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Measuring Constant of Gravitation in Basement - Experiment

  1. Apr 5, 2009 #1
    The other day I was reading a simple experiment to determine (yes, very roughly) the constant of gravitation, all using simple tools in your basement.

    http://www.fourmilab.ch/gravitation/foobar/" [Broken]

    What struck me about this experiment is another that I remember from childhood cartoon shows - using a free-swinging pendulum which will 'rotate' due to earth's rotation over the course of a day. I suddenly got the notion in my head that this gravitation experiment, where the two masses are hung by a string, might be affected by natural rotation! Someone please either confirm this potential error, or help me get this doubt out of my head.

    PS: I'm assuming the damping 'stuff' is the solution to my question, if anyone can fill in the blanks it would be greatly appreciated.
    Last edited by a moderator: May 4, 2017
  2. jcsd
  3. Apr 5, 2009 #2
    The experiment in the link you provided is a torsion balance. It is not influenced by the Earths gravitational field or rotation in the same way that a pendulum is. It's motion is almost entirely determined by the masses used in the experiment.
  4. Apr 6, 2009 #3
    Thank you TurtleMeister, I'm sure I'll learn more about these later on, but thanks for clearing any doubts.
  5. Apr 6, 2009 #4


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    It's not impossible, we use to do it as an ugrad practical lab. the only 'special' equipement we used was an internal room in a basement (an old darkroom) that was well insulated from vibration and temperature changes.
    We used a telescope viewing through a window in the wall rather than a camera.
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