Everything about Free Fall totally explained
Free fall is motion with no
acceleration other than that provided by
gravity. Since this definition doesn't specify
velocity, it also applies to objects initially moving upward. Although the definition specifically excludes all other forces such as
aerodynamic drag, in nontechnical usage falling through an
atmosphere is also referred to as free fall.
Examples
Examples of objects in free fall include:
- A spacecraft (in space) with its rockets off (for example in a continuous orbit, or going up for some minutes, and then down)
- The Moon orbiting around the Earth.
- An object dropped in a drop tower for a physics demonstration at NASA's Zero-G Research Facility
Examples of objects not in free fall:
- Standing on the ground: the gravitational acceleration is counteracted by the normal force from the ground.
- Flying horizontally in an airplane: the wings' lift is also providing an acceleration.
- Jumping from an airplane: there's a resistance force provided by the atmosphere.
On Earth
Near sea level, an object in free fall in a vacuum will accelerate at approximately 9.81 m/s
, regardless of its mass. With air resistance acting upon an object that has been dropped, the object will eventually reach a
terminal velocity (around 120 mph (200 km/h) for a human body). Terminal velocity depends on many factors including mass, drag coefficient, and relative surface area, and will only be achieved if the fall is from sufficient altitude.
Free fall in Newtonian Mechanics
Without air resistance
»
Surviving falls
JAT stewardess
Vesna Vulović survived a fall of 33,000 feet (over 10,000 meters) on January 26, 1972 when she was thrown from
JAT Flight 364, after the plane
Croatian terrorists
Ustashes downed with explosives over
Srbská Kamenice in former
Czechoslovakia (now
Czech Republic).
Serbian stewardess suffered a broken skull, three broken vertebratae bones, one crushed completely, and was in a coma for 27 days. In an interview, according to the man who found her, "he told me that 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 with Hitler's troops as a medic during the War. He was German. 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
I.M.Chisov all fell at least 5,500 meters and survived.
Freefall isn't to be confused with individuals who survive instances of various degrees of
controlled flight into terrain. Such impact forces affecting these instances of survival, differ from the forces which are characterized by free fall.
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.
Record 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 80,380 ft (24,500 m) from an altitude of 83,523 ft (25,457 m) near the city of
Saratov, Russia on
November 1,
1962. Andreev didn't use a
drogue chute during his jump.
Attempts
Michel Fournier, 64, will attempt on
May 24, 2008 to break
Joe Kittinger's 1960 records by Le Grand Saut (The Great Leap) from the
Saskatchewan plains. He will climb into the pressurized capsule or
gondola of the 650-foot balloon, and make a 2-hour journey to 130,000 feet or almost 25 miles. Wearing only a special space suit and a
parachute, he'll plunge down in a mere 15 minutes. If successful, he'll fall longer, farther and faster than anyone in history, breaking the 50 years sound barrier and 4 records: fastest
free fall, longest free fall, highest altitude for a human balloon flight and highest parachute jump. Fournier attempted his stunt but failed twice, amid 8,000 jumps and setting a French record from an altitude of more than 39,000 feet, his highest jump to date.
Accidental free fall
On June 6, 1989, a NASA stratospheric balloon launched from
Columbia Scientific Balloon Facility (then known as National Scientific Balloon Facility) in
Palestine,
Texas, suffered an uncommanded payload release while flying at 120,000 feet over a thunderstorm near
Graham, Texas. Months after the accident, a post-flight investigation concluded that a
lightning bolt traveling up from the clouds provoked the incident. The payload hit the ground at an estimated speed of 700 mph (1,100 kph). No one was harmed, but the incident forced the agency to change its policy, forbidding the flying of balloons over thunderstorms.
Free-falling aircraft and microgravity
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