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Homework Help: Projectile motion homerun

  1. Nov 4, 2004 #1
    When David Ortiz hit a homerun over the 12m high "Green Monster' fence at Fenway park 100m away from home plate, the ball was hit 1.0m above the ground at an angle of 35° above horizontal. What was the minumum speed of the batted ball?

    dx = 100m
    Vx = Xcos35°
    Vox= Xcos35°
    ax = 0
    dy = 11m
    vy = ?
    voy = ?
    ay = -9.8m/s/s
    t = ?

    That is as far as I have gotten. I have only had experience with three missing variables, not five. How do I even start this question?
  2. jcsd
  3. Nov 4, 2004 #2
    Suppose we make the initial velocity Vo. Then the initial x direction velocity is Vocos(35) and the y is Vosin(35). Can you write an equation for the displacement in the x and y directions based on your acceleration and initial velocity?
  4. Nov 4, 2004 #3
    If you're assuming that its path is parabolic and you are using some of the simple physics formulae then:

    v^2= u^2 + 2as
    (take out 'u^2' because you are calculating the vertical velocity once it reaches 1 meter above the ground after having accelerated from the point above the fence where it's vertical velocity component was equal to zero)

    v(vertical component) = sqrt(2 x acceleration due to gravity x 11)

    then you could work in the V(initial) = V_y (initial)/ sin 35 etc. etc.
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