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Just hypothetical thinking

  1. Feb 21, 2007 #1
    If the earth was flat, and there were no such thing as gravity, and it, along with all the celestial bodies, accelerated upwards (so, parallel to normal) at 1g(9.8m/s^2), what would happen if I dropped a pen while I am on earth?
  2. jcsd
  3. Feb 22, 2007 #2
    The pen would maintain it's current speed.
  4. Feb 22, 2007 #3

    So, it'd still seem that gravity existed, right?
  5. Feb 22, 2007 #4
    no,the pen wouldnt accelerate therefore,it wudnt seem as if gravity existed
  6. Feb 22, 2007 #5
    For a casual observer who is accellerating with this flat earth, the pen would appear to be accellerating down.
    But that is because the observer is accustomed to being accelerated upwards by the earth under his feet, not because the pen actually is going down.
  7. Feb 22, 2007 #6
    You could actually do an experiment and determine that you were accelerating and the pen was the "inertial frame". However, I would have to ask the question: why would you ask this question? It almost seems like something the Flat Earth Society would do to try and get a bunch of "physicists" to support their views.
  8. Feb 22, 2007 #7


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    I have the same suspicion as StatMechGuy.

  9. Feb 22, 2007 #8
    So harsh guys! This is the legitimate basis of general relativity. It would be very difficult to distinguish this kind of acceleration from "gravity" (you'd need to compare measurements from separated places, much as were used the first time to show we don't live in a discworld).
  10. Feb 22, 2007 #9


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    Yeah, but one doesn't need to do that on a "flat" earth! An ordinary earth that we have right now is pretty sufficient, don't you think?

    Furthermore, I don't think we were being "harsh". All I said was I had a "suspicion". It wasn't an accusation. If I think truly believe this is nothing more than a flat-earth advocacy, do you think this thread would have survived till now?

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