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Homework Help: 2D kinematics? Have equations but making errors?

  1. Nov 13, 2008 #1
    When Babe Ruth hit a homer over the 7.5-m-high right-field fence 95 m from home plate, roughly what was the minimum speed of the ball when it left the bat? Assume the ball was hit 1.0 m above the ground and its path initially made a 38º angle with the ground

    2. Vx= Vcosθ x=horizontal distance, T=time, L=initial height h=final height
    Vy= Vsinθ

    x=vcosθT = x / vcosθ = T
    h= L + vsinθT - (1/2)gT^2

    3. The attempt at a solution

    substituting for T

    h= L + vsinθ(x / vcosθ) - (1/2)g(x / vcosθ)^2
    h=L + xtanθ - (1/2)gx^2/ v^2 cosθ^2

    v= sqrt[(L + xtanθ - (1/2)gx^2/cosθ^2) / h]

    this should be how to get my answer which is 32, but I keep getting a number in the 90s. I actually get a negative under the sqaure root...but I ignore that...
  2. jcsd
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