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Homework Help: Two dimension relative morion help

  1. May 30, 2007 #1
    Two dimension relative morion help!!!!

    1. The problem statement, all variables and given/known data
    After flying for 15 min in a wind blowing 42 km/h at an angle of 18° south of east, an airplane pilot is over a town that is 60 km due north of the starting point. What is the speed of the airplane relative to the air?

    2. Relevant equations
    Velocity of plane relative to ground= Velocity of plane relative to wind+ Velocity of wind relative to ground

    3. The attempt at a solution

    Guys can you please guide me how to draw the figure of the vectores
  2. jcsd
  3. May 31, 2007 #2


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    Work out the northerly directed component of the wind speed. Then subtract this from the planes groundspeed.
  4. May 31, 2007 #3
    Is this the vector diagram i am going to make http://docs.google.com/Doc?id=dctgg53g_60dsdbbn [Broken]
    Velocity of plane relative to ground(Vpg)-Velocity of wind relative to
    ground(Vwg)= Velocity of plane relative to wind(Vpw)
    Last edited by a moderator: May 2, 2017
  5. May 31, 2007 #4


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    I guess we first best clarify the wind direction. You've shown it as blowing towards the generally southeast direction, creating a headwind component and thus the speed of the plane wrt the ground is less than its air speed. Typically, wind directions are measured from which they are blowing, that is, wind in this problem may be coming fromthe southeast, not towards it, in which case the air speed of the plane will be less than its ground speed. Can't say for sure, otherwise, your approach looks good.
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