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Homework Help: Work problem

  1. Nov 3, 2005 #1
    Hi, I'm having problems with this question:

    ok first I determined what work that gravtity does which is m*g*(delta y) which in this case is -50 J

    I then used the CEW theorem equation using the velocities to find the total work done: (sigma W) = 1/2 m (v^2 (final) - v^2(initial)) which is -62 J

    Last part is that I used the relationship between the work of gravity and the total work (sigma)W = W of gravity + Work of air resistance. I got -12 Joules for air resistance. I don't know but I feel like I got something wrong here. Can anyone help me out?
  2. jcsd
  3. Nov 3, 2005 #2


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    Homework Helper

    Well, the difference between the kinetic energy at the bottom and the potential energy at the top will be the amount lost due to air resistance.

    E_a = (1/2)mv^2 - mgh = 61.7 - 50
    = 11.7J

    W_a = E_a
    = 11.7J

    I don't know the method you have used.

    Edit: Work is a scalar I see.
    Last edited: Nov 3, 2005
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