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Thread: Your random thoughts of today

  1. #101
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    Very bad mood
    There are days .. so and so ... Damn ... Normal .. and also Fantastic Days ... it is life

  2. #102
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    Quote Originally Posted by AdHoc View Post
    Around the Equator, with:

    d1 (Earth Mean Radius) = 6.371.000 meters
    d2 (d1 + X-15 elevation) = 6.402.100 meters
    P1 (Earth Circumference) = 40.075.017 meters

    P2 (Trajectory Perimeter) = 2πd2 = 40.225.580 meters

    40.225.580 ÷ 7.274.000 = 5.53 hours

    ... or ~5 hours 31 minutes 41 seconds
    what does this number stand for 7.274.000? there's two options to fly around the planet, you can fly eastwards or westwards. the eastern way will take longer because of the rotation of the planet.

  3. #103
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    The 7,274 was the speed in km/h

    The method AdHoc used was for a sidereal orbit, which is literally the time taken to fly through an angular distance of 2 pi radians. To reach the same position over the Earth's surface again, a synodic orbit, you would need to account for the rotation of Earth and you would need to work out how far the plane would need to travel before it has a phase difference of 2 pi radians with Earth.

  4. #104
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    The round form of the earth is kinda like a differential, considering rotation speeds at different points.
    Or 2 hours half-sleep are not enough for me... xD

  5. #105
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    Earth does not undergo differential rotation. Its linear rotational speed does vary depending on your latitude, but its angular speed is constant. Differential rotation happens in fluids.

    In actual fact, what am I talking about? Earth's rotation is irrelevant here! The example I gave above was from a purely mechanical point of view, assuming both bodies were being observed from an external frame of reference and the plane was moving completely independently of Earth. It's not, the plane is taking off from Earth, and so to the plane Earth might as well not be moving. The speed of the plane is relative to Earth, so the time for it to circumnavigate is simply what AdHoc said. Earth's rotation doesn't even enter into it.

  6. #106
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    Huh, oh I was just "Ontopic" with a "random thought"

  7. #107
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    That's just the teacher in me jumping out

  8. #108
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    And for me just the petrolhead. ^^

  9. #109
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    Quote Originally Posted by Hellfire_WZ View Post
    you would need to account for the rotation of Earth
    Ouch

    Well, if the plane was flying much higher, maybe... But you corrected it quickly anyway

  10. #110
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    All I did was driven by the intention to convince her being with me.
    Now I do it just to make her happy.
    Last edited by Jonny; 15th July 2015 at 07:08 AM.

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