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Internal work

  1. Nov 15, 2007 #1
    in the problem they give you V=44m/s, mass=.09 kg , and a vertical distance=18m
    the problem states that a ball is shot straight down and at the distance 18m it encounters a sand bag the ball goes through the sand bag .5 m. they ask what is the internal work neglecting friction??????????
    for this problem I have

    -w=-mgh-.5mv^2

    now I am confused for h do I use 18 m or 18.m ????
     
    Last edited: Nov 15, 2007
  2. jcsd
  3. Nov 15, 2007 #2

    Dick

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    You use the distance over which gravity was doing work on the ball. Which is that?
     
  4. Nov 16, 2007 #3
    the distance that gravity is doing work on the ball will be 18m ??
     
  5. Nov 16, 2007 #4

    Dick

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    The distance gravity is doing work on the ball is the vertical distance that the ball moves. Gravity doesn't shut off inside the bag.
     
  6. Nov 16, 2007 #5
    oh so the distance will be 18.5m I thought that .5 was the distance that the internal force is acting on the object Work = F*d
     
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