How strong is air pressure?

  • Thread starter BigMacnFries
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  • #1
BigMacnFries

Main Question or Discussion Point

I have read that air pressure is about 100,000 pascalls
which = 100,000 newtons/m2
which is enough to accelarate a 1kg body with a surface area of 1m2 to 100,000 m/s in one second
which is enough to accelarate a 100kg body with a surface area of 1m2 to 1000m/s in one second.
Is this right. Since i am about 100kg and have a front body surface of about 1m2 is it true that if the air pressure on my back suddenly dissaperaed I would be 1km that way in a little over a second?
 

Answers and Replies

  • #2
chroot
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An object with a one-meter-squared side experiences a little over a hundred thousand newtons of force, over that area, due to atmospheric air pressure.

If there were absolutely no opposing forces, such an object with a mass of only 1 kg would experience an acceleration of a little over 100,000 m/s^2.

Of course, it would be quite a feat to arrange a system in which the pressure did not change at all as the object were accelerated. Consider a potato gun or pneumatic rifle. As the projectile begins moving, the cavity behind it gets larger, and the pressure in that cavity is reduced. When fired with atmospheric pressure into a vacuum, the projectile would experience that 100,000 m/s^2 acceleration only instantaneously at the beginning of its movement; at all later times the acceleration would be much less.

Anecdotally, air pressure can store very large amounts of energy. A scuba tank exploding inside a dive shop, for example, can pretty much destroy the whole shop.

- Warren
 
  • #3
russ_watters
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chroot said:
Anecdotally, air pressure can store very large amounts of energy. A scuba tank exploding inside a dive shop, for example, can pretty much destroy the whole shop. [emphasis added]
"Anecdotally"? :surprised Did you really think we could let that go without expansion (pun weak, but intended)?
 
  • #4
Chronos
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You would not want to be in your body if the earth suddenly lost its measly 15 psi atmosphere. Your blood would boil, lungs collapse... and it gets ugly after that.
 
  • #5
BigMacnFries
Why would my blood boil etc?
 
  • #6
Astronuc
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Boiling point is dependent on pressure.

Blood is mostly water.

The saturation temperature of water at 0.04 bars (1 atm = 1.01325 bar = 14.696 psia) is 29.0°C (84.1°F). So if the temperature of blood is about 98.6°F (37°C), the blood would boil at 0.04 bar, which is still greater than vacuum (<<0.01 bar).
 

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