When an object falls, its velocity increases due to the force of gravity. Here's a breakdown:

* Gravity: Earth exerts a force of gravity on all objects near its surface. This force pulls the object downwards.

* Acceleration: This gravitational force causes the object to accelerate, meaning its velocity increases over time.

* Constant Acceleration: The acceleration due to gravity is nearly constant near the Earth's surface (approximately 9.8 m/s²). This means the velocity increases by 9.8 meters per second every second the object falls.

Important Note: This assumes there's no air resistance. In reality, air resistance opposes the object's motion, slowing it down as it falls. The object eventually reaches a terminal velocity, where the force of air resistance balances the force of gravity, and the object stops accelerating.