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Work Done by Pitcher

  1. Oct 31, 2007 #1
    [SOLVED] Work Done by Pitcher

    1. The problem statement, all variables and given/known data

    A baseball leaves a pitcher's hand at a speed of 32.5 m/s. The mass of the baseball is 0.145 kg. You can ignore air resistance.

    How much work has the pitcher done on the ball by throwing it?

    3. The attempt at a solution

    velocity initial = 32.5
    velocity final = 0 (it has to stop eventually right?)
    mass of ball = .145

    K = mv^2

    K1 = (.145)(32.5)^2 = 153.16
    K2 = (.145)(0)^2 = 0

    Wtotal = K2-K1

    Wtotal = 0 - 153.16

    :confused:

    Solution: 76.6 J
     
  2. jcsd
  3. Oct 31, 2007 #2

    Doc Al

    User Avatar

    Staff: Mentor

    They are talking about the work done by the pitcher in taking a ball from rest to its top speed as it leaves his hand.

    That's not quite right.
     
  4. Oct 31, 2007 #3
    haha,

    I forgot it was

    K = 1/2mv^2

    ok, now that I got 76.58.

    ah, I see now.

    so it's this then

    K2 = .5(.145)(32.5)^2 = 153.16
    K1 = .5(.145)(0)^2 = 0

    Wtot = K2-K1 = 76.58
     
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