Specific weight

The specific weight, also known as the unit weight, is a volume-specific quantity defined as the weight divided by the volume of a material:
Equivalently, it may also be formulated as the product of density,, and gravity acceleration, :
Its unit of measurement in the International System of Units is the newton per cubic metre, expressed in terms of base units as kg⋅m⁻²⋅s⁻².
A commonly used value is the specific weight of water on Earth at, which is.

Discussion

The density of a material is defined as mass divided by volume, typically expressed with the unit kg/m³.
Unlike density, specific weight is not a fixed property of a material, as it depends on the value of the gravitational acceleration, which varies with location.
In practice, the standard gravity is often assumed, usually taken as.
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.

Applications

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. Specific weight can be used as a characteristic property of a fluid.

Soil mechanics

Specific weight is often used as a property of soil to solve earthwork problems.
In soil mechanics, specific weight may refer to:

Civil and mechanical engineering

Specific weight can be used in civil engineering and 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	Specific weight
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

Temperature	Specific weight
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 air

Temperature	Specific weight
−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

Temperature	Specific weight
−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