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Homework Help: Energy Bars

  1. Jun 18, 2007 #1
    1. The problem statement, all variables and given/known data

    http://img256.imageshack.us/img256/795/untitledpw7.jpg [Broken]

    3. The attempt at a solution

    I know Ug stands for the gravitational potential energy, but I'm not sure what Us and Uint stands for.

    At initial stage 1, I know the ball has kinetic energy and also has had work applied on it (the goalkeeper kicking the ball), but how do I know how much work is being applied?
    Last edited by a moderator: May 2, 2017
  2. jcsd
  3. Jun 18, 2007 #2


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    Homework Helper

    You are in serious trouble with this question. I think you would need to consult your Physics handbook to solve it (or get help from the lecturer/other scolars in the class).

    My guess is that the g refers to the earth and the s refers to the soccer ball while the int refers to a change in internal potential energy. It is not clear (at all) what is on the x- and y-axii. That is why I think you should look in the handbook or ...

    My take on it is that the goalkeeper injects energy into the ball/earth system by kicking it. If air friction were not present the sum of all energies would remain constant, but I have a sneaky fealing that in this case one should assume that air friction removes energy from the system.
    Last edited: Jun 18, 2007
  4. Jun 18, 2007 #3
    LOL. Oh well, I tried!
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