Physlet Illustration: Kepler's Second Law

 

 

Interactive Help
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A planet orbits a star under the influence of gravity. The distance grid is in Astronomical Units (AU), and the time is shown in years.  The animation begins from the point of aphelion, and the total area swept out by the planet's orbit is given in AU2. Can you verify Kepler's Second Law?

Hints:

  1. Starting at t = 0, run the animation for a certain time interval. How much area has been swept out by the planet in this time interval?
  2. Now, continue the animation for a second time interval of equal duration. How much total area has now been swept out? How much area, then, was swept out in the second time interval?
  3. Can you verify Kepler's First Law, as well? What is the eccentricity of the elliptical orbit?
  4. Turn on the Interactive Help. How does the planet's speed (shown in AU/yr) vary as it executes its orbit?

Reference

See Walker, Section 12-3

Illustration written by Steve Mellema