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Homework Help: Finding Initial Velocity in Projectile Motion Problem

  1. Aug 7, 2009 #1
    I need someone to help me find the answer to this difficult homework problem: A seagull is diving towards a stone beach at an angle of 60 degrees to the vertical releases a clam from a height of 100 meters. The clam hits the beach 3.02 seconds later. To the nearest tenth of a m/s what was its speed when it was released?

    I tried vi= m/s/sin(theta), r=2(vi^2/G)sin(60)cos(60)...???help?!?
  2. jcsd
  3. Aug 7, 2009 #2

    Chi Meson

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    Homework Helper

    I haven't a clue what you think you were doing, but stop.

    For this problem, all that matters are vertical components, so think of this as merely a "straight down free-fall" problem.

    What is the vertical displacement?
    What is the vertical acceleration?
    What is the elapsed time?

    (No sines or cosines needed so far)

    Knowing any three of the five kinematic variables means you can find the other two. Using the three that you know (above) find "initial velocity"; understand that this will actually be the vertical component of the initial velocity.
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