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Homework Help: Airplane around the equator

  1. Oct 25, 2007 #1
    1. A)How fast and in what direction would an airplane need to fly(relatively close to the ground) around the equator to always stay in sunlight or darkness?
    B) How fast and in what direction would an airplane need to fly at 40 degrees North Latitude to always stay in sunlight or darkness?

    Im having trouble figuring out what equation would be best to use for this problem. Im new in physics and am pretty mathmetically challenged so any help would be greatly appreciatied
  2. jcsd
  3. Oct 25, 2007 #2


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    The simplest case is assume it flys around the equator at the same speed the earth rotates, so it always has the same local (sun) time.
    Then you just need the cicumference of the earth (hint definition of the metre) and the time taken for the earth to rotate (for extra credit - this isn't 24hours).

    For 40deg lat just work out what the diamter of earth is at that latitude, it only involves drawing a triangle.

    To make it more complicated, you could assume it takes off at dawn and lands in the same place just before dusk, it would still have been in sunlight but doesn't need to have flown as fast. This might be overcomplicating the question for a beginner class.
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