Just how strong is the Air pressure

In summary: In fact, astronauts on the International Space Station experience almost the same air pressure as we do on Earth. The difference is the microgravity environment, which causes the body to adapt to a less strenuous environment and therefore lose some of its strength and density.
  • #1
AshUchiha
60
4
.

So, how does Air Pressure 'works' on Earth.
Would this right to say that, the air molecules present in the atmosphere are forced down due to gravity and thus applies force on every object downwards towards the Earth's core thus causing Air pressure?.

Another question I would like to know the answer of , is how do we even maintain stability at such intense amount of force acting on us everytime?
I mean our body exerts force from the inside resisting us from Crushing due to Air pressure, what about our own gravity which is trying to collapse ourself from the inside. How are we resisting that?

Also, I've heard that after coming back from the space you're bone density is lessened and other factors happen causing you to get weak. So if we have less inertia we can't resist much to Air resistance, so can I expect that if someone/something with very low inertia is expected to get crushed by the Air pressure? If this statement is true then I guess we will get daily reports of "Air Crush", but it's not true.So how??
 
Physics news on Phys.org
  • #2
Air particles are warm so they jiggle about, they bump into things, transferring momentum, this bumping is experienced as air pressure.
The Earth has air at all because gravity can hold it down.

Our own body produces enough internal pressure to oppose the pressure of the air and our own gravity ... our own gravity is easily balanced by electrosctatic repulsion between atoms and molecules just like you don't fall through the floor.

Inertia has nothing to do with resisting air pressure... reduced bone density can make your bones more brittle, so you could have a hard time standing against gravity. Also see oesteoporosis.
 
  • Like
Likes AshUchiha
  • #3
AshUchiha said:
.

So, how does Air Pressure 'works' on Earth.
Would this right to say that, the air molecules present in the atmosphere are forced down due to gravity and thus applies force on every object downwards towards the Earth's core thus causing Air pressure?.
No, air pressure is uniform in all directions, not just downwards.

Another question I would like to know the answer of , is how do we even maintain stability at such intense amount of force acting on us everytime?
I mean our body exerts force from the inside resisting us from Crushing due to Air pressure, what about our own gravity which is trying to collapse ourself from the inside. How are we resisting that?
We evolved in it and our bodies are completely accustomed to it.

Also, I've heard that after coming back from the space you're bone density is lessened and other factors happen causing you to get weak.
true

So if we have less inertia we can't resist much to Air resistance, so can I expect that if someone/something with very low inertia is expected to get crushed by the Air pressure? If this statement is true then I guess we will get daily reports of "Air Crush", but it's not true.So how??
inertia is something totally different and has nothing to do with air pressure or bone density
 
  • #4
Air pressure decreases with height... the pressure from above is less than the pressure from below. If the difference (times area) is more than the weight of the object, it is said to float. The effect is more pronounced in denser fluids like water... over small distances the air pressure can be treated as uniform in all directions.
Air pressure can also vary with the weather.
 
  • #5
AshUchiha said:
Another question I would like to know the answer of , is how do we even maintain stability at such intense amount of force acting on us everytime?
I mean our body exerts force from the inside resisting us from Crushing due to Air pressure,
Because things created upon the Earth do not do so by starting off with a vacuum inside. They start off in the presence of normal air pressure (or, sometimes, a lot more pressure).

By analogy, if you took a flat piece of paper and origami'ed it into a closed box, you would not expect it to suddenly implode.
AshUchiha said:
what about our own gravity which is trying to collapse ourself from the inside. How are we resisting that?
The gravitational force of a 50kg object is very, very small.
 
  • #6
AshUchiha said:
So, how does Air Pressure 'works' on Earth.
Would this right to say that, the air molecules present in the atmosphere are forced down due to gravity and thus applies force on every object downwards towards the Earth's core thus causing Air pressure?.
Do not forget to take into account the rotation of the planet, which causes winds. If you were in a room, with no wind, at sea level, you would experience 14.7 pounds of pressure per square inch. Not just downward, but from every direction.
AshUchiha said:
Another question I would like to know the answer of , is how do we even maintain stability at such intense amount of force acting on us everytime?
I mean our body exerts force from the inside resisting us from Crushing due to Air pressure, what about our own gravity which is trying to collapse ourself from the inside. How are we resisting that?
Our biology has evolved to the point where it can adapt to a particular environment. We have vertebrae and internal bones, instead of an exoskeleton, to deal with 9.8 m/s2. If you really want to know how we evolved to resist one atmospheric pressure or one gravity, then you will need to study 540 million years of biological evolution.
AshUchiha said:
Also, I've heard that after coming back from the space you're bone density is lessened and other factors happen causing you to get weak. So if we have less inertia we can't resist much to Air resistance, so can I expect that if someone/something with very low inertia is expected to get crushed by the Air pressure? If this statement is true then I guess we will get daily reports of "Air Crush", but it's not true.So how??
That is true. Long exposure to a weightless environment causes loss of bone density, and certain muscles begin to atrophy because they are not being used. Legs, for example, are rarely used in a weightless environment. Another serious factor, once we leave low-Earth orbit, will be solar and cosmic radiation. Biology and that kind of high energy radiation typically do not get along. They are already being subjected to the same 14.7 pounds per square inch on the ISS that you or I are subjected to at sea level.
 
  • #7
Simon Bridge said:
Inertia has nothing to do with resisting air pressure... reduced bone density can make your bones more brittle, so you could have a hard time standing against gravity. Also see oesteoporosis.

But inertia is the force exerted by the body to remain at the state of rest , resisting external forces. So Considering Air pressure as the external force isn't our inertia too acting against us being crushed by it?
 
  • #8
Simon Bridge said:
Our own body produces enough internal pressure to oppose the pressure of the air and our own gravity ... our own gravity is easily balanced by electrosctatic repulsion between atoms and molecules just like you don't fall through the floor.

Can you explain it more clearly?, about how we resist our own gravity.

phinds said:
We evolved in it and our bodies are completely accustomed to it.

So, Is there any specific ratio of how much the 'Inner gravity' would be according to the object's mass. We evolved to it, so can I say that our ancestors had a hard time facing with gravity?

Simon Bridge said:
Air particles are warm so they jiggle about, they bump into things, transferring momentum, this bumping is experienced as air pressure.
The Earth has air at all because gravity can hold it down.

If the cause of "jiggle effect" of Air particle due to exposure to heat, then would there be no Air pressure if there is no source of heat ?
 
  • #9
AshUchiha said:
So, Is there any specific ratio of how much the 'Inner gravity' would be according to the object's mass. We evolved to it, so can I say that our ancestors had a hard time facing with gravity?
You keep talking about gravity when I think you mean pressure, and no, our ancestors did not have any problem with either one. The evolved IN it, after all.
 
  • #10
As others have said, life on this planet including human life, has evolved to be adapted to the Earth environment.
The environment includes atmospheric pressure, gravity, and other things.
The prevailing atmospheric composition would be another one, as would be the solar radiation level, and probably more as well.
 
Last edited:
  • #11
AshUchiha said:
how do we even maintain stability at such intense amount of force acting on us everytime?

It really isn't so intense. The Venera landers on Venus got crushed (and melted, but that's a different story) after a few hours on surface because the Venusian atmosphere is so much denser than ours. Keep in mind the gravity there is pretty much the same as here, so just focus on air density. Same thing would happen to you if you went down the ocean. You wouldn't survive in either environment. Structurally, we're perfectly built for living here. The strength of the materials in our body and their shape is just right.

AshUchiha said:
If the cause of "jiggle effect" of Air particle due to exposure to heat, then would there be no Air pressure if there is no source of heat ?

That sounds like an absolute-zero scenario, which is not possible.
 
  • #12
An astronaut in space is still surrounded by air just like s/he is on earth. In fact, the air pressure maintained in the ISS, or a space suit, is comparable to atmospheric pressure on earth. Human beings do not react well to exposure to a vacuum. Unpleasant things occur, like ebullism and severe flatulence.
 
Last edited:
  • #13
phinds said:
You keep talking about gravity when I think you mean pressure, and no, our ancestors did not have any problem with either one. The evolved IN it, after all.

No sir, the one which you quoted was assuming if there is any specific ratio of an object's mass and it's own gravity. Or Would saying this be correct that Our mass M ∝ Our own gravity. And I see, we evolved IN it.
 
  • #14
Chronos said:
An astronaut in space is still surrounded by air just like s/he is on earth. In fact, the air pressure maintained in the ISS, or a space suit, is comparable to atmospheric pressure on earth. Human beings do not react well to exposure to a vacuum. Unpleasant things occur, like ebullism and severe flatulence.

I thought there is no gas present in space , it's totally empty except the Celestial objects and gases near these objects. And yes I've heard about how "human" would react to direct exposure to Vacuum, thanks for reminding me though :smile::wink:
 
  • #15
="AshUchiha, post: 5067692, member: 548974" And I see, we evolved IN it.
Yes we, humans and other stuff, evolved in the environment that we are in.
We could imagine living somewhere else, like Mars, but why really?.
I do not see a real possibiilty of interstellar 'colonisation', for Homo Sapiens, but I am prepared to be wrong about that.
 
Last edited:
  • #16
Well, there isn't any specific proofs for that though #rootone
 
  • #17
AshUchiha said:
Well, there isn't any specific proofs for that though #rootone
No, you can't prove a negative. If you want to colonize a planet other than Earth, even one in out own solar system, you can certainly hypothesize that it can be done but unless you can prove it, or come very close, you are wasting your time.
 
  • #18
AshUchiha said:
Can you explain it more clearly?, about how we resist our own gravity.

So, Is there any specific ratio of how much the 'Inner gravity' would be according to the object's mass. We evolved to it, so can I say that our ancestors had a hard time facing with gravity?
It is true. Your body is under the influence of the gravity caused by your mass. It is pulling you inward.
But consider: so is a feather in your hand. Or ping pong ball, or paperclip. They are all attracted toward you by your own gravity.

Do you see any of them flying toward your body and sticking to your stomach?
No. Because the gravity from a mass of human scale is vanishingly tiny. It's measurable, but you'd need instruments to detect it.

Gravitational attraction is not a significant force to contend with until you are dealing with objects the size of city blocks or more.
 
  • #19
AshUchiha said:
Well, there isn't any specific proofs for that though #rootone
No there are not.
Your application for intergalactic social support has been accepted, and we will try to find suitable housing for you.
 
  • Like
Likes phinds
  • #20
DaveC426913 said:
Do you see any of them flying toward your body and sticking to your stomach?
No. Because the gravity from a mass of human scale is vanishingly tiny. It's measurable, but you'd need instruments to detect it.

You mean to say our own gravity is slowly replinishing!? :nb):nb)
 
  • #21
AshUchiha said:
You mean to say our own gravity is slowly replinishing!? :nb):nb)
What are you talking about ?
 
  • #22
phinds said:
AshUchiha said:
You mean to say our own gravity is slowly replinishing!? :nb):nb)
What are you talking about ?
+1 phinds.

Replenishing means refilling or returning to a former value. I don't know how you got that from what I said. The gravity is not reducing or returning.
 
  • #23
DaveC426913 said:
+1 phinds.

Replenishing means refilling or returning to a former value. I don't know how you got that from what I said. The gravity is not reducing or returning.

Goodness! So in the absence of Air pressure am I supposed to explode ??
 
  • #24
Yes if you were suddenly teleported to outer space you would explode.
Well it would be more of gradually 'puffing up' as gases within your body seek equilibrium with the almost vacuum of space.
Some liquids would become gaseous, your blood would boil at normal blood temperature.
You would start leaking all over with small eruptions here and there as the gases break through your skin.
Severe flatulence may be expected too.
 
Last edited:
  • #25
I guess that's why they supply with a space suit which applies force on us every time while we wear it, to form an equilibrium, Is this right?

If it is, then what if they land up to a planet which has almost the same gravity as of Earth, they will implode?
 
  • #26
Yes that's right.
The primary purpose of a space suit is to keep your body in a survivable environment.
Air pressure is the most important consideration, but there are others such a temperature.

I'm not sure what you mean about the imploding, but if instead of bring teleported to outer space you were teleported to a planet with extreme gravity/atmospheric pressure compared to the surface of Earth, you would be crushed.
 
Last edited:
  • #27
rootone said:
Yes if you were suddenly teleported to outer space you would explode.
Well it would be more of gradually 'puffing up' as gases within your body seek equilibrium with the almost vacuum of space.
Some liquids would become gaseous, your blood would boil at normal blood temperature.
You would start leaking all over with small eruptions here and there as the gases break through your skin.
Severe flatulence may be expected too.
And by the way, some of those effects can happen if you scuba dive wrong, too.
 
  • #28
Yeah I was about to add that, but you got there first.
.. and there is only so far down a human being can go in the ocean before any kind of suit will not prevent them from being crushed.
Something stronger is needed, like a submarine, to provide a survivable environment.

... but there are creatures in the deep ocean which have adapted to it, and these would not survive if they were brought to the surface.
 
Last edited:
  • #29
AshUchiha said:
I guess that's why they supply with a space suit which applies force on us every time while we wear it, to form an equilibrium, Is this right?
Well, yes. Though the "force" is a flexible shell that contains air at less than 1 atmosphere of pressure. It does not "actively" compress us. See belowq

AshUchiha said:
If it is, then what if they land up to a planet which has almost the same gravity as of Earth, they will implode?
No. Same reason an astronaut in a spacesuit here on Earth doesn't implode. It's in equilibrium. The suit is not applying a force so much as it is containing an atmosphere. If atmo outside the suit balances atmo inside the suit, then they are in equilibrium, and the suit just stays slack.
 
  • #30
DaveC426913 said:
No. Same reason an astronaut in a spacesuit here on Earth doesn't implode. It's in equilibrium. The suit is not applying a force so much as it is containing an atmosphere. If atmo outside the suit balances atmo inside the suit, then they are in equilibrium, and the suit just stays slack.

Confusing, it can maintain us not exploding at the outer space. It means it's nearly as equal to our atmosphere pressure. If this statement is true, then if that man comes to Earth, the force exerted by the suit + atmospheric pressure would crush him down??

If my statement, is wrong. Then does the spacesuit applies the minimum force to maintain a stable shape {of us} ??
 
  • #31
The space suit, or a submarine, serve the function of keeping a human body in a safe shell, an environment which they can survive in.
Exposure to the environment outside the shell is lethal, so most people don't even think about trying it.
 
  • #32
rootone said:
The space suit, or a submarine, serve the function of keeping a human body in a safe shell, an environment which they can survive in.
Exposure to the environment outside the shell is lethal, so most people don't even think about trying it.

So my contradiction is correct?
 
  • #33
I'm not sure what the contradiction is.
The space suit or similar is providing air pressure which is similar to that at the surface of Earth.
Therefore the human being inside it is not exposed to pressure conditions which would cause physical breakdown and deformation of their body organs in a number of different ways.
Yes you could describe that as applying a force in that the pressurisation of the suit is achieved by using compressed air bottles, or a pump, but I don't see how that's very relevant, to the occupant, they are only interested in the suit providing a survivable environent
I guess that people who design space suits though - it must be for them a matter of great importance that the materials used are strong enough to maintain their integrity when subjected extreme differentials of pressure.
 
  • #34
I see, I've heard there are "chambers" which have very less gravity{which can make us float in that object"} I would like to know how it achieved?
 
  • #35
AshUchiha said:
I see, I've heard there are "chambers" which have very less gravity{which can make us float in that object"} I would like to know how it achieved?
What ARE you talking about? Do you mean swimming pools that are used to train astronauts? They are just swimming pools. The spacesuits are set to provide neutral buoyancy, but gravity is still there. Buoyancy and gravity are not the same thing.
 

Similar threads

Replies
27
Views
2K
Replies
50
Views
3K
Replies
9
Views
2K
Replies
8
Views
6K
Replies
20
Views
17K
Replies
4
Views
661
  • Introductory Physics Homework Help
Replies
15
Views
531
Replies
13
Views
4K
Back
Top