The motion of a particle in an inverse-square field of force is described in terms of the potential energy, which depends on the distance r from the center of force, and the kinetic energy, which can be expressed in terms of an effective impact parameter h⁠. In different cases the relations between r and h correspond to paths which are elliptic, parabolic, and hyperbolic. These results are based on elementary geometry, which is sufficient to derive Kepler's third law and the Rutherford formula for nuclear scattering of alpha particles.

Topics
Alpha particles, Kepler's laws, Nuclear scattering, Impact parameter
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© 1962 American Association of Physics Teachers.
1962
American Association of Physics Teachers
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