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Homework Help: Relative Velocity of a plane

  1. Jun 7, 2008 #1
    a,The Speed Of an aircraft in still air is 300 km/h.
    In a wind of speed 140 km/h, blowing from a bearing of 230, the aircraft flies due east. Find
    i, the course set by the pilot
    ii, the time taken for the aircraft to travel 100 km.

    b,To a cyclist traveling due east at 18 km/h the wind appears to be blowing at 12 km/h from a bearing of 150. Find the true wind-speed and the direction from which the wind is blowing.
  2. jcsd
  3. Jun 7, 2008 #2


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    Where's your attempt at a solution?
  4. Jun 7, 2008 #3
    how to draw a vector diagram ?? of the above problem?? I only have problem in that...
  5. Jun 7, 2008 #4
    its all simple trigonometry .... after that... i need to know what will be the direction of Aircraft in still air? what does that mean? what will be the direction of of wind... how will we create a vector diagram...of it?
  6. Jun 7, 2008 #5
    You should be able to draw 3 vectors, where one of them is the final speed and direction of the moving object(which you can find by vector addition).
  7. Jun 8, 2008 #6


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    Hi Zoheb! :smile:

    Give them letters!

    Call the plane P, the air A, and the ground G.

    Then P - A = 300, and A - G = 140 @ 230º.

    And you know that P - G is 90º.

    Draw a triangle with an arrow on each side, so that the arrow along P - A goes the same way as the arrow along A - G (in other words, it doesn't meet it head-on).

    Does that make sense? :smile:
    Not relevant … in still air, it would go at 300 in any direction … they're simply telling you how powerful the aircraft is.
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