How 101325 N/m2 or Pascal is derived? Please explain simply.

1 Answer
A08
Aug 12, 2017

This is link to the resolution adopted by the official body for Standards to define Standard Pressure.

The adopted value could be intended to represent the mean atmospheric pressure at mean sea level at the latitude of a specific place. (I am not sure if this place is Paris.)

The reason for adopting this number will be known only to the body.
However, we can make an intelligent guess.

We can arrive at approximate value of Standard Atmosphere around this number.

#1# atm#=1# Standard Atmosphere #=1.01325×10^5# Pa #≡ 760# Torr

#1# Torr#~~1# mm Hg
(for most practical purposes Torr and mm Hg, #0^@#C are often taken to be identical.)

#:.1# atm#~~760# mm Hg

Weight of a column of #760# mm of Hg in SI units would be

#="mass " mxx"gravity "g#
#="Volume"xx"Density of mercury*"xx"Gravity"#
#=(0.760xx"unit area")xx(13595.08)xx(9.80665)#
#=101324.87" N"#

#"Pressure"="Weight"/"Area"=101324.87/"Unit Area"=101324.87" Nm"^-2#

#:.#The Calculated value is #~~# to the Standard value.

#"*"# Value of Density taken at #0^@"C"#

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