A student studies the table to identify the factor that determines a planet's orbital velocity, which is the speed at which a planet orbits around a central body. Based on the table, which of the following can the student reasonably conclude?

Question

A.

Distance from the Sun determines a planet's orbital velocity; planets closer to the Sun have a faster orbital velocity.
B.

Rotation period determines a planet's orbital velocity; planets with shorter days have a slower orbital velocity.
C.

Surface gravity of a planet determines its orbital velocity; planets with less gravity have a slower orbital velocity.
D.

Average density determines a planet's orbital velocity; planets with a lower density have a faster orbital velocity.

Answer 1

The correct answer based on the gravitational principles governing orbital velocity is:

A. Distance from the Sun determines a planet's orbital velocity; planets closer to the Sun have a faster orbital velocity.

This conclusion aligns with Kepler's laws of planetary motion and the law of universal gravitation, which states that the gravitational force (and thus the orbital velocity) between two bodies is influenced by the distance between them. Planets that are closer to the Sun experience a stronger gravitational pull, which allows them to have a faster orbital velocity compared to those that are farther away.