Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Homework Help: Power of Elevator

  1. Oct 25, 2008 #1
    1. The problem statement, all variables and given/known data
    An elevator has a mass of 956 kg and car-
    ries a maximum load of 764 kg. A constant
    frictional force of 4150 N retards its motion
    upward.
    The acceleration of gravity is 9.8 m/s2 .
    What power must the motor deliver at a
    instantaneous speed of 4.69m/s if the elevator
    is designed to provide an upward acceleration
    of 1.07 m/s2? Answer in units of W.



    3. The attempt at a solution

    F=ma
    N-mg=(me+ml)a
    N=(me+ml)(a+g)
    F=N-frictional force
    P=Fv

    I was wondering if this progression of the problem would be logical to solve for the power.
     
    Last edited: Oct 25, 2008
  2. jcsd
  3. Oct 25, 2008 #2
    I got it:

    Fy=ma
    N-mg-f=ma
    N=(me+ml)(g+a) + friction

    P= Nv

    =107144.616
     
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook