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What is the initial projectile speed of the ball?

  1. Jan 13, 2007 #1
    The pitcher in a slow-pitch softball game releases the ball at a point 3.0 ft above ground level. A stroboscopic plot of the position of the ball is shown in the figure below, where the readings are 0.25 s apart and the ball is released at t = 0. On the horizontal axis, x1 = 20 ft.

    (a) What is the initial speed of the ball?
    (b) What is the speed of the ball at the instant it reaches its maximum height above ground level?
    (c) What is that maximum height?

    i tried to find part c first. since i know that time is equal to 1.25 seconds i used deltay=.5at^2
    25 feet
    this did not work so I do not know what to do?
    any one with any help. thaks

    Attached Files:

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  2. jcsd
  3. Jan 13, 2007 #2


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    Why are you using t=1.25s in your calculation? That isn't the time it takes the ball to get to maximum height.
  4. Jan 13, 2007 #3
    If you can answer (b), that will help you answer (c).

  5. Jan 14, 2007 #4

    Gib Z

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    u=0 i think
  6. Jan 14, 2007 #5


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    u can't be zero as the ball is pitched!
  7. Jan 14, 2007 #6
    i am still not getting the answer. I also tried time as 1.25/2 but this is stil not right?

    any one please
  8. Jan 15, 2007 #7


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    1.25/2 is the time to the maximum height. The equation you were using gives the change in height from where it started. Don't forget it was 3 ft above the ground when it was thrown. So if you want the total height above the ground you have to take that into account.

    Does that help?
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