# Terminal velocity

Terminal velocity is the speed when a falling object is no longer getting faster. Velocity means how fast something is changing position in both speed and direction.

Terminal velocity happens at the moment in time that the force, because of gravity, called weight, is the same as the opposite force of air resistance or friction. In other words, terminal velocity is the point at which the velocity (speed of change of the falling object) is no longer getting greater. The gravitational force minus the force of drag (or air resistance) equals zero.[1]

An object continues to fall steadily until air resistance becomes so great that it equals with the pull of gravity and the object can fall no faster.

## Example

The terminal velocity of a skydiver in a belly-to-earth (i.e., face down) free-fall position is about 195 km/h (122 mph or 54 m/s).[2] This velocity is the limit of the acceleration process. The forces on the body balance each other more and more closely as the terminal velocity is approached. In this example, a speed of 50% of terminal velocity is reached after only about 3 seconds, while it takes 8 seconds to reach 90%, 15 seconds to reach 99% and so on.

Higher speeds are achieved if the skydiver pulls in his or her limbs (see also freeflying). In this case, the terminal velocity increases to about 320 km/h (200 mph or 90 m/s),[2] which is almost the terminal velocity of the Peregrine Falcon diving down on its prey.[3]

## References

1. Mathias Svensson (2012). "The influence of weight on terminal velocity". Copenhagen University. Retrieved 21 August 2014.
2. Huang, Jian (1999). "Speed of a skydiver (terminal velocity)". The Physics Factbook. Glenn Elert, Midwood High School, Brooklyn College.
3. "All about the peregrine falcon (archived)". U.S. Fish and Wildlife Service. 2007-12-20.