Kepler's 3rd Law, circular orbit, 2 planets

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SUMMARY

Kepler's 3rd Law applies to circular orbits of two planets, where the mass of the planets is negligible compared to the mass of the central body. The relevant equations are T² = (4π²a³)/(GM) for the orbital period and E = - (GMm)/(2a) for energy. The discussion confirms that the presence of two planets does not alter these equations, as the gravitational influence of the planets on each other can be ignored when their masses are significantly smaller than the central mass.

PREREQUISITES
  • Understanding of Kepler's Laws of Planetary Motion
  • Familiarity with gravitational equations, specifically T² = (4π²a³)/(GM)
  • Basic knowledge of circular orbits and energy equations in astrophysics
  • Concept of mass ratios in gravitational systems
NEXT STEPS
  • Study the implications of mass ratios in gravitational interactions
  • Explore advanced applications of Kepler's Laws in multi-body systems
  • Learn about perturbation theory in celestial mechanics
  • Investigate the effects of non-negligible masses in orbital dynamics
USEFUL FOR

Students studying astrophysics, educators teaching planetary motion, and anyone interested in the mathematical modeling of celestial orbits.

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Homework Statement


http://www.its.caltech.edu/~tmu/ph1a/FPs/fp12.htm
this is the question.

Homework Equations



T^2=\frac{4\pi^2a^3}{GM}

E=-\frac{GMm}{2a}

The Attempt at a Solution



I have none. My question is, does the fact that there are two planets affect the equations for period and energy? Without knowing this, I can't solve any of it. Help? Slightly urgent. This problem is due tomorrow at 4pm PST.
 
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Well, since m << M, I would say that you can ignore any effects which the planets have on each other, so no, you don't need to change the period and energy equations.
 
Thanks.
 

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