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Energy and Power Question

  1. Apr 21, 2007 #1
    1. The problem statement, all variables and given/known data
    The motor of an elevator can produce 14kW of power, its mass is 1100kg. At what constant speed will the elevator rise?

    2. Relevant equations
    W= Fd
    P= w/t
    Vav= d/t

    3. The attempt at a solution
    P= w/t
    P= Fd/t
    P= F * Vav
    V= P/mg = 14000W/(1100Kg*9.8m/s^2)=1.29m/s

    The book states the answer is 13m/s. I have no idea how I'm suppose to get this answer, please help. Thanks in advance.
  2. jcsd
  3. Apr 21, 2007 #2


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    Homework Helper

    Hmmm, seems like there is a factor of ten missing somewhere. Are you sure you are using all the right values? Perhaps the book is wrong.
  4. Apr 21, 2007 #3


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    Homework Helper

    As you've derived, the equation P = Fv is correct, so it looks like a mistake in the book. An elevator going 13 m/s seems a bit fast if floors are approx. 5 meters apart.
  5. Apr 21, 2007 #4
    Ok thanks guys.
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