Final answer:
The force exerted on Earth by a falling apple is equal and opposite to the force exerted on the apple, as per Newton's third law. However, due to Earth's significantly greater mass, the acceleration experienced by Earth is imperceptible compared to the noticeable acceleration of the apple towards Earth.
Step-by-step explanation:
A dropped apple falls toward Earth due to the gravitational force between it and Earth. According to Newton's third law, every action has an equal and opposite reaction. Therefore, compared to the downward force on the apple, the force on Earth is equal in magnitude but opposite in direction. This means that while the apple experiences a force pulling it towards Earth (its weight), Earth experiences a force of the same strength pulling it towards the apple.
The universal law of gravitation demonstrates that gravitational forces are mutual and that the gravitational force is proportional to the masses involved and inversely proportional to the square of the distance between their centers. Despite this, the effect of this force on Earth is negligible compared to the force on the apple due to the vast difference in mass. Earth's mass is so great that the acceleration it experiences from the pull of the apple is infinitesimally small, whereas the apple's smaller mass allows for a noticeable acceleration towards Earth.