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| {{Distinguish|specific gravity}}
| | Nice to satisfy you, my title is Refugia. Years in the past we moved to North Dakota. My day occupation is a meter reader. To gather coins is a thing that I'm totally addicted to.<br><br>Also visit my web site ... [http://mail.muzblogs.ru/profile/admcdonoug std testing at home] |
| The '''specific weight''' (also known as the '''unit weight''') is the [[weight]] per unit [[volume]] of a material. The symbol of specific weight is '''γ''' (the Greek letter [[Gamma]]).
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| A commonly used value is the specific weight of [[water]] on [[Earth]] at 5°C which is 62.43 [[Pound-force|lbf]]/ft<sup>3</sup> or 9.807 kN/m<sup>3</sup>.
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| <ref name="FE"> National Council of Examiners for Engineering and Surveying (2005). Fundamentals of Engineering Supplied-Reference Handbook (7th ed.). Clemson: National Council of Examiners for Engineering and Surveying. ISBN 1-932613-00-5
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| </ref>
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| The terms ''[[specific gravity]]'', and less often ''specific weight'', are also used for [[relative density]].
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| ==General formula==
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| :<math>\gamma = \rho \, g</math>
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| where
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| :<math>\gamma</math> is the specific weight of the material ([[weight]] per unit [[volume]], typically N/m<sup>3</sup> units)
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| :<math>\rho</math> is the [[density]] of the material ([[mass]] per unit [[volume]], typically kg/m<sup>3</sup>)
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| :<math>g</math> is [[standard gravity|acceleration due to gravity]] (rate of change of [[velocity]], given in m/s<sup>2</sup>, and on Earth usually given as 9.81 m/s<sup>2</sup>)
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| ==Changes of specific weight==
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| Unlike density, specific weight is not [[wikt:absolute|absolute]]. It depends upon the value of the [[gravitational acceleration]], which varies with location. A significant influence upon the value of specific gravity is the [[temperature ]] of the material. [[Pressure]] may also affect values, depending upon the [[bulk modulus]] of the material, but generally, at moderate pressures, has a less significant effect than the other factors. <ref name="fluids" />
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| ==Uses==
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| ===Fluid mechanics===
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| In [[fluid mechanics]], specific weight represents the [[force]] exerted by [[gravity]] on a unit volume of a fluid. For this reason, units are expressed as force per unit volume (e.g., lb/ft<sup>3</sup> or N/m<sup>3</sup>). Specific weight can be used as a characteristic [[List of materials properties|property]] of a fluid. <ref name="fluids" />
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| ===Soil mechanics===
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| Specific weight is used as a property of soil often used to solve [[Earthworks (engineering)|earthwork]] problems.
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| In soil mechanics, specific weight may refer to:
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| *'''Moist unit weight''', which is the unit weight of a soil when void spaces of the soil contain both water and air.
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| :<math>\gamma = \frac{(1+w)G_s\gamma_w}{1+e}</math>
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| where
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| :<math>\gamma</math> is the moist unit weight of the material
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| :<math>\gamma_w</math> is the unit weight of water
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| :w is the [[moisture content]] of the material
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| :Gs is the [[specific gravity]] of the solid
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| :e is the [[void ratio]]
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| *'''Dry unit weight''', which is the unit weight of a soil when all void spaces of the soil are completely filled with air, with no water.
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| The formula for dry unit weight is:
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| :<math>\gamma_d = \frac{G_s\gamma_w}{1+e} = \frac{\gamma}{1+w}</math>
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| where
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| :<math>\gamma</math> is the moist unit weight of the material
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| :<math>\gamma_d</math> is the dry unit weight of the material
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| :<math>\gamma_w</math> is the unit weight of water
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| :w is the [[moisture content]] of the material
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| :Gs is the [[specific gravity]] of the solid
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| :e is the [[void ratio]]
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| Typical values of soil dry unit weight can be found on [http://www.geotechdata.info/parameter/soil-dry-unit-weight.html geotechdata.info database].
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| *'''Saturated unit weight''', which is the unit weight of a soil when all void spaces of the soil are completely filled with water, with no air.
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| The formula for saturated unit weight is:
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| :<math>\gamma_s = \frac{(G_s+e)\gamma_w}{1+e}</math>
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| where
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| :<math>\gamma_s</math> is the saturated unit weight of the material
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| :<math>\gamma_w</math> is the unit weight of water
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| :w is the [[moisture content]] of the material
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| :Gs is the [[specific gravity]] of the solid
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| :e is the [[void ratio]]<ref name="soils">Das, Braja M. (2007). ''Principles of Geotechnical Engineering''. Canada: Chris Carson. ISBN 0-495-07316-4. </ref>
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| *'''Submerged unit weight''', which is defined as the difference between the saturated unit weight and the unit weight of water. <ref name="Intelligent Compaction"> The Transtec Group, Inc. (2012). ''Basic Definitions and Terminology of Soils''. http://www.intelligentcompaction.com/downloads/IC_RelatedDocs/SoilCmpct_Basic%20definitions%20of%20Soils.pdf (Page viewed December 7, 2012 </ref> It is often used in the calculation of the [[effective stress]] in a soil.
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| The formula for submerged unit weight is:
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| :<math>\gamma^' = \gamma_s - \gamma_w</math>
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| where
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| :<math>\gamma^'</math> is the submerged unit weight of the material
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| :<math>\gamma_s</math> is the saturated unit weight of the material
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| :<math>\gamma_w</math> is the unit weight of water
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| ===Mechanical engineering===
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| Specific weight can be used in [[mechanical engineering]] to determine the weight of a structure designed to carry certain loads while remaining intact and remaining within limits regarding [[deformation (engineering)|deformation]].
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| ==Specific weight of water==
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| {| class="wikitable" style="text-align:center"
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| |-
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| !Temperature(°F)!! Specific weight (lb/ft<sup>3</sup>)
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| | 32 || 62.42
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| |-
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| | 40 || 62.43
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| |-
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| | 50 || 62.41
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| |-
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| | 60 || 62.37
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| |-
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| | 70 || 62.30
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| |-
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| | 80 || 62.22
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| |-
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| | 90 || 62.11
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| |-
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| | 100 || 62.00
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| |-
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| | 110 || 61.86
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| |-
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| | 120 || 61.71
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| |-
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| | 130 || 61.55
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| |-
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| | 140 || 61.38
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| |-
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| | 150 || 61.20
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| |-
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| | 160 || 61.00
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| |-
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| | 170 || 60.80
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| |-
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| | 180 || 60.58
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| |-
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| | 190 || 60.36
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| |-
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| | 200 || 60.12
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| |-
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| | 212 || 59.83
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| |-
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| | colspan="2" align="center" style="font-size:80%" | Specific weight of water at standard sea-level atmospheric pressure (English units) <ref name="fluids"> Finnemore, J. E. (2002). ''Fluid Mechanics with Engineering Applications''. New York: McGraw-Hill. ISBN 0-07-243202-0. </ref>
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| |}
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| {| class="wikitable" style="text-align:center"
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| !Temperature(°C)!! Specific weight (kN/m<sup>3</sup>)
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| | 0 || 9.805
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| |-
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| | 5 || 9.807
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| | 10 || 9.804
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| | 15 || 9.798
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| | 20 || 9.789
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| | 25 || 9.777
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| | 30 || 9.765
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| |-
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| | 40 || 9.731
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| | 50 || 9.690
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| | 60 || 9.642
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| | 70 || 9.589
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| |-
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| | 80 || 9.530
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| |-
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| | 90 || 9.467
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| | 100 || 9.399
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| |-
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| | colspan="2" align="center" style="font-size:80%" | Specific weight of water at standard sea-level atmospheric pressure (Metric units) <ref name="fluids" />
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| |}
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| ==Specific weight of air==
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| {| class="wikitable" style="text-align:center"
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| !Temperature(°F)!! Specific Weight (lb/ft<sup>3</sup>)
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| | −40 ||
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| | −20 || 0.0903
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| | 0 || 0.08637
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| | 10 || 0.08453
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| | 20 || 0.08277
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| |-
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| | 30 || 0.08108
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| | 40 || 0.07945
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| | 50 || 0.0779
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| | 60 || 0.0764
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| |-
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| | 70 || 0.07495
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| | 80 || 0.07357
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| | 90 || 0.07223
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| | 100 || 0.07094
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| | 120 || 0.06849
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| | 140 || 0.0662
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| | 160 || 0.06407
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| | 180 || 0.06206
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| |-
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| | 200 || 0.06018
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| | 250 || 0.05594
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| |-
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| | colspan="3" align="center" style="font-size:80%" | Specific weight of air at standard sea-level atmospheric pressure (English units) <ref name="fluids" />
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| |}
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| {| class="wikitable" style="text-align:center"
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| !Temperature(°C)!! Specific weight (N/m<sup>3</sup>)
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| | −40 || 14.86
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| |-
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| | −20 || 13.86
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| | 0 || 12.68
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| |-
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| | 10 || 12.24
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| |-
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| | 20 || 11.82
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| | 30 || 11.43
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| | 40 || 11.06
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| | 60 || 10.4
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| | 80 || 9.81
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| |-
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| | 100 || 9.28
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| | 200 || 7.33
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| |-100 ii 89
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| | colspan="3" align="center" style="font-size:80%" | Specific weight of air at standard sea-level atmospheric pressure (Metric units) <ref name="fluids" />
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| |}
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| == See also ==
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| * [[Density]]
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| * [[Relative density]]
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| * [[Specific gravity]]
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| *
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| ==References==
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| {{Reflist}}
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| ==External links==
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| * [http://www.arrowweights.com/ Water Weights & Weight Belts (Arrow Weights Manufacturing)]
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| * http://www.engineeringtoolbox.com/density-specific-weight-gravity-d_290.html
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| * http://www.themeter.net/pesi-spec_e.htm
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| [[Category:Soil mechanics]]
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| [[Category:Fluid mechanics]]
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| [[Category:Physical chemistry]]
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| [[Category:Physical quantities]]
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| [[Category:Density]]
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Nice to satisfy you, my title is Refugia. Years in the past we moved to North Dakota. My day occupation is a meter reader. To gather coins is a thing that I'm totally addicted to.
Also visit my web site ... std testing at home