Kepler's Third Law
Reference from the original Physics I textbook.
- Kepler's Third Law
For orbits about the same central mass M, the square of orbital period T is proportional to the cube of the semimajor axis a: T² ∝ a³. When the orbiting mass is negligible,
G = gravitational constant ≈ 6.67 × 10⁻¹¹ m³/(kg·s²); M = central mass (kg); T = orbital period (s); a = semimajor axis (m).
- Related Glossary Terms
Kepler's First Law, Kepler's Second Law, Table 3.4.1: Kepler’s Third Law
- Index
Reviewed physics notes (3)
These corrections keep the original lesson’s purpose while fixing errors in the source edition.
- Kepler’s third law uses semimajor axis, not changing instantaneous Sun-planet distance. — Reference 1
- Uses semimajor axis consistently. — Reference 1
- Clarifies the orbital distance variable. — Reference 1