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Apparent Weight Elevator Speed

  1. Oct 5, 2008 #1
    1. The problem statement, all variables and given/known data
    Referring to the problem above, if the elevator's descending speed is measured at 10 m/s at a given point, but its speed is decreasing by 2.5 m/s2, what is her apparent weight?.
    And the problem above it was this
    A 58.0 kg girl weighs herself by standing on a scale in an elevator. What is her apparent weight when the elevator is descending at a constant speed of 10 m/s?


    2. Relevant equations
    So i was able to find the answer to the first question which was 568N and found it by doing her mass times the gravity. but i have no i idea of how to do it when the speed it decreasing.


    3. The attempt at a solution
    i tried doing her mass times her acceleration which was 10m/s and that was wrong and so i then tried doing her mass time her deceleration of 2.5m/s/s and that was wrong as well. if you could just help with an equation that should be good enough. thanks
     
  2. jcsd
  3. Oct 6, 2008 #2

    Kurdt

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    Her apparent weight will be the weight due to gravity plus the force exerted on her by the lift.
     
    Last edited: Oct 6, 2008
  4. Oct 6, 2008 #3
    ok so i would use my initial number of 568N and add that to what? her mass times the deceleration?
    cool so i put that in and it does work, thanks man
     
  5. Oct 6, 2008 #4

    HallsofIvy

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    Yes, force = mass times acceleration. If the elevator is accelerating upward, then you would feel g+ mass * acceleration. If the elevator is accelerating downward, then you would feel g- mass*acceleration.
     
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