Physics - Human Tolerance to g-forces, acceleration limits, physiology

In summary, the human body's tolerance to extreme g-forces is limited by the lowered systolic blood pressure in the brain, which leads to decreased perfusion of cells and can result in loss of consciousness and vision. This phenomenon occurs around 10g and is caused by a lack of oxygen and nutrients reaching the brain and eye cells.
  • #1
Albertgauss
Gold Member
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Hi all,

Does anyone know what physics limits human tolerance to extreme g-forces? I know the average human can take g-forces 5-7 g, and a fighter pilot, with training and a G-suit can maybe get up to 12 g. And people can survive g-forces higher than this for a very short time. I know all the effects of extreme g-forces; eyeballs popping out, dimming vision etc, but why do these effects occur, and why do they occur around 10g from a physiological standpoint? What happens in the cells and atoms of a human being that falls apart when humans accelerate a lot? What is the weakest part of the human body at the organ, cell, tissue level that breaks up when the acceleration is too large for too long (corresponding to large forces)? Any articles are appreciated if anyone knows of any.
 
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  • #2
Albertgauss said:
Hi all,

Does anyone know what physics limits human tolerance to extreme g-forces? I know the average human can take g-forces 5-7 g, and a fighter pilot, with training and a G-suit can maybe get up to 12 g. And people can survive g-forces higher than this for a very short time. I know all the effects of extreme g-forces; eyeballs popping out, dimming vision etc, but why do these effects occur, and why do they occur around 10g from a physiological standpoint? What happens in the cells and atoms of a human being that falls apart when humans accelerate a lot? What is the weakest part of the human body at the organ, cell, tissue level that breaks up when the acceleration is too large for too long (corresponding to large forces)? Any articles are appreciated if anyone knows of any.

The physics is about the lowered systolic blood pressure in the brain/head. The physiology is about the lowered perfusion of the cells in the brain (and eyes) from the lowered systolic blood pressure in the head. Nothing to do with eyeballs popping out. The lowered perfusion of cells in the brain (and eyes) causes the LOC (loss of consciousness) and loss of vision.
 

1. What is the maximum g-force a human can withstand?

The maximum g-force a human can withstand depends on various factors such as the direction of the force, duration, and individual tolerance. However, on average, a person can withstand up to 5g for a short period of time without experiencing any serious negative effects.

2. How does acceleration affect the human body?

Acceleration can affect the human body in several ways, depending on the direction and duration of the acceleration. It can cause motion sickness, disorientation, loss of consciousness, and even serious injuries if the force is too strong or lasts for a long time.

3. Can training increase a person's tolerance to g-forces?

Yes, training can increase a person's tolerance to g-forces. Pilots, astronauts, and other professionals who are regularly exposed to high levels of g-forces undergo specialized training to improve their body's ability to withstand and adapt to these forces.

4. How does the body compensate for high g-forces?

The body has various physiological mechanisms to compensate for high g-forces. These include the activation of the autonomic nervous system, increased blood flow to the brain, and muscle contractions to maintain blood pressure and prevent blood from pooling in the lower extremities.

5. What are the potential long-term effects of exposure to high g-forces?

Exposure to high g-forces for extended periods can have negative effects on the body, such as damage to the cardiovascular system, vision problems, and bone and muscle loss. It can also lead to chronic health conditions, including heart disease and osteoporosis.

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