| Topic: |
Science > Physics |
| User: |
"" |
| Date: |
03 Dec 2005 05:22:17 PM |
| Object: |
Quick question about air pressure |
For easy math, lets just say I have a ten milliliter air tight
container. If I forced twenty milliliters of air into this container at
sea level, (about 14 psi, right?) would the pressure in the container
be about 28 psi?
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| User: "John Popelish" |
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| Title: Re: Quick question about air pressure |
03 Dec 2005 07:09:43 PM |
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wrote:
For easy math, lets just say I have a ten milliliter air tight
container. If I forced twenty milliliters of air into this container at
sea level, (about 14 psi, right?) would the pressure in the container
be about 28 psi?
If those pressures are absolute measurements (psia), then yes. If you
measure with respect to the atmosphere around the container (gauge
pressure), then the after pressure would be 14 psig.
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| User: "Gregory L. Hansen" |
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| Title: Re: Quick question about air pressure |
03 Dec 2005 05:28:57 PM |
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In article <1133652137.826518.66570@g47g2000cwa.googlegroups.com>,
<ngdbud@hotmail.com> wrote:
For easy math, lets just say I have a ten milliliter air tight
container. If I forced twenty milliliters of air into this container at
sea level, (about 14 psi, right?) would the pressure in the container
be about 28 psi?
Quick answer: yes
--
"Not that there's anything wrong with just lying around on your back. In
its way, rotting is interesing too... It's just that there are other ways
to spend your time as a cadaver." -- Mary Roach, "Stiff", 2003.
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| User: "The Ghost In The Machine" |
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| Title: Re: Quick question about air pressure |
03 Dec 2005 08:00:05 PM |
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In sci.physics,
<>
wrote
on 3 Dec 2005 15:22:17 -0800
<1133652137.826518.66570@g47g2000cwa.googlegroups.com>:
For easy math, lets just say I have a ten milliliter air tight
container. If I forced twenty milliliters of air into this container at
sea level, (about 14 psi, right?) would the pressure in the container
be about 28 psi?
Depends on a number of factors:
PV = nRT
P = pressure
V = volume
n = air amount, in moles
R = Rydberg's Constant, which is about 8.314472 J/(mol K)
T = temperature (in degrees Kelvin)
Assuming one can hold T constant, and that both 10 ml and 20 ml
of air is measured at constant P (101325 Pascal, or 14.7 psi)
and then forced into the chamber, the pressure would be doubled
(202650 Pascal or 29.4 psi).
However, injecting air under pressure will usually raise the
temperature. I don't know how much offhand, although the amount
of work to isothermally compress air from 20 ml to 10 ml isn't
too hard to calculate; it's an(integral of force times distance, where
force is inversely proportional to piston displacement.
--
#191,
It's still legal to go .sigless.
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