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Homework Help: Can someone help me please

  1. Nov 4, 2007 #1
    The airspeed of a small plane is 200 km/h. The wind speed is 50.0 k/h from the west. Determine the velocity of the plane relative to ground if the pilot keeps the plane pointing to each of the following directions:
    a) [E] b) [W] c) [N] d) [N400E]

    I never learned this stuff but it is on my homework, can anyone give me formula to solve this problem please?..
  2. jcsd
  3. Nov 4, 2007 #2


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    This is a problem of vector addition.

    The 200 km/h is the magnitude airspeed (speed of plane relative to the air) and the problem gives 4 orientations, which then defines that vector, to which one then adds the velocity of the wind.

    Since the wind if from the west, it is moving toward the east, so take E as the + direction, and denote the unit vector as i. For the opposite direction, W, the vector would be -i. Similarly N would be +j or j and S would be -j.

    Take part a. The plane if flying E at 200 km/h with respect to the air, and the air is moving E at 50 km/h. Adding the two vectors, one gets 200 i + 50 i = 250 i, so the plane is moving 250 km/h due E.

    Now try the others.

    See this reference - http://hyperphysics.phy-astr.gsu.edu/hbase/airpw.html
  4. Nov 4, 2007 #3
    Thankyou very much sir
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