Kepler's Third Law:
Kepler's Third Law states that The squares of the orbital periods
of planets are directly proportional to the cubes of the semimajor axis of the orbits.
Planetary Motion Formula:
Satellite Orbit Period:
Satellite Mean Orbital Radius:
Planet Mass:
where,
G = Universal Gravitational Constant = 6.6726 x 10^{11}Nm^{2}/kg^{2}
r = Satellite Mean Orbital Radius
M = Planet Mass
Kepler's Third Law Examples:
Case 1: The period of the Moon is approximately 27.2 days (2.35x10^{6} s). Determine the radius of
the Moon's orbit.
Mass of the earth = 5.98x10^{24} kg, T = 2.35x10^{6} s,
G = 6.6726 x 10^{11}Nm^{2}/kg^{2}.
Step 1: Substitute the values in the below Satellite Mean Orbital Radius formula:
This example will guide you to calculate the Satellite Mean Orbital Radius manually.
Case 2: Determine Jupiter's mass, which orbits Jupiter at an orbital radius of 4.218 x 10^{8}
at every 151200 seconds.
r = 4.218 x 10^{8} m, T = 151200 s, G = 6.6726 x
10^{11}Nm^{2}/kg^{2}.
Step 1: Substitute the values in the below Mass formula:
This example will guide you to calculate the Mass of the object manually.

