Forces and Motion: Terminal Velocity

Terminal velocity is a concept in physics concerning the maximum constant speed that a freely falling object eventually reaches when the resistance of the medium through which it is falling prevents further acceleration.
It occurs when the force of gravity pulling an object down is equal to the air resistance pushing it up, balancing out the forces.
Initially, when an object falls, gravitational force is greater than air resistance, and the object speeds up. This is the phase of acceleration.
As the speed of the object increases, the air resistance acting against it also increases.
When the increasing air resistance exactly equals the force of gravity pulling the object down, no further acceleration occurs.
At this point, the object ceases to accelerate and continues to fall at a steady speed. This speed is known as the terminal velocity.
Terminal velocity varies from object to object depending on its shape, density, and surface area. For instance, a feather will have a much lower terminal velocity than a stone of the same size due to the larger air resistance it experiences.
The terminal velocity of a human body in freefall is about 53 m/s or 191 km/h (120 mph), but with a streamlined body position like those used by skydivers, it can be increased to around 90 m/s (320 km/h or 200 mph).
Parachutes work by increasing air resistance dramatically, reducing the skydiver’s terminal velocity to a safe landing speed.
Understanding terminal velocity is crucial in a range of fields, from aeronautical engineering to biology, studying bird flight for example.
Problems based on terminal velocity often involve understanding and applying the principles of net force, equilibrium and freely falling bodies.