Free-fall

Free-fall or free fall in the strict sense is the condition of acceleration which is due only to gravity. In other words, the objects undergoing freefall experience only one force: their own weight.

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Examples include:

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• a spacecraft with the rockets off
• the Moon's trajectory around the Earth, or the Earth's orbit around the Sun.

as opposed to the cases where other forces are acting, including:

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• standing on the ground, sitting in a chair on the ground, etc. (gravity is cancelled by the reaction force of the ground)
• flying in a plane (gravity is cancelled by the lift the wings provide) - see below for special trajectories which form an exception
• atmospheric reentry, landing on a parachute: gravity is opposed by atmospheric drag
• during an orbital maneuver in a spacecraft: the rocket provides thrust

More generally, freefall is the condition of acceleration which is due only to gravity and air friction: in parachuting, freefall (skydiving) refers to the act of falling and delaying the opening of a parachute. Freeflying is skydiving in other body positions than the more standard belly flying.

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With air friction acting upon an object that has been dropped the object will eventually reach terminal velocity (around 120 miles/hour for a human body flying in the belly-down arched position; terminal velocity depends on many factors including mass, drag coefficient, and relative surface area) if the fall is from sufficient altitude (2,000 ft) and also otherwise uninterrupted.

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Free-fall: People surviving free fall ►



 

Gravity: :For other senses of the words gravity and gravitation, see gravity (disambiguation)....

Force: In physics, a force is an external cause responsible for any change of a physical system. For instance, a person holding a dog by a rope is experiencing the force applied by the rope on his hand, and the cause for its pulling forward is the force exercised by the rope. The kinetic expression of th...

Weight: :See also weight function....




Free-fall related Images and Photos (experimental)

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