The force from the engines goes to the plane in total.

    The only given is that both surfaces are moving at the same speed, in opposite directions.

    To reiterate my last post, to exert enough force on the plane to keep it stationary, the belt must be moving faster than the plane.

    Again, this is based on the question, only, no other conditions given.

    If the plane were driven by its wheels, it will remain stationary. But it's not. That's all.
    Last edited by niky; November 9th, 2006 at 07:45 PM.

    Ang pagbalik ng comeback...

  7. Join Date
    Dec 2004
    Posts
    1,310
    #47
    Quote Originally Posted by mbeige View Post
    Ok let's analyze this.

    The plane is sitting on the conveyor belt.

    The conveyor belt pushes the plane and keeps it above the "runway".

    The only point any force from the plane will go to is the wheels.

    The only point any force from the conveyor belt will go to is the wheels.

    If both surfaces are going opposite each other at the same speed, then the plane is not moving.



    So now there is wind? Akala ko sinabi mo kanina there is no wind?
    You're wrong in assuming that the plane's "force" goes to the wheels. The plane doesn't make any force, it gets its force from the thrust from engines. The wheels gets all its force from the conveyor belt.

    The plane moves at 1MPH. The conveyor belt moves at 1MPH in the opposite direction. The plane gets a 1MPH wind across it's wings (clarify ko na ha!), the wheels just spin. Eventually the plane gets enough "wind" on its wings to take off and takes off.


    When I said there is no wind, I meant that the wind isn't going to change it's velocity when the plane does. Planes take off perfectly fine in the real world without "wind". The engines push the plane forward and makes it's own "wind" on the wings. Your statement(s) is(are) completely fallacious in concluding that there cannot be wind against the plane.

  8. Join Date
    Oct 2002
    Posts
    19,438
    #48
    Quote Originally Posted by Alpha_One View Post
    There is a trick here, and it's still within simple physics. But it has absolutely nothing to do with the plane running against the runway!

    Put it this way, you going on the freeway at 100KPH DOES NOT keep cars going the other direction at 100KPH!! The end result is that you pass by each other at 200KPH. It's exactly the same with the plane and the runway.

    Also, I'm curious as to how you came up with the "no wind"/"air not moving" conclusion. Note that it's the ground that's moving against the plane, not the wind.
    sir, the airplane is stationary with respect to it's environment because of the conveyor under its wheels. now where does the wind come from?

  9. Join Date
    Jul 2006
    Posts
    3,601
    #49
    Quote Originally Posted by Alpha_One View Post
    There is a trick here, and it's still within simple physics. But it has absolutely nothing to do with the plane running against the runway!

    Put it this way, you going on the freeway at 100KPH DOES NOT keep cars going the other direction at 100KPH!! The end result is that you pass by each other at 200KPH. It's exactly the same with the plane and the runway.

    Also, I'm curious as to how you came up with the "no wind"/"air not moving" conclusion. Note that it's the ground that's moving against the plane, not the wind.
    This is my last reply for the night, it's 3AM and I'm supposed to be in bed.

    Your freeway analogy is NOT the same. Why? Because the cars are already moving, but in this case you're starting with a NON-moving body to be compared with a NON-moving body.

    The ground is not moving against the plane in the real world, the plane moves against the ground. I did not say that the ground is moving against the wind! Where did you get that bit?

  10. Join Date
    Oct 2002
    Posts
    19,438
    #50
    A plane is standing on a runway that can move (like a giant conveyor
    belt). 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) instantly.
    again and again, whatever force the wheels or the jet engines of the plane produce is negated by the conveyor that keeps the airplane stationary. you cannot produce any lift with a stationary object.

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Will the Airplane Fly??????????