Newton's rings: Difference between revisions
en>Maury Markowitz mNo edit summary |
|||
Line 1: | Line 1: | ||
< | {{Distinguish|specific gravity}} | ||
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]]). | |||
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>. | |||
<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 | |||
</ref> | |||
The terms ''[[specific gravity]]'', and less often ''specific weight'', are also used for [[relative density]]. | |||
==General formula== | |||
:<math>\gamma = \rho \, g</math> | |||
where | |||
:<math>\gamma</math> is the specific weight of the material ([[weight]] per unit [[volume]], typically N/m<sup>3</sup> units) | |||
:<math>\rho</math> is the [[density]] of the material ([[mass]] per unit [[volume]], typically kg/m<sup>3</sup>) | |||
:<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>) | |||
==Changes of specific weight== | |||
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" /> | |||
==Uses== | |||
===Fluid mechanics=== | |||
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" /> | |||
===Soil mechanics=== | |||
Specific weight is used as a property of soil often used to solve [[Earthworks (engineering)|earthwork]] problems. | |||
In soil mechanics, specific weight may refer to: | |||
*'''Moist unit weight''', which is the unit weight of a soil when void spaces of the soil contain both water and air. | |||
:<math>\gamma = \frac{(1+w)G_s\gamma_w}{1+e}</math> | |||
where | |||
:<math>\gamma</math> is the moist unit weight of the material | |||
:<math>\gamma_w</math> is the unit weight of water | |||
:w is the [[moisture content]] of the material | |||
:Gs is the [[specific gravity]] of the solid | |||
:e is the [[void ratio]] | |||
*'''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. | |||
The formula for dry unit weight is: | |||
:<math>\gamma_d = \frac{G_s\gamma_w}{1+e} = \frac{\gamma}{1+w}</math> | |||
where | |||
:<math>\gamma</math> is the moist unit weight of the material | |||
:<math>\gamma_d</math> is the dry unit weight of the material | |||
:<math>\gamma_w</math> is the unit weight of water | |||
:w is the [[moisture content]] of the material | |||
:Gs is the [[specific gravity]] of the solid | |||
:e is the [[void ratio]] | |||
Typical values of soil dry unit weight can be found on [http://www.geotechdata.info/parameter/soil-dry-unit-weight.html geotechdata.info database]. | |||
*'''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. | |||
The formula for saturated unit weight is: | |||
:<math>\gamma_s = \frac{(G_s+e)\gamma_w}{1+e}</math> | |||
where | |||
:<math>\gamma_s</math> is the saturated unit weight of the material | |||
:<math>\gamma_w</math> is the unit weight of water | |||
:w is the [[moisture content]] of the material | |||
:Gs is the [[specific gravity]] of the solid | |||
: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> | |||
*'''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. | |||
The formula for submerged unit weight is: | |||
:<math>\gamma^' = \gamma_s - \gamma_w</math> | |||
where | |||
:<math>\gamma^'</math> is the submerged unit weight of the material | |||
:<math>\gamma_s</math> is the saturated unit weight of the material | |||
:<math>\gamma_w</math> is the unit weight of water | |||
===Mechanical engineering=== | |||
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]]. | |||
==Specific weight of water== | |||
{| class="wikitable" style="text-align:center" | |||
|- | |||
!Temperature(°F)!! Specific weight (lb/ft<sup>3</sup>) | |||
|- | |||
| 32 || 62.42 | |||
|- | |||
| 40 || 62.43 | |||
|- | |||
| 50 || 62.41 | |||
|- | |||
| 60 || 62.37 | |||
|- | |||
| 70 || 62.30 | |||
|- | |||
| 80 || 62.22 | |||
|- | |||
| 90 || 62.11 | |||
|- | |||
| 100 || 62.00 | |||
|- | |||
| 110 || 61.86 | |||
|- | |||
| 120 || 61.71 | |||
|- | |||
| 130 || 61.55 | |||
|- | |||
| 140 || 61.38 | |||
|- | |||
| 150 || 61.20 | |||
|- | |||
| 160 || 61.00 | |||
|- | |||
| 170 || 60.80 | |||
|- | |||
| 180 || 60.58 | |||
|- | |||
| 190 || 60.36 | |||
|- | |||
| 200 || 60.12 | |||
|- | |||
| 212 || 59.83 | |||
|- | |||
| 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> | |||
|} | |||
{| class="wikitable" style="text-align:center" | |||
|- | |||
!Temperature(°C)!! Specific weight (kN/m<sup>3</sup>) | |||
|- | |||
| 0 || 9.805 | |||
|- | |||
| 5 || 9.807 | |||
|- | |||
| 10 || 9.804 | |||
|- | |||
| 15 || 9.798 | |||
|- | |||
| 20 || 9.789 | |||
|- | |||
| 25 || 9.777 | |||
|- | |||
| 30 || 9.765 | |||
|- | |||
| 40 || 9.731 | |||
|- | |||
| 50 || 9.690 | |||
|- | |||
| 60 || 9.642 | |||
|- | |||
| 70 || 9.589 | |||
|- | |||
| 80 || 9.530 | |||
|- | |||
| 90 || 9.467 | |||
|- | |||
| 100 || 9.399 | |||
|- | |||
| colspan="2" align="center" style="font-size:80%" | Specific weight of water at standard sea-level atmospheric pressure (Metric units) <ref name="fluids" /> | |||
|} | |||
==Specific weight of air== | |||
{| class="wikitable" style="text-align:center" | |||
|- | |||
!Temperature(°F)!! Specific Weight (lb/ft<sup>3</sup>) | |||
|- | |||
| −40 || | |||
|- | |||
| −20 || 0.0903 | |||
|- | |||
| 0 || 0.08637 | |||
|- | |||
| 10 || 0.08453 | |||
|- | |||
| 20 || 0.08277 | |||
|- | |||
| 30 || 0.08108 | |||
|- | |||
| 40 || 0.07945 | |||
|- | |||
| 50 || 0.0779 | |||
|- | |||
| 60 || 0.0764 | |||
|- | |||
| 70 || 0.07495 | |||
|- | |||
| 80 || 0.07357 | |||
|- | |||
| 90 || 0.07223 | |||
|- | |||
| 100 || 0.07094 | |||
|- | |||
| 120 || 0.06849 | |||
|- | |||
| 140 || 0.0662 | |||
|- | |||
| 160 || 0.06407 | |||
|- | |||
| 180 || 0.06206 | |||
|- | |||
| 200 || 0.06018 | |||
|- | |||
| 250 || 0.05594 | |||
|- | |||
| colspan="3" align="center" style="font-size:80%" | Specific weight of air at standard sea-level atmospheric pressure (English units) <ref name="fluids" /> | |||
|} | |||
{| class="wikitable" style="text-align:center" | |||
|- | |||
!Temperature(°C)!! Specific weight (N/m<sup>3</sup>) | |||
|- | |||
| −40 || 14.86 | |||
|- | |||
| −20 || 13.86 | |||
|- | |||
| 0 || 12.68 | |||
|- | |||
| 10 || 12.24 | |||
|- | |||
| 20 || 11.82 | |||
|- | |||
| 30 || 11.43 | |||
|- | |||
| 40 || 11.06 | |||
|- | |||
| 60 || 10.4 | |||
|- | |||
| 80 || 9.81 | |||
|- | |||
| 100 || 9.28 | |||
|- | |||
| 200 || 7.33 | |||
|-100 ii 89 | |||
| colspan="3" align="center" style="font-size:80%" | Specific weight of air at standard sea-level atmospheric pressure (Metric units) <ref name="fluids" /> | |||
|} | |||
== See also == | |||
* [[Density]] | |||
* [[Relative density]] | |||
* [[Specific gravity]] | |||
* | |||
==References== | |||
{{Reflist}} | |||
==External links== | |||
* [http://www.arrowweights.com/ Water Weights & Weight Belts (Arrow Weights Manufacturing)] | |||
* http://www.engineeringtoolbox.com/density-specific-weight-gravity-d_290.html | |||
* http://www.themeter.net/pesi-spec_e.htm | |||
[[Category:Soil mechanics]] | |||
[[Category:Fluid mechanics]] | |||
[[Category:Physical chemistry]] | |||
[[Category:Physical quantities]] | |||
[[Category:Density]] |
Revision as of 01:47, 25 January 2014
Template:Distinguish 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).
A commonly used value is the specific weight of water on Earth at 5°C which is 62.43 lbf/ft3 or 9.807 kN/m3. [1]
The terms specific gravity, and less often specific weight, are also used for relative density.
General formula
where
- is the specific weight of the material (weight per unit volume, typically N/m3 units)
- is the density of the material (mass per unit volume, typically kg/m3)
- is acceleration due to gravity (rate of change of velocity, given in m/s2, and on Earth usually given as 9.81 m/s2)
Changes of specific weight
Unlike density, specific weight is not 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. [2]
Uses
Fluid mechanics
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/ft3 or N/m3). Specific weight can be used as a characteristic property of a fluid. [2]
Soil mechanics
Specific weight is used as a property of soil often used to solve earthwork problems.
In soil mechanics, specific weight may refer to:
- Moist unit weight, which is the unit weight of a soil when void spaces of the soil contain both water and air.
where
- is the moist unit weight of the material
- is the unit weight of water
- w is the moisture content of the material
- Gs is the specific gravity of the solid
- e is the void ratio
- 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.
The formula for dry unit weight is:
where
- is the moist unit weight of the material
- is the dry unit weight of the material
- is the unit weight of water
- w is the moisture content of the material
- Gs is the specific gravity of the solid
- e is the void ratio
Typical values of soil dry unit weight can be found on geotechdata.info database.
- 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.
The formula for saturated unit weight is:
where
- is the saturated unit weight of the material
- is the unit weight of water
- w is the moisture content of the material
- Gs is the specific gravity of the solid
- e is the void ratio[3]
- Submerged unit weight, which is defined as the difference between the saturated unit weight and the unit weight of water. [4] It is often used in the calculation of the effective stress in a soil.
The formula for submerged unit weight is:
where
- is the submerged unit weight of the material
- is the saturated unit weight of the material
- is the unit weight of water
Mechanical engineering
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.
Specific weight of water
Temperature(°F) | Specific weight (lb/ft3) |
---|---|
32 | 62.42 |
40 | 62.43 |
50 | 62.41 |
60 | 62.37 |
70 | 62.30 |
80 | 62.22 |
90 | 62.11 |
100 | 62.00 |
110 | 61.86 |
120 | 61.71 |
130 | 61.55 |
140 | 61.38 |
150 | 61.20 |
160 | 61.00 |
170 | 60.80 |
180 | 60.58 |
190 | 60.36 |
200 | 60.12 |
212 | 59.83 |
Specific weight of water at standard sea-level atmospheric pressure (English units) [2] |
Temperature(°C) | Specific weight (kN/m3) |
---|---|
0 | 9.805 |
5 | 9.807 |
10 | 9.804 |
15 | 9.798 |
20 | 9.789 |
25 | 9.777 |
30 | 9.765 |
40 | 9.731 |
50 | 9.690 |
60 | 9.642 |
70 | 9.589 |
80 | 9.530 |
90 | 9.467 |
100 | 9.399 |
Specific weight of water at standard sea-level atmospheric pressure (Metric units) [2] |
Specific weight of air
Temperature(°F) | Specific Weight (lb/ft3) | |
---|---|---|
−40 | ||
−20 | 0.0903 | |
0 | 0.08637 | |
10 | 0.08453 | |
20 | 0.08277 | |
30 | 0.08108 | |
40 | 0.07945 | |
50 | 0.0779 | |
60 | 0.0764 | |
70 | 0.07495 | |
80 | 0.07357 | |
90 | 0.07223 | |
100 | 0.07094 | |
120 | 0.06849 | |
140 | 0.0662 | |
160 | 0.06407 | |
180 | 0.06206 | |
200 | 0.06018 | |
250 | 0.05594 | |
Specific weight of air at standard sea-level atmospheric pressure (English units) [2] |
Temperature(°C) | Specific weight (N/m3) | |
---|---|---|
−40 | 14.86 | |
−20 | 13.86 | |
0 | 12.68 | |
10 | 12.24 | |
20 | 11.82 | |
30 | 11.43 | |
40 | 11.06 | |
60 | 10.4 | |
80 | 9.81 | |
100 | 9.28 | |
200 | 7.33 | |
Specific weight of air at standard sea-level atmospheric pressure (Metric units) [2] |
See also
References
43 year old Petroleum Engineer Harry from Deep River, usually spends time with hobbies and interests like renting movies, property developers in singapore new condominium and vehicle racing. Constantly enjoys going to destinations like Camino Real de Tierra Adentro.
External links
- Water Weights & Weight Belts (Arrow Weights Manufacturing)
- http://www.engineeringtoolbox.com/density-specific-weight-gravity-d_290.html
- http://www.themeter.net/pesi-spec_e.htm
- ↑ 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
- ↑ 2.0 2.1 2.2 2.3 2.4 2.5 Finnemore, J. E. (2002). Fluid Mechanics with Engineering Applications. New York: McGraw-Hill. ISBN 0-07-243202-0.
- ↑ Das, Braja M. (2007). Principles of Geotechnical Engineering. Canada: Chris Carson. ISBN 0-495-07316-4.
- ↑ 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