A ball falling toward the earth's surface accelerates at 9.8 meters per second squared (
A ball falling toward the earth increases its velocity by 9.8 meters per second every second until it strikes the ground. However, this does not take air resistance into account.
Air resistance will affect the acceleration of the ball toward the earth based upon the density of the ball. A steel shot put will accelerate faster than a softball, not because the steel shot put has more mass, but because it is more dense relative to the air around it.
If it were not for air resistance, all objects would accelerate toward the ground at the exact same rate. This is because of Newton's Second Law: "Force equals mass times acceleration" as well as his Law of Universal Gravitation. Although a more massive object (such as a steel shot put) shares a greater attraction with the earth, it also requires greater force to accelerate more massive objects. Therefore, the shared attraction between the heavier object and the earth, and the greater amount of force required to accelerate a heavier object toward the earth cancel each other out exactly.
The figure 9.8 m/s/s represents Earth's gravitational pull based upon the mass of the earth. On other planets or celestial bodies, this figure will vary based upon the mass of the planet.