Terminal velocity is the maximum velocity reached by a falling object when the drag force acting on it equals the force of gravity. When an object is dropped from a sufficient height, it initially accelerates due to the force of gravity. However, as it accelerates, the drag force (air resistance) acting on the object also increases.
At some point, the drag force becomes equal in magnitude to the force of gravity pulling the object downward. At this stage, the net force on the object becomes zero, resulting in a constant velocity. This constant velocity is known as the terminal velocity.
The terminal velocity of an object depends on several factors, including the object's mass, size, shape, and the density of the medium through which it is falling (usually air). Larger, more massive objects tend to have higher terminal velocities than smaller, less massive objects. Additionally, objects with streamlined shapes experience less air resistance and, therefore, reach higher terminal velocities compared to objects with irregular shapes.
The concept of terminal velocity arises because of the relationship between gravitational force and drag force. Initially, when an object is dropped, the force of gravity is greater than the drag force, resulting in acceleration. As the object accelerates, the drag force increases due to the object's velocity, eventually matching the force of gravity. This equilibrium between the two forces leads to a constant velocity and no further acceleration, which is the terminal velocity.
It's worth noting that terminal velocity is specific to the medium through which the object is falling. For example, an object's terminal velocity in air would be different from its terminal velocity in water due to differences in air and water density and viscosity.