Ask A Scientist© Physics Archive

Question:  What is the greatest amount of g forces experienced?
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Answer 1:  I believe that 9 g's is about the maximum for human beings..
at 9g's, most will black out after a few tens of seconds.
Since most modern jet fighters can pull at least 9 Gs in a tight
turn, this is a serious problem for the Air Force.
The early manned-space flight program used to launch astronauts
at 9 Gs, the Mercury, Gemini, and Apollo programs.  The space
shuttle is launched at a "comfortable" 3 Gs.
John Hawley
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Answer 2:  Actually, one can experience much higher accelerations for
very short periods of time with little injury - I have heard
of up to 100 g's for a fraction of a second.  Your body can
effectively lower the force by compressing a bit too, so actually
no acceleration really acts instantaneously.
Arthur Smith
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