* Gravity: The Earth exerts a gravitational force on all objects near its surface. This force pulls objects towards the center of the Earth.
* Acceleration: Acceleration is the rate of change of velocity. When an object falls freely, its velocity increases as it falls, meaning it's accelerating.
* Constant Acceleration: The acceleration due to gravity near the Earth's surface is roughly constant, approximately 9.8 m/s². This means that for every second an object falls, its downward velocity increases by 9.8 meters per second.
Why is the acceleration constant?
The force of gravity is proportional to the mass of the object. A more massive object experiences a stronger gravitational pull. However, the acceleration due to gravity is independent of the object's mass. This is because a more massive object also has more inertia (resistance to change in motion). The increased force of gravity is exactly balanced by the increased inertia, resulting in a constant acceleration for all objects in free fall.
Important Note: This explanation assumes ideal conditions. In reality, air resistance (drag) can affect the acceleration of falling objects. The force of drag increases with the object's speed, eventually counteracting the acceleration due to gravity and leading to a terminal velocity (constant speed).
