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Homework Help: Need help on this problem please I cant figure it out

  1. Oct 12, 2004 #1
    Need help on this problem please!! I cant figure it out!!

    The problem is A 54.0 kg. skateboarder starts out with a speed of 1.90 m/s. He does +80.0 J of work on himself by pushing with his feet against the ground. In addition, friction does -265 J of work on him. In both cases, the forces doing the work are nonconservative. The final speed of the skateboarder is 5.90 m/s.
    (a) Calculate the change (PE = PEf - PE0) in the gravitational potential energy?
    J
    (b) How much has the vertical height of the skater changed?
    m
    (c) Is the skater above or below the starting point?
    above the starting point or
    below the starting point ?
     
  2. jcsd
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