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Homework Help: Acceleration due to gravity

  1. Jul 26, 2009 #1
    I did an experiment with water balloons and i dropped it off at a specific height. The acceleration of the object is nowhere near 9.81m/s^2
    Why is that?
  2. jcsd
  3. Jul 26, 2009 #2


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    Welcome to PF:

    If you drop a rigid body, its acceleration due to gravity will be nearly 9,8 m/s^2
    But the water balloon is not a rigid body.
  4. Jul 26, 2009 #3
    rigid as in?
  5. Jul 26, 2009 #4


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    Well, rigid in this context means "doesn't deform in any way." Every point within that body remains at a fixed position relative to all the other points, and these relative positions don't change. This is an idealization. There is no such thing as a rigid body in real life.

    If I had been answering your original question, I would have cited air resistance (drag) as something to be looked into. I.e. you are not dropping this thing in a vacuum, and therefore gravity is not the only force acting on it.
  6. Jul 26, 2009 #5
    thank you very much
  7. Jul 26, 2009 #6


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    What did you get for the acceleration?
  8. Jul 26, 2009 #7
    More importantly, for what height and time did you make the measurements?

    The oscillations of the balloon and the approach towards the terminal velocity (When the velocity is at the terminal velocity, the balloon will no longer accelerate) could have immense impacts on the average acceleration, flooring its value if you take a measurement over a long enough time.
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