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Power and elevators

  1. May 3, 2010 #1
    Question: The loaded cab of an elevator has a mass of 3.0 103 kg and moves 191 m up the shaft in 23 s at constant speed. At what average rate does the force from the cable do work on the cab? answer is in kW

    hint provided : Power is the rate at which work is done. The power of a force is the dot product of the force and the velocity. If the cab moves at constant speed, how does the cable's force compare with the gravitational force on the cab?

    So im guessing tension which equals mg is our force, and so that force times velocity, which is 191/23 m/s is our power. what did i do wrong? how do you solve this properly? thank you! :D
  2. jcsd
  3. May 3, 2010 #2


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    Welcome to PF!

    Hi themanofosu ! Welcome to PF! :smile:

    (try using the X2 tag just above the Reply box :wink:)

    You haven't actually shown us your final figures, but your method looks correct …

    did you remember to convert from W to kW ? :smile:
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