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Homework Help: Scales- Weight on a scale in an elevator (True/False) Quick!

  1. Feb 4, 2009 #1
    1. The problem statement, all variables and given/known data

    The figures depict situations where a person is standing on a scale in eight identical elevators. Each person weighs 600 N when the elevators are stationary. Each elevator now moves (accelerates) according to the specified arrow that is drawn next to it. In all cases where the elevator is moving, it is moving upward.


    Which of the following statements are true about the situations depicted in the figures above?

    The mass of the person is different in pictures B and H
    The weight the scales read is the same in pictures A, B, C and H
    The normal force provided by the scale is zero in pictures G and H
    The net force on the person is zero in pictures D, E and G
    The scales read zero weight in pictures C, D and F

    2. Relevant equations

    3. The attempt at a solution

    1. False, mass stays the same. It says each person ways 600N when the elevator is stationary.
    2. False, different accelerations read different weights
    3. False, wouldn't there be one?
    4. True, force on person is zero, force on scale is something else.
    5. False, acceleration of gravity is there

    Where am I going wrong?
    Last edited: Feb 4, 2009
  2. jcsd
  3. Feb 4, 2009 #2
    due in 20 minutess!! help
  4. Feb 4, 2009 #3
    I'm perhaps not the best person to reply to this, because my knowledge about elevators is very limited. But just using logic:

    When you accelerate down in an elevator, don't you feel lighter? For #3 - since you accelerate down with a=g, and gravity is still there, won't they sort of cancel out? So you'll feel weightless and if you feel weightless there shouldn't be a normal force.
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