## Forces which may cause death

A human body experiencing a sufficient acceleration for a sufficient length of time will experience a fatal force if it causes the forces holding together life-sustaining biological systems to be overcome. However, the magnitude of this acceleration is typically larger than one would expect, if the force is applied equally to the whole of the body. It may take an acceleration of more than seventy-five times the acceleration due to gravity (75g) to kill an adult male. But if the acceleration is sustained for several seconds, death can result from only four to ten g, as the brain is deprived of oxygen.1 John Stapp survived this and many other tests, demonstrating that a person can withstand acceleration up to 45g if he or she is properly restrained.2

The force necessary to accelerate a 75kg person at 4g is nearly 3000 Newtons (N). However, death may be caused by considerably less force. If the breaking stress of flesh is a given value K in N/m2 such that... 3...where F is the force applied to a given area A, then we can see that the relationship between F and K is proportional, so that as the area the force is being applied to is decreased, then so is the force necessary to rend flesh. From this, we can see that an arbitrarily small force may cause death, provided that it is being applied with a blade that is arbitrarily sharp.