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Homework Help: Relative velocity problem. NEED HELP.

  1. Sep 11, 2007 #1
    1. The problem statement, all variables and given/known data
    A jet airliner moving initially at 300 mph due east enters a region where the wind is blowing at 100 miph in a direction 30° north of east. What is the new velocity of the aircraft relative to the ground?


    2. Relevant equations
    I don't know any equations for this question.


    3. The attempt at a solution
    I thought it might be like using the 300 mph... caculate the hypotenus velocity vector using the angle, and add 100 mph... I don't think it's right.
     
    Last edited: Sep 11, 2007
  2. jcsd
  3. Sep 11, 2007 #2

    Astronuc

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    This is a vector addition problem. One adds the planes velocity vector to the winds velocity vector. The plane is supported/carried by the wind and the wind is moving, which is much like a boat in a river with a current.

    So pick a coordinate system, and the determine the components of each vector.

    Pick the direction to East as +x, and the direction to North as +y.
     
  4. Sep 11, 2007 #3
    Oh wait... so if the plane's velocity vector was A, and the wind's velocity vector was B.
    It would be B + A = R?
    R being the new velocity vector relative to the ground.
     
    Last edited: Sep 11, 2007
  5. Sep 11, 2007 #4

    Astronuc

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    Correct!
     
  6. Sep 11, 2007 #5
    Thank you very much. Much easier when you have another to think with.
     
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