On Feynman’s analysis of the geometry of Keplerian orbits

@article{Kowen2003OnFA,
  title={On Feynman’s analysis of the geometry of Keplerian orbits},
  author={Michael Kowen and Harsh Mathur},
  journal={American Journal of Physics},
  year={2003},
  volume={71},
  pages={397-401}
}
A geometrical construction, introduced by Maxwell and Feynman to demonstrate that closed Keplerian orbits are elliptical, is adapted to show that open Keplerian orbits are hyperbolic or parabolic. 
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