Gravitational potential energy: Two planets having equal masses are in circular orbit around a star. Planet A has a smaller orbital radius than planet B. Which statement is true?
A) Planet A has more kinetic energy, less potential energy, and less mechanical energy (potential plus kinetic) than planet B.
B) Planet A has more kinetic energy, more potential energy, and more mechanical energy (potential plus kinetic) than planet B.
C) Planet A has more kinetic energy, less potential energy, and more mechanical energy (potential plus kinetic) than planet B.
D) Planet A and planet B have the same amount of mechanical energy (potential plus kinetic).

Question

Quizplus · Accepted Answer

Planet A has a smaller orbital radius, so it has a greater gravitational potential energy than planet B. Since the planets have equal masses and are in circular orbits, they have equal kinetic energies. Therefore, planet A has less kinetic energy, more potential energy, and more mechanical energy (potential plus kinetic) than planet B.

Gravitational Potential Energy: Two Planets Having Equal Masses Are in Circular