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Plane direction and veloctiy question

  1. Sep 24, 2006 #1
    alright, here is the question and how far i got.

    A light plane is travelling at 175km/h on a heading of N8[degree]E in a 40km/h wind from N80[degrees]East. Determine the planes ground velocity

    im going to skip the notations so..

    planes velocity relative to the air is (175cos8, 175sin8)
    = (173.2,24.3)

    air velocity relative to the ground is (40cos80, 40sin80)
    = (6.94,39.4)

    you add both and get (180.14,63.7)

    and the magnitude which is the velocity of the plance relative to the air is 191.07km/h

    191.07km/h is wrong, it should be 167 km/h.

    I dont understand what i am doing wrong.
    Yes, i do know how to find the direction, but if the speed is wrong there is no point in trying to find the direction becuase it too would be wrong. any ideas on how to fix?
  2. jcsd
  3. Sep 24, 2006 #2


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    Homework Helper

    Draw your vectors, it will be more easy to determine what you're doing wrong.
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