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Homework Help: Help please Problem on Acceleration

  1. Sep 5, 2004 #1
    help please!! Problem on Acceleration

    The land speed record of 13.9 m/s (31 mi/h) for birds is held by the Australian emu. An emu running due south in a straight line at this speed slows down to a speed of 10.5 m/s in 2.7 s.

    What is the direction of the bird's acceleration?

    Assuming that the acceleration remains the same, what is the bird's velocity after an additional 3.9 s has elapsed?
     
  2. jcsd
  3. Sep 7, 2004 #2

    JasonRox

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    Hint:

    [tex]a=\frac{v_f-v_i}{t}[/tex]
     
  4. Sep 8, 2004 #3
    Hint: If it slows down it is decelerating i.e negative acceleration
     
  5. Sep 8, 2004 #4

    HallsofIvy

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    Also, "speeding up" means speed is increasing: acceleration is "positive"- in same direction as velocity.

    "Slowing down" means speed is decreasing: acceleration is "negative"- in opposite direction to velocity.
     
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