Final answer:
The gravitational force that a person exerts on Earth is equal to the force Earth exerts on the person, despite Earth's much greater mass. The apparent discrepancy arises from Earth's immense mass, which results in a very small acceleration of Earth, but the forces themselves are identical in magnitude due to Newton's third law of motion.
Step-by-step explanation:
The question pertains to Newton's third law of motion, which applies to the gravitational force between two masses. In this case, the two masses are a person and the Earth. Newton's third law of motion states that for every action, there is an equal and opposite reaction. This implies that the gravitational force that the Earth exerts on a person is exactly equal to the force the person exerts on the Earth. However, since Earth's mass is vastly greater than that of a person, the acceleration experienced by the Earth due to this force is imperceptibly small, making it seem as if the person's force on Earth is negligible. In reality, gravitational attraction is a fundamental interaction that acts equally on both masses regardless of their size.
It is key to understand that gravitational force is significant on a large scale—such as between the Earth and a person—but not noticeable at the level of individual particles, due to their near electrical neutrality. If the Earth had only one-third of its present mass, a person's weight—representing the gravitational pull on them—would be reduced to one-third because weight is directly proportional to the mass causing the gravitational pull. Consequently, a change in a celestial body's mass or a person's mass would directly affect the gravitational force experienced.