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Elliptical orbits, Kepler

  1. Oct 20, 2014 #1
    hey everyone, this is a qualitative question on gravitational orbits:

    I was going through questions in which the trajectory of the orbiting body is determined based upon the eccentricity of the orbit, e.g. 0<Ecc<1, ellipses, Ecc=1, parabola, Ecc>1, hyperbola. I did the math and found out what the foci where for each case. But I would very much like to know, what is the physical meaning of these foci? Yes, they are points such that the sum of distances from a point on the circumference of trajectory to each focus is a constant. But what do they really mean, in terms of forces or whatever?

    Okay, thanks!
  2. jcsd
  3. Oct 20, 2014 #2


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    As a side point, this is true only for the ellipse, not the parabola or the hyperbola.
  4. Oct 25, 2014 #3
    Only one focus counts.
    Here is the basic data sheet, you might get something from it.

    Attached Files:

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