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Type of curvature of gradient force from edge to center of a sphere

  1. Jun 5, 2013 #1
    I was doing some simple physics with a ball resting on a table and I made this curve

    (0,0) (25, 6.8) (50, 27.51) (75, 63.4) (100, 112.34) (125, 175.7) (150, 253.3) (175, 345.4)

    I was wondering if anyone could identify what sort of curve it is? I am just curious.

    This is not a homework problem.
  2. jcsd
  3. Jun 5, 2013 #2


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    Why can't you plot this out, post it here, and tell us what you think?

  4. Jun 5, 2013 #3
    I got the points off of a curve that developed due to the the apparent force of gravity pushing a sphere down on a table...I cant tell if it is hyperbolic or parabolic...or maybe a section of an ellipse(if thats even different)...I have seen the curve and I am guessing it is a parabola but I am not sure how to be certain because I could do a quadratic regression in my calculator but that wouldnt really prove anything would it?
  5. Jun 5, 2013 #4
    Here is a picture of the curve


    Hyperbole, Parabola, or a section of ellipse I cant tell the difference
  6. Jun 5, 2013 #5


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    I did a curve fit on Excel
    The ordered pairs you gave at the beginning lie very close to a perfect parabola:
    y = 0.011329238095238*x^2 - 0.009373809523815*x - 0.037083333332703
    with R^2 of 0.999997
  7. Jun 5, 2013 #6
    Thanks man, I wonder why the force over the gradient of the circle translates proportionally into a practically perfect parabola?

    I will have to do some more investigating!

    Thanks again for your reply.
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