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Question about gravity

  1. Sep 18, 2008 #1
    I'm just wondering, when I'm in an elevator going up/down when do I feel lighter?
     
  2. jcsd
  3. Sep 18, 2008 #2
    I could be wrong, but I believe you will feel lighter as you go with gravity and feel heavier when you go against gravity. So when you go up you are going against gravity and thus will feel heavier.
    This is my logic of thinking anyways...no idea if it is correct.
     
  4. Sep 18, 2008 #3

    DaveC426913

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    "Lighter" and "heavier" are sensations that are relative to our sense of up and down.

    You will feel lighter when you accelerating in the direction of your feet (i.e. down), and heavier when accelerating in the direction of your head (i.e. up).

    You are accelerating down at the top of an elevator ride (whether it is a ride up or a ride down). You are accelerating up at the bottom of an elevator ride (whether it is a ride up or a ride down).
     
  5. Sep 18, 2008 #4
    but when would you say you feel lighter, at the beginning, middle or end of the elevator ride??
     
  6. Sep 18, 2008 #5
    when you are at the top and the elevator is stopping. You will feel lighter because the elevator is accelerating downword, with gravity and your body in motion, according to one of newtons laws, will continue in motion giving you somewhat of a free falling feeling.
     
  7. Sep 29, 2008 #6

    DaveC426913

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    As well as when you are at the top and the elevator is starting (down).
     
  8. Sep 29, 2008 #7
    it depends on which direction you are going, if the elevator is going up, the force you feel is m(a+g) where a is the acceleration of the elevator and g is acceleration of gravity.
    If you are going down, then acceleration switches direction and what you feel is m(g-a), which is the reason why you feel lighter
    hope taht answers everything
     
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