Atmospheric Pressure Sounds Intense

[AdkinsJr]

Ok, so 1 atm≈101,300 Pa that is 101,300 Newtons per square meter, presumably at sea level. If we look at the force in terms of lbs this is 101,300 N* (.225 lb/1 N)≈22,792 lb.

The pressure per square meter seems pretty intense to me when I thought of it in terms of force. I didn't ask my instructor about this because I didn't notice at first. It's bizarre; how can their be that much force without things being crushed?

At first I thought that it might have something to do with pressure being equal in all directions, so that the forces maybe cancel at some particular depth i.e. a net force is 0. However, that would imply that a planet's atmosphere could not be crushing; we might as well be on Venus.

 

[Dickfore]

Yes, and that's because a 7 mile high column of air weighs down on the Earth's surface.

 

[AdkinsJr]

Yes, and that's because a 7 mile high column of air weighs down on the Earth's surface.

Yeah, I understand why there's so much pressure, what I don't fully understand is why this pressure isn't more crushing than you would intuitively anticipate. Every square meter there's over 20 thousand lbs of force according to that little calculation I did.

I think the forces just largely cancel softening the net force, since pressure is the same in all directions.

 

[Dickfore]

Yeah, I understand why there's so much pressure, what I don't fully understand is why this pressure isn't more crushing than you would intuitively anticipate.

It is very crushing, but it gets compensated, not from all sides, but from the inside and outside. When you try to inhale, your diaphragm reduces the internal pressure a little bit, so that the lungs fill up with air, and, conversely, it increases it a little more when you try to exhale.

The pressure of a column of air that is 10.3 m high has the same hydrostatic pressure as the atmospheric pressure. Yet, the maximum depth you could go with a snorkel is around 50 cm, i.e. one twentieth of that. Anything deeper would place too much of a load on your lungs that you won't be able to inhale or exhale.

So, your calculation was right in some sense. Suppose your lungs are 30 cm x 20 cm. That is an area of 0.06 m². Atmospheric pressure causes a pressure force of 6 kN, the equivalent of the weight of 600 kg (1,320 lb) on your chest and back! One twentieth of that is 30 kg (66 lb). So, this brings the calculated numbers to the ballpark of intuition. You see, it is this uncompensated extra pressure from the water that our bodies were not designed to tollerate. Even moderate depths cause failure.

 

[asteriatic]

I completely understand your concern about the intensity of atmospheric pressure. However, it is important to note that atmospheric pressure is not just a single force acting on a single point. It is the result of the weight of the entire column of air above a particular point. This means that the pressure is distributed over a large area, reducing the impact on any one point.

In addition, the human body is well adapted to withstand atmospheric pressure. Our bodies are made up of fluids, tissues, and bones that are able to withstand and equalize the pressure inside and outside of our bodies. This is why we do not feel the full force of atmospheric pressure on our bodies.

Furthermore, the Earth's atmosphere is constantly moving and changing, which also helps to distribute and equalize the pressure. This is why we do not feel the full force of atmospheric pressure even at high altitudes where the air is thinner.

Overall, while atmospheric pressure may seem intense when looked at in terms of force, it is important to consider its distribution and our body's ability to withstand and adapt to it. It is a natural and necessary force that helps to regulate our climate and sustain life on Earth.