The key is that acceleration due to gravity is independent of mass.
Here's the breakdown:
* Gravity's Force: The force of gravity between two objects (like the Earth and the brick/sponge) depends on their masses *and* the distance between them. A more massive object has a greater gravitational force acting on it.
* Newton's Second Law: Newton's Second Law of Motion states that force equals mass times acceleration (F = ma).
* Combining the Concepts: While a heavier object experiences a stronger gravitational force, it also has a greater mass. These two factors balance out! The increased force on the heavier object is exactly compensated by its larger inertia (resistance to change in motion), resulting in the same acceleration.
In simpler terms:
Imagine dropping a brick and a sponge from the same height.
* The brick feels a stronger pull from gravity (due to its greater mass).
* However, the brick also resists moving more than the sponge due to its greater mass.
* These two effects perfectly cancel out, causing both objects to fall at the same rate (ignoring air resistance).
Important Note: This is only true in a vacuum. Air resistance can significantly affect the speed at which different objects fall. A brick will fall faster than a sponge in air because the brick has a smaller surface area relative to its mass, leading to less air resistance.
