The Physics
An encyclopedia of scientific essays

Acceleration That Would Kill a Human

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Michael Behar. "Defying Gravity." Scientific American. vol. 286, no. 3 (March 2002): 32-4. "Planes today are so fast and nimble that standard evasive maneuvers can add nine times the weight of gravity, or nine g's, to the mass of a pilot's body. That amount of force causes fatigue, blackouts, even death as gravity drives blood and oxygen from the brain, lungs and heart." 9 g
"Aerospace Medicine." Microsoft Encarta Encyclopedia 99. "If a force of 4 to 6g is sustained for more than a few seconds, the resulting symptoms range from blackouts to total death." 4–6 g
Could a seat belt have saved Diana? CNN. 5 September 1997. "The acceleration that would have been experienced by the chest would have been about 70 times the force of gravity (70 g's), or about seven times what a fighter pilot experiences. The head would have experienced acceleration about 100 times the force of gravity." 70–100 g
Reed, Kevin. Re: In a vacuum, can an ant survive a fall that would kill a human? MadSci Network. 4 November 2003. "The NHTSA standard for a sudden impact acceleration on a human that would cause severe injury or death is 75 g's for a "50th percentile male", 65 g's for a "50th percentile female", and 50 g's for a "50th percentile child". These figures assume the human is taking the impact on the chest/stomach, the back, sides or the head. The average value is about 65 g's, so I used that for the fatal impact acceleration on a human being." 50–75 g

The change of velocity of any object is said to be accelerating. Acceleration is known as the rate of change of velocity with time. The changing direction, increasing speed, decreasing speed of an object are all factors of acceleration. That's because velocity is a vector quantity, one which acceleration depends upon. Velocity has both magnitude and direction. The SI unit for acceleration is m/s2. Some popular examples of acceleration could be a falling apple (accelerating), a car stopping (decelerating), or direction of motion changing.

In general, high velocity doesn't produce harmful injuries. But what is dangerous is the high acceleration or deceleration given at a certain time interval. The common term "g-force" is a measure of acceleration and is not a measure of force. Everything is said to feel normal at 1 g, twice as heavy at 2 g, and weightless at 0 g. I'd like to discuss some of the factors which play a key role in which may cause the death of human due to high acceleration.

First of all, the human body is composed of different organs each organ containing its own different given density. When placing a human under high acceleration the brain, lungs, ribs (any bones), and women's breast (tissue fat) all affect the death of the human. Its reason is that each different body part has a higher density than another which causes certain organs to undergo more g-force than other organs.

Pilots, roller coaster rides, and car crashes are sufficient examples of g-force. Roller coasters give humans a thrill ride. They undergo forces of maximum up to 3 to 4 g's for brief periods of time. Pilots on the other hand are trained to undergo accelerations of 9 g's to pull quick maneuvers during flight for less than a second. If a force of 4 to 6 g's is held for more than a few seconds, the results could be devastating; such as blackouts to death. The devastating car crash of Princess Diana of Wales in 1997 was estimated to range somewhere between 70–100 g's. This accident was intense enough to pull the pulmonary artery from her heart. It's important to understand that velocity alone plays no role in the symptoms of injuries of a human.

Yuriy Rafailov -- 2004