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Posers and Puzzles

Posers and Puzzles

  1. 24 Oct '06 17:51
    Yes, we all now know the airplane does infact fly. My last question is this: would it make a differance if the "treadmill" moved 2 or 3 times faster than the plane. A simple yes or no answer will sufice, assuming its from somebody that actually knew the answer to this question. Thanks
  2. Standard member XanthosNZ
    Cancerous Bus Crash
    24 Oct '06 19:03
    No.
  3. 24 Oct '06 20:19
    no what?
  4. 24 Oct '06 21:00
    which direction is the "tredmill" going in relation to the plain?
  5. 24 Oct '06 21:10
    its going in the opposite direction. Is there a speed of the treadmill that would prevent the plane from taking off?
  6. 24 Oct '06 21:18 / 1 edit
    obvisouly if the treadmill had no maximum speed, because when the plain started rolling down the runway then the treadmill would speed up.

    why wouldent the plain just take off from the taxiway in the first place???

    edit: i mean, after the treadmill started doing that?
  7. Subscriber AThousandYoung
    It's about respect
    24 Oct '06 21:39
    Originally posted by likeforest
    Yes, we all now know the airplane does infact fly. My last question is this: would it make a differance if the "treadmill" moved 2 or 3 times faster than the plane. A simple yes or no answer will sufice, assuming its from somebody that actually knew the answer to this question. Thanks
    Depends if the wheels are considered to have friction or not.
  8. 24 Oct '06 23:25
    yes, obviously the wheels have some friction. thats why my guess is the plane would not take off if the treadmill had a infinitely fast speed
  9. Standard member XanthosNZ
    Cancerous Bus Crash
    25 Oct '06 01:38
    Originally posted by likeforest
    no what?
    No it wouldn't make a difference if the treadmill was going at any finite constant speed. Any discussion of what would happen with infinite speed is pointless as that point all sorts of things happen.
  10. Donation richjohnson
    TANSTAAFL
    25 Oct '06 01:56
    Originally posted by XanthosNZ
    No it wouldn't make a difference if the treadmill was going at any finite constant speed. Any discussion of what would happen with infinite speed is pointless as that point all sorts of things happen.
    At some point the landing gear would snap off or the bearings in the wheels would melt.
  11. Standard member XanthosNZ
    Cancerous Bus Crash
    25 Oct '06 03:33
    Originally posted by richjohnson
    At some point the landing gear would snap off or the bearings in the wheels would melt.
    Not in a thought experiment it won't.
  12. 25 Oct '06 10:30
    How an aeroplane wing (airfoil) creates lift depends on the pressure differential above and below the wing.

    Air flowing over the wing will undergo pressure and speed changes due to the shape of the airfoil, this is because of Bernoulli's principle, which relates the pressure of air to its local velocity. Therfore air flowing across the top of the wing will be at a lower pressure than the air below the wing creating a lift force, increasing the air-velocity will cause this pressure difference to increase, hence increasing the amount of lift.

    So in relating to an aeroplane on a treadmill:

    The aircraft will have zero local speed and therfore zero airflow over the wing and for that reason there is zero lift
  13. 25 Oct '06 11:02 / 2 edits
    Originally posted by XanthosNZ
    Not in a thought experiment it won't.
    XantoZ wrote:
    "Any discussion of what would happen with infinite speed is pointless as that point all sorts of things happen."

    richjohnson answered:
    "At some point the landing gear would snap off or the bearings in the wheels would melt."

    XantoZ says that his last posting was of no value:
    "Not in a thought experiment it won't."

    ...when he should've been saying:
    "Yes, even that could happen."

    ...or perhaps...
    "All points of things but not exactly this."

    ...or rather, as he so very often says:
    "No, because you're an idiot!"

  14. 25 Oct '06 11:10 / 2 edits
    Nevermind

    I get it now, the wheels are free spining, interesting puzzle

    after reading the other thread (some very rightoeus people out there)

    i assume the plane would still take off even if the treadmill accelerated at an equal and opposite rate to the accelerating plane
  15. Standard member XanthosNZ
    Cancerous Bus Crash
    25 Oct '06 12:10
    Originally posted by soulby
    Nevermind

    I get it now, the wheels are free spining, interesting puzzle

    after reading the other thread (some very rightoeus people out there)

    i assume the plane would still take off even if the treadmill accelerated at an equal and opposite rate to the accelerating plane
    "But what if the treadmill continues to accelerate? Different story. In principle it's possible to accelerate the treadmill at a rate that will exactly counteract any forward force you care to apply. (This is a departure from the original question, which said the conveyor belt compensated for the plane's speed,, not its force.) The only mathematics needed to demonstrate this is the well-known physics axiom F = ma--that is, force equals mass times acceleration. Given that the conveyor exerts some backward force F on the plane, we simply crank up the acceleration as much as necessary to equal any forward force F generated by its engines. Result: The plane stands still and doesn't take off."
    http://www.straightdope.com/columns/060303.html