In Newtonian physics, free fall is any motion of a body where its weight is the only force acting upon it. In the context of general relativity, where gravitation is reduced to a space-time curvature, a body in free fall has no force acting on it and moves along a geodesic. The present article only concerns itself with free fall in the Newtonian domain.
An object in the technical sense of free fall may not necessarily be falling down in the usual sense of the term. An object moving upwards would not normally be considered to be falling, but if it is subject to the force of gravity only, it is said to be in free fall. The moon is thus in free fall.
In a uniform gravitational field, in the absence of any other forces, gravitation acts on each part of the body equally and this is weightlessness, a condition that also occurs when the gravitational field is zero (such as when far away from any gravitating body). A body in free fall experiences "0 g".
The term "free fall" is often used more loosely than in the strict sense defined above. Thus, falling through an atmosphere without a deployed parachute, or lifting device, is also often referred to as free fall. The aerodynamic drag forces in such situations prevent them from producing full weightlessness, and thus a skydiver's "free fall" after reaching terminal velocity produces the sensation of the body's weight being supported on a cushion of air.In the Western world prior to the Sixteenth Century, it was generally assumed that the speed of a falling body would be proportional to its weight—that is, a 10 kg object was expected to fall ten times faster than an otherwise identical 1 kg object through the same medium. The ancient Greek philosopher Aristotle (384–322 BC) discussed falling objects in what was perhaps the first book on mechanics.
The Italian scientist Galileo Galilei (1564–1642) subjected the Aristotelian theories to experimentation and careful observation. He then combined the results of these experiments with mathematical analysis in an unprecedented way.
In a tale that may be apocryphal, Galileo (or an assistant, more likely) dropped two objects of unequal mass from the Leaning Tower of Pisa. Given the speed at which such a fall would occur, it is doubtful that Galileo could have extracted much information from this experiment. Most of his observations of falling bodies were really of bodies rolling down ramps. This slowed things down enough to the point where he was able to measure the time intervals with water clocks and his own pulse (stopwatches having not yet been invented). This he repeated "a full hundred times" until he had achieved "an accuracy such that the deviation between two observations never exceeded one-tenth of a pulse beat."In 1914, while doing demonstrations for the U.S. Army, a parachute pioneer named Tiny Broadwick deployed her chute manually, thus becoming the first person to jump free-fall.
According to the Guinness Book of Records, Eugene Andreev (USSR) holds the official FAI record for the longest free-fall parachute jump after falling for 24,500 metres (80,400 ft) from an altitude of 25,458 metres (83,524 ft) near the city of Saratov, Russia on November 1, 1962. Although later on jumpers would ascend higher altitudes, Andreev's record was set without the use of a drogue chute during the jump and therefore remains the longest genuine free fall record.
During the late 1950s, Captain Joseph Kittinger of the United States was assigned to the Aerospace Medical Research Laboratories at Wright-Patterson AFB in Dayton, Ohio. For Project Excelsior (meaning "ever upward", a name given to the project by Colonel John Stapp), as part of research into high altitude bailout, he made a series of three parachute jumps wearing a pressurized suit, from a helium balloon with an open gondola.
The first, from 89,000 feet (23,290 m) in November 1959 was a near tragedy when an equipment malfunction caused him to lose consciousness, but the automatic parachute saved him (he went into a flat spin at a rotational velocity of 120 rpm; the g-force at his extremities was calculated to be over 22 times that of gravity, setting another record). Three weeks later he jumped again from 74,700 feet (22,770 m). For that return jump Kittinger was awarded the A. Leo Stevens parachute medal.
On August 16, 1960 he made the final jump from the Excelsior III at 102,800 feet (31,330 m). Towing a small drogue chute for stabilization, he fell for 4 minutes and 36 seconds reaching a maximum speed of 614 mph (988 km/h)[4] before opening his parachute at 14,000 feet (4,270 m). Pressurization for his right glove malfunctioned during the ascent, and his right hand swelled to twice its normal size.[5] He set records for highest balloon ascent, highest parachute jump, longest drogue-fall (4 min), and fastest speed by a human through the atmosphere.
The jumps were made in a "rocking-chair" position, descending on his back, rather than the usual arch familiar to skydivers, because he was wearing a 60-lb "kit" on his behind and his pressure suit naturally formed that shape when inflated, a shape appropriate for sitting in an airplane cockpit.
For the series of jumps, Kittinger was decorated with an oak leaf cluster to his Distinguished Flying Cross and awarded the Harmon Trophy by President Dwight Eisenhower.
In 2012, the Red Bull Stratos mission took place. On October 14, 2012, Felix Baumgartner broke the records previously set by Kittinger for the highest free fall, the highest manned helium balloon flight, and the fastest free fall; he jumped from 128,100 feet (39,045 m), reaching 833.9 mph (1342 km/h) - Mach 1.24. Kittinger was a member of the mission control and helped design the capsule and suit that Baumgartner ascended and jumped in.
On October 24, 2014, Alan Eustace broke the record previously set by Baumgartner for the highest free fall. He jumped from a height of 135,908 feet (41,425 m)The severity of injury increases with the height of a free fall, but also depends on body and surface features and the manner that the body impacts on to the surface. The chance of surviving increases if landing on a surface of high deformity, such as snow.
Overall, the height at which 50% of children die from a fall is between four and five storey heights above the ground.
JAT stewardess Vesna Vulović survived a fall of 10,000 metres (33,000 ft)[10] on January 26, 1972 when she was aboard JAT Flight 367. The plane was brought down by explosives over Srbská Kamenice in the former Czechoslovakia (now the Czech Republic). The Serbian stewardess suffered a broken skull, three broken vertebrae (one crushed completely), and was in a coma for 27 days. In an interview, she commented that, according to the man who found her, "…I was in the middle part of the plane. I was found with my head down and my colleague on top of me. One part of my body with my leg was in the plane and my head was out of the plane. A catering trolley was pinned against my spine and kept me in the plane. The man who found me, says I was very lucky. He was in the German Army as a medic during World War Two. He knew how to treat me at the site of the accident."
In World War II there were several reports of military aircrew surviving long falls: Nick Alkemade, Alan Magee, and Ivan Chisov all fell at least 5,500 metres (18,000 ft) and survived.
It was reported that two of the victims of the Lockerbie bombing survived for a brief period after hitting the ground (with the forward nose section fuselage in freefall mode), but died from their injuries before help arrived.
Juliane Koepcke survived a long free fall resulting from the December 24, 1971, crash of LANSA Flight 508 (a LANSA Lockheed Electra OB-R-941 commercial airliner) in the Peruvian rainforest. The airplane was struck by lightning during a severe thunderstorm and exploded in mid air, disintegrating two miles up. Köpcke, who was 17 years old at the time, fell to earth still strapped into her seat. The German Peruvian teenager survived the fall with only a broken collarbone, a gash to her right arm, and her right eye swollen shut.
In October 1985, 11-year-old Cindy Mosey survived a free fall of between three and five hundred feet into the sea from an Air Albatross Cessna 402B, which disintegrated in mid-flight after hitting a high voltage electricity transmission line spanning the Tory Channel in New Zealand's Marlborough Sounds. She was the sole survivor of the accident, which killed eight people including all of her family. She went on to a successful career as an international kite-surfer.
As an example of 'freefall survival' that was not as extreme as sometimes reported in the press, a skydiver from Staffordshire was said to have plunged 6,000 metres without a parachute in Russia and survived. James Boole said that he was supposed to have been given a signal by another skydiver to open his parachute, but it came two seconds too late. Boole, who was filming the other skydiver for a television documentary, landed on snow-covered rocks and suffered a broken back and rib. While he was lucky to survive, this was not a case of true freefall survival, because he was flying a wingsuit, greatly decreasing his vertical speed. This was over descending terrain with deep snow cover, and he impacted while his parachute was beginning to deploy. Over the years, other skydivers have survived accidents where the press has reported that no parachute was open, yet they were actually being slowed by a small area of tangled parachute. They might still be very lucky to survive, but an impact at 80 mph (about 129 kph) is much less severe than the 120 mph (about 193 kph) that might occur in normal freefall.
A falling person will reach terminal velocity after about 12 seconds, falling some 450 m (about 1,500 ft) in that time. That person will not then fall any faster, so it makes no difference what distance they fall if it is more than 450 m—they will still reach the ground at the same speed.The speeds reached by Kittinger, Baumgartner and Eustace were faster due to the thinner atmosphere at higher altitudes. Terminal velocity depends on air resistance, so terminal velocity increases as air resistance decreases.
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