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Work input/output, efficient probelm, just need someone to check my work

  1. Nov 28, 2007 #1
    Work input/output, efficient probelm, just need someone to check my work :)

    1. The problem statement, all variables and given/known data
    Because there is very little friction, the lever is an extremely efficient simple machine. Using a 90% efficient lever, what input work is required to lift an 18kg mass through a distance of 0.5m?


    2. Relevant equations

    (Fout/Fin)/(Din/Dout)

    3. The attempt at a solution

    (Fout/Fin)/(Din/Dout)
    (176.6N/Fin)/(Din/.5m)=.9

    so you get (Fin)(Din)=98.1 which FD is work so 98.1J is the answer correct?
     
  2. jcsd
  3. Nov 28, 2007 #2
    Well, I do not quite understand (Fout/Fin)/(Din/Dout) as being an "equation". There is no = sign!

    That said, when I work the problem, my answer matches yours. I think you mean to write (Fout/Fin) = (Din/Dout), which is legitimate!
     
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