The following table shows the distance from the sun of some unknown planets of equal mass.
Distance from Sun
Planet Distance from Sun
Y 1 AU
Z 0.39 AU
Which of the following best explains which planet revolves at a slower speed?
Group of answer choices
Planet Y, because the sun pulls it with a greater force
Planet Z, because the sun pulls it with a greater force
Planet Y, because the gravitational force is weakened by distance
Planet Z, because the gravitational force is strengthened by distance
The correct answer is:
Planet Y, because the gravitational force is weakened by distance.
According to Newton's law of universal gravitation, the gravitational force between two objects is inversely proportional to the square of the distance between them. Therefore, as the distance from the sun increases, the gravitational force between the planet and the sun decreases. Hence, Planet Y, which is further from the sun than Planet Z, will experience a weaker gravitational force and will revolve at a slower speed.