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Homework Help: Relative speed of flying bird?

  1. Jan 23, 2007 #1
    1. The problem statement, all variables and given/known data
    speed of man=120m/h
    angle of bird flight with ground=60 degrees.

    2. Relevant equations
    A man on the ground sees a bird flying at angle of 60 degrees with horizontal.He started running at 120m/hour,is able to stay directly below the bird.What's bird speed?

    3. The attempt at a solution

    I've vainly tried to solve it by using vectors.But I'm uncertain how it'd be solved?
    Last edited: Jan 23, 2007
  2. jcsd
  3. Jan 23, 2007 #2
    draw a triangle. the base is 120 for the man. if they are moving to the right, the angle is 60 upward to the right. the tangent of that angle is tan 60 = x/120. Therefore the equation is 120 tan 60 = x = 120 radical 3. then do Pythagorean theorem to find the hypotenuse (or flight of the bird) is 240.
    ( if you know the way 30-60-90 triangles work, you wouldn't need all that work)
  4. Jan 24, 2007 #3
    Thanks for nice help.U've pointed me in the right direction.
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