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Position of the helicopter

  1. Sep 4, 2012 #1
    Suppose a helicopter is stationary at certain height And a observer sees it from ground. But after one day the observer again sees the stationary helicopter than will it appear To be at the same Position Or somewhere else
     
  2. jcsd
  3. Sep 4, 2012 #2

    CWatters

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    You need to define what "stationary" means. Nothing is every really stationary...it's all moving around he sun, the sun moves around the galaxy etc..

    If you tell the pilot to remain stationary above a point on the earth he will still be there the next day. If you tell him to remain stationary with respect to the sun he won't still be there (or even on the planet if his helicopter worked in space!).
     
  4. Sep 4, 2012 #3
    Just consider the helicopter To be an automatic machine And just standing on the height without any movement. Will the Position be affected by rotation of earth on Its axis.
     
  5. Sep 4, 2012 #4

    CWatters

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  6. Sep 4, 2012 #5
    Well that helped but the two Are different things And What i interpreted from the article means the Position will change but will it appear To the observer changed as he also rotates with earth
     
  7. Sep 4, 2012 #6

    CWatters

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    If we ignore problems with the way the question is set then yes the helicopter might remain fixed while the earth rotates below it. Much as the moon remains facing the earth as the earth rotates below it.

    PS It really does matter how the question is set. In practice a helicopter can't remain at a constant height without the rotor remaining roughly parallel to the earth surface.
     
    Last edited: Sep 4, 2012
  8. Sep 4, 2012 #7

    CWatters

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    Remember that the helicopter and atmosphere of the planet rotate with the planet. A helicopter won't be "left behind" when it takes off. It will continue to rotate with the earth.

    The more interesting question is this.. Does the rotor act like a gyroscope and try to keep the plane of rotation constant leading to the helicopter "falling over".
     
  9. Sep 4, 2012 #8

    russ_watters

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    Does the atmosphere get "left behind" by a rotating earth?
     
  10. Sep 4, 2012 #9
    You can try this.
    Inside a moving train, throw a ball vertically and without moving the postion of hand, will it drop at the same position as it left your hand.

    If return to same point, then you must ask what make it follows you?
    Once it tossed up, it left your hand and the train and not connected with anything.
    It is all about vectors.
     
  11. Sep 4, 2012 #10

    mfb

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    Without movement relative to what?
    Relative to the floor? In this case, it will stay at its apparent position for observers on the floor - by definition.
    Relative to the center of earth, in non-rotating coordinates? This would look like a helicopter flying with some hundred kilometers per hour (depending on the latitude) towards west.
    Relative to the sun, in non-rotating coordinates? In this case, the helicopter would travel with ~30km/s relative to the floor, where the direction depends on the time of day (should be "down" at sunrise, "east" at noon, "up" at sunset and "west" at midnight).
    Relative to the galaxy, in non-rotating coordinates? The helicopter would travel with ~220km/s in some direction, which depends on the time of day and the season.
     
  12. Sep 5, 2012 #11
    Thank you all
     
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