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Homework Help: Proof that gravity equals 9.8 metres per second?

  1. Aug 26, 2012 #1
    If you had to confirm that gravity equals approximately 9.8 metres per second would you take an object and drop it from different heights. Would you then take the time and displacement and work out velocity and then use that to work out acceleration??

    EDIT: In this example there is no air resistance
    Last edited: Aug 26, 2012
  2. jcsd
  3. Aug 26, 2012 #2
    the experiment wont give exactly 9.8 , since air friction is also there .
    You need vacuum or vacuum like condition for 9.8 .
    And g also varies with latitudes .
  4. Aug 26, 2012 #3
    That's why I said approximately 9.8.
    Is my method correct?
  5. Aug 26, 2012 #4
    , you need to eliminate air resistance
  6. Aug 26, 2012 #5
    Thank you
  7. Aug 26, 2012 #6
    You're method is good enough for a first order approximation.
  8. Aug 26, 2012 #7


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    Your measurement errors will be greater then the effects of air resistance unless you have some pretty exotic equipment.

    The traditional method for doing this was to fasten a strip of waxed paper tape to your weight and feed it through a sparker with a know rate. The distance between the dots give you the displacement in fixed time intervals.
  9. Aug 26, 2012 #8
    I understand. Like the "ticker tape"?
  10. Aug 26, 2012 #9
    And you can also make a pendulum of a heavy mass , light spring .
    Calculate its time period ( keep the amplitude small ) , and plug it in the equation of of time period , you can find g , pretty close enough .
  11. Aug 26, 2012 #10
    Galileo used the inclined plane.
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