alleryStart learning →Earth orbits the sun at 1.496 x 10^8 km, taking one year. Neptune orbits at 4.490 x 10^9 km. About how many Earth years does Neptune take to complete one orbit?
A10 years
B30 years
C160 years
D900 years
Answer & Solution
Correct answer: C. 160 years
1. By Kepler's third law, T_Neptune = T_Earth x (r_Neptune / r_Earth)^1.5.
2. The ratio of distances is 4.490 x 10^9 / 1.496 x 10^8 = 30.0.
3. T_Neptune = (1 year) x (30.0)^1.5 = 1 x 164 years, which is closest to 160 years.
_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 xA moon's orbital focal point sits 50,000 km from the center of its elliptical orbit, and tMercury 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