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Homework Help: Determine original velocity (kinematics)

  1. Sep 25, 2009 #1
    1. The problem statement, all variables and given/known data

    if a ball hit by a racket at an angle of 3 degrees reaches a height of .330m at its trajectory, how fast was the ball moving when it left the racket?

    2. Relevant equations

    d=Vot + 1/2at^2

    3. The attempt at a solution

    Vox = Vocos(3dgres)
    Voy = Vosin(3dgres)

    h(max)= Vy=0

    so Voy= -at?

    i think i have to find the time it takes to reach the max height, then im lost... please help
  2. jcsd
  3. Sep 26, 2009 #2

    Doc Al

    User Avatar

    Staff: Mentor

    Sure. Now combine that with your first equation (d=Vot + 1/2at^2) and you can solve for the time it takes to reach max height.

    That's not the only way to go. You can also invoke another kinematic formula that directly relates distance and velocity for accelerated motion.
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