Freefall 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.

Examples include:

• 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:

• 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, the condition "not experiencing air friction" is dropped: 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.

With air friction acting upon an object in freefall the object will eventually reach terminal velocity if the fall is from sufficient altitude and also otherwise uninterrupted.

At least three people have survived free falls of around 20,000ft without a parachute. All three were airmen in the Second World War; Lt. I.M. Chisov was a Russian bomber, Sgt. Alan Magee an American gunner on a B-17, and Sgt. Nicholas Alkemade a British gunner on a Lancaster bomber. It is estimated that a person free falling horizontally, reaches a maximum velocity of around 120 mph after a fall of just 2,000ft, so the additional 18,000ft doesn't make these falls that much more dangerous, apart from the lack of oxygen at high altitude. All three men lost conciousness during their falls, and two of them landed on terrain covered in deep snow, which was probably a signficant factor in the survivability of the falls.

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Freefall is a popular webcomic written and drawn by Mark Stanley. It is a humorous science fiction story cataloguing the misadventures of the starship Savage Chicken and its crew: Sam, a lovable two-timing con artist; Helix, a childlike robot; and Florence, a genetically engineered "Bowman's Wolf" (DOGGY!).

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Free Fall is a novel by William G. Golding.

References

• Free fall accidents (http://members.aol.com/MercStG/FFAccPage1.html) and parachute history (http://www.parachutehistory.com/other/bonusday.html)

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