alleryStart learning →A moon's orbital focal point sits 50,000 km from the center of its elliptical orbit, and the orbit's eccentricity is 0.25. What is the length of the semi-major axis?
A12,500 km
B100,000 km
C200,000 km
D400,000 km
Answer & Solution
Correct answer: C. 200,000 km
1. Eccentricity is e = f / a, so a = f / e.
2. a = 50,000 km / 0.25.
3. a = 200,000 km.
_Source: OpenStax Physics (CC BY 4.0), Ch 7 "Newton's Law of Gravitation", section 7.1 Kepler's Laws of Planetary Motion_
Keep practising Newton's Law of Gravitation
Browse all Newton's Law of Gravitation questions for NCEA Level 3, or explore more Physics topics.
Related questions
Earth's closest approach to the sun is 1.47 x 10^8 km, and its farthest distance is 1.52 xEarth orbits the sun at 1.496 x 10^8 km, taking one year. Neptune orbits at 4.490 x 10^9 kMercury orbits the sun with a period of 88.0 days at an average radius of 5.791 x 10^10 m.Using G = 6.673 x 10^-11 N.m^2/kg^2, what is the gravitational force between two 60.0 kg pEarth's radius is 6.37 x 10^6 m, and g at its surface is about 9.8 m/s^2. Using G = 6.673 Who first measured the gravitational constant G experimentally, and when?Why does the moon not trace a perfectly smooth circle around the sun?Before Kepler, Copernicus, and Galileo, the Ptolemaic model placed which body at the cente