Today, I will be discussing on G-force: the acceleration that could kill a man.
Before we delve into the discussion, let's first try to understand what an acceleration is all about, the cause(s), and the factors affecting it. So, in a layman's language, I will say acceleration is the ability of a moving object (e.g man, cars, planes etc) to gain speed. But, according to Physics, acceleration is the rate of change of velocity with respect to time. It is measured in metre per seconds squared. Also from Newton's second law, which states that the force exerted on a body is the product of the mass and its acceleration. Acceleration can be derived from this law by dividing the force exerted on a body with its mass. This short explanation is letting us know that acceleration can only be caused whenever a force is exerted on an object at rest, thereby causing it to move and gain speed.
Aside from the cause of acceleration, there are also some factors affecting acceleration. Some of those factors are the mass of an object, changing of direction, increasing and decreasing speed, the surface area and the acceleration due to gravity (for a case of an object in vertical acceleration). Then, we talk about the effects of acceleration on a human body, in which case the G-force plays a major role. G-force is also called gravitational force.
G-force is a measure of acceleration, but not that of a force. It can't be considered as a fundamental force because it is a type of an acceleration that produces weight and can be measured by an Accelerometer. Basically, it is right to assume that everything on earth is normal at 1g (i.e one acceleration due to gravity which is equivalent to 9.8 metres per seconds squared) but twice as heavier at 2g and weightless at 0g.
Now, I'd like to shed more light on those factors that can cause the death of a man due to high acceleration. Just like we know that our body is composed of many different organs in which those organs have different densities of their own. A normal acceleration won't have any effect on those organs but higher acceleration will. When a man is placed under high acceleration, his organs such as the brain, lungs, bones, and breast all can lead to his death. The reason is that each organ has a higher density than another which causes certain organs to undergo more g-force than the other.
Very notable examples of the effects of g-force can be felt on pilots, roller coaster rides, and car crashes. Although roller coaster rides are very fun to be in and give humans enjoying rides. They undergo forces of up to 3- 4 g for brief periods of time. Pilots, on the other hand, are trained to undergo accelerations of 9 g to pull quick manoeuvres during flight for less than a second. Truly, It may take an acceleration of more than seventy-five times the acceleration due to gravity (75 g) to kill an adult male but if the acceleration is sustained for several seconds at 4-10 g, death can result, as the brain is deprived of oxygen. Taking for instance the gruesome motor accident of Princess Diana of Wales in 1997 was estimated to be in the range of 70-100g and such a great extent of force is capable enough to forcefully remove the artery of her heart.
Furthermore, aside from planes, roller coasters, and cars, the astronauts also do experience the effect of g-force especially during shuttle launches where they usually undergo up to 3g. Some astronauts experienced up to 8g on a Mercury-era Atlas booster rocket, while some are exposed to 7.8g during re-entry.
However, in 1948 an air force physician by the name of John Stapp generated the most extreme g-forces ever to be witnessed on earth. He actually stumbled across it as he was researching on how to make cockpits and pilots safer against the effects of g-forces during plane crashes. He also noticed that majority of the pilots die from the impact of such crashes. So, he developed a rocket-powered, track mounted acceleration sled called the "Gee Whiz" to see how many gs a human being can handle. From Stapp's experiment, (initially using dummies and then later changed to using himself), he noticed that a human body could withstand up to 35 g and survive. In his conclusion, he said that human being is capable of withstanding a massive loads of gs but only for a short time.
Conclusion
Finally, I would conclude by saying that it is not advisable for a human to be exposed to a force more than 35 g for several seconds as that can be very harmful to the body. It can cause lack of blood in the brain which is as a result of oxygen deficiency. This can, in turn, leads to loss of vision, blacking out, loss of consciousness and finally death. Although g-forces are capable of providing fun, they are also a great enemy to the body, because they are capable of killing us within a few seconds if we underestimate them.
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