# Forces and Motion: Terminal Velocity

## 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.