Submitted by [deleted] t3_z72gte in explainlikeimfive
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Comments
jensjoy t1_iy4idhc wrote
>but the air underneath you is pushing you up
Not how it works. Pressure comes from the top.
Think when you're diving. The deeper you go the higher the pressure, regardless of how much water is beneath you.
Belisaurius555 t1_iy4tugo wrote
Not what I was saying and not accurate. Change the direction of a barometer and the reading will stay the same. Pressure might increase with depth but the pressure hits you from all directions at once.
Moskau50 t1_iy4pjqa wrote
Pressure is caused by the column height of fluid, but the force that the pressure exerts is omnidirectional (technically, normal to every surface, but assuming a closed, real shape, that becomes omnidirectional). At any given depth, there's no net force of pressure upwards or downwards; assuming a short object, the bottom of the object experiences the same pressure as the top, which means the net force acting on each side is equal.
drafterman t1_iy4dgmy wrote
Because it evolved to do so. All life has evolved on this planet under these conditions so as organisms got larger and more complex, that came with it the necessary internal and external structures to survive in the conditions of its environment.
Don't forget that life came from the sea where the pressure is even greater.
And also don't forget that we aren't sealed tight. We establish an equilibrium with our environment.
[deleted] OP t1_iy4i441 wrote
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[deleted] OP t1_iy4bmcn wrote
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[deleted] OP t1_iy4c32e wrote
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[deleted] OP t1_iy4bgad wrote
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Elongated-towel t1_iy4dalt wrote
Crazy to think all that air only weighs so little. So is it water in the cells creating this outwards pressure?
Belisaurius555 t1_iy4drzr wrote
First off, we were born into it. Honestly, if we didn't have about 14 pounds per square inch pressing down on us we'd suffer and possibly die. That pressure keeps our blood from boiling and oxygen from leeching out of our lungs. Our bodies exert about that much pressure on the air around us and that keeps things balanced.
Second, air pressure hits us from all directions equally. Yes, the air is pushing you down but the air underneath you is pushing you up. You're being pushing forwards, back, left, and right all in about equal measure so the net effect is just a gentle squeeze rather than a crushing force.