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Homework Help: Will you check my work?

  1. Feb 3, 2009 #1
    1. The problem statement, all variables and given/known data
    A left-handed pitcher at sea level throws a baseball at a 45o angle with an initial speed of 19 m/s. The time for the ball to reach its highest point can be found from the data and known constants using which equations? Solve for the time.

    2. Relevant equations
    V^2 = Vi^2 + 2(a)(y)
    y = (Vi)(t) + 1/2(a)(t^2)

    3. The attempt at a solution
    V^2 = Vi^2 + 2(a)(y)
    0 = 13.435^2 + 2*9.8*y
    y = 9.21 meters

    9.21 = 0 + 0.5*9.8*t^2
    9.21 = 4.9*t^2
    t = 1.37 seconds
  2. jcsd
  3. Feb 3, 2009 #2


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    Gold Member

    Yes, correct, but you could have shortened your work by using just one simpler equation. Can you identify that equation?
  4. Feb 3, 2009 #3
    Looks okay.
    I used this:

    velocity at the highest point is 0, so..

    0[tex]m/s[/tex] =19[tex]m/s[/tex] sin45°-9.8[tex]m/s^{2}[/tex] *t
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