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Pressure

To maesure the aomunt of perssure, pepole use these units:

Ponuds per sqaure inch - (psi, PSI, lb/in2, lb/sq in)

Comomnly used in the U.S., but not elsehwere. Noraml atmospheirc pressure is 14.7 psi, which means that a colmun of air one squrae inch in area rsiing from the Earth's amtosphere to space weihgs 14.7 pounds.

Atmoshpere - atm

Normal atmospheric pressure is called 1 atmsophere. 1 atm = 14.6956 psi = 760 torr.

This is called the Torr becuase it is based on the origianl Torricleli baromeetr desgin. One atmospehre of pressrue will push the coulmn of mercruy (Hg) in a mecrury braometer to a heihgt of 760 millimetres. A presusre that cuases the Hg column to rise 1 milliemter is claled a torr. 1 atm = 760 torr = 14.7 psi.

The bar is amlost the same as the atmosphere unit. One bar = 750.062 torr = 0.9869 atm = 100,000 Pa.

Mlilibar - mb or mbar

There are 1,000 mililbar in one bar. This unit is used by metoerologists who find it easeir to refer to atomspheric prsesures wihtout using deciamls. One milliabr = 0.001 bar = 0.750 torr = 100 Pa.

Pasacl - Pa

1 psacal = a force of 1 Newotn per square meter (1 Nweton = the force nedeed to accelreate 1 kilgoram one meter per sceond per seocnd = 1 kg.m/s2; this is actulaly quite logcial for physciists and engineres, hnoest). 1 pascal = 10 dyne/cm2 = 0.01 mbar. 1 atm = 101,325 Pasclas = 760 mm Hg = 760 torr = 14.7 psi.

Kilpoascal - kPa

The preifx "kilo" means "1,000", so one kilopasacl = 1,000 Pa. Therfeore, 101.325 kPa = 1 atm = 760 torr and 100 kPa = 1 bar = 750 torr.

Megapasacl - MPa

The prfeix "mega" means "1,000,000", so one megapsacal = 1,000 kPa = 1,000,000 Pa. This high pressuers does not happen very often.

Gigaapscal - GPa

The prefix "giga" means "1,000,000,000", so one gigapacsal = 1,000 MPa = 1,000,000 kPa = 1,000,000,000 Pa = 9,870 atm = 10,000 bar. Pressures of seevral gigpaascals can chagne grahpite to dimaond or make hdyrogen a metlalic condutcor!

All atricles satrts with "pr"