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Homework Help: Mechanical Energy lost

  1. Apr 16, 2005 #1
    A crate of mass 10.0 kg is pulled up a rough incline with an initial speed of 1.50 m/s. The pulling force is 100 N parallel to the incline, which makes an angle of 20 degrees with the horizontal. The coefficient of kinetic friction is 0.400, and the crate is pulled 5.00 m. How much mechanical energy is lost due to friction and what is the change in kinetic energy of the crate?

    I figured out the kinetic energy initially, and i got 11.25 J. For the final kinetic energy i got 501.00 J(using the equation KE=1/2*m*v2(squared).

    How do i find the change in kinetic energy? do I subtract the final from initial ? and for the mechanical energy lost doing friction, how does the friction fit into the equation?
  2. jcsd
  3. Apr 16, 2005 #2


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    How did u get that 501J...?HINT:use the theorem of variation of KE.How many forces act on the crate and how many of them do work on the crate...?

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