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Pressure exerted in an elevator

  1. Jul 30, 2006 #1
    A suitcase (mass m=16kg) is resting on the floor of an elevator. The part of the suitcase in contact with the floor measures 0.50m by 0.15m. The elevator is moving upward, the magnitude of its acceleration being 1.5m/s^2. What pressure (in excess of atmospheric pressure) is applied to the floor beneath the suitcase?

    This problem isn't too hard. Elevator is going up so the pressure will be greater than normal produced by the suitcase. Take the area of the suitcase and continue from there?
     
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  3. Jul 30, 2006 #2

    Andrew Mason

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    What is the force exerted on the suitcase by the floor? What is the area over which this force acts? That should be all you need.

    AM
     
  4. Jul 31, 2006 #3
    When calculating the force do I just add 1.5m/s^2 to 9.8m/s^2 and then calculate the force per area from there?
     
  5. Jul 31, 2006 #4

    Andrew Mason

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    Conceptually, the acceleration and gravity are different. You would add the force of gravity (weight) which the floor applies with no acceleration, to the force which the elevetor applies to accelerate the suitcase:

    [tex]F_{normal} = ma + mg[/tex]

    AM
     
  6. Jul 31, 2006 #5

    HallsofIvy

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    Of course, that's just
    [tex]F_{normal}= m(a+ g)[/tex]
    as KingTutAtl asked.
     
  7. Jul 31, 2006 #6

    Andrew Mason

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    Of course. I should have begun my answer with: "Yes, provided you multiply by the mass". It appeared to me that the op was uncertain as to why you would add them together, since there is no acceleration due to gravity.

    AM
     
    Last edited: Jul 31, 2006
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