Max Accel for Pressure in Heart to Reach Brain

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The discussion focuses on determining the maximum acceleration in an aircraft that prevents the heart from pumping blood to the brain, given specific parameters such as the height of the head above the heart and the pressure exerted by the heart. The equations of motion and pressure relationships are explored, particularly how the upward acceleration affects blood pressure at the foot and heart. The pressure at the heart is debated, with uncertainty about whether it remains at 100 mmHg under these conditions. A suggestion is made to simplify the problem by substituting variables to find a solution. The conversation emphasizes the importance of understanding the relationship between acceleration and blood pressure in this scenario.
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A man is standing up in aircraft that has a constant accerelation upward. Find the maximum accerelation that heart can't pump blood to brain. Head is 50cm above the heart. Pheart=100mmHg
ΣF=ma
Fn-mg=ma
Fn=m(g+a)=ρ(blood)V(g+a)
Pfoot=ρ(blood)H(g+a)
Pheart=Pfoot-ρ(blood)(H-0.5)(g+a)
I don't know in this situation Pheart=100mmHg or not
 
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It's a lot simpler than you think.

Pfoot=ρ(blood)H(g+a).....(1)
Pheart=Pfoot-ρ(blood)(H-0.5)(g+a)......(2)

The hard way to solve this is to expand (2) and substitute (1) into (2) to eliminate Pfoot and H.

Try it and the answer might suggest an easier way.
 
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aopaop03 said:
I don't know in this situation Pheart=100mmHg or not

Yes. That's the pressure the heart can create.
 
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