Description
The speed of sound in air is around 768 mi/hr (1,125 ft/sec, 343 m/sec), or about 5 seconds per mile, or 3 seconds per kilometer. That is the reason for the rule of thumb where when you see a flash of lightning, count the number of seconds until you hear the thunderclap, then divide by five. That gives you the approximate distance (in miles) away from the lightning. Divide by three for kilometers. Speed of sound very important for an application to ultrasonic flow meter or ultrasonic level sensor.
The speed of sound in any medium is dependent upon the coefficient of stiffness (modulus of bulk elasticity for gas mediums). Density and/or compressibility alone does not determine the speed of sound.
- Vl = Velocity of a plane longitudinal wave in bulk material.
- Vs = Velocity of a plane transverse (shear) wave.
- Vext = Velocity of longitudinal wave (extensional wave) in thin rods.
Solids |
||||
|
Substance
|
Density
(g/cm3) |
Vl(m/s)
|
Vs(m/s)
|
Vext(m/s)
|
|
Metals
|
||||
|
Aluminum rolled
|
2.7
|
6420
|
3040
|
5000
|
|
Beryllium
|
1.87
|
12890
|
8880
|
12870
|
|
Brass (70 Cu, 30 Zn)
|
8.6
|
4700
|
2110
|
3480
|
|
Copper, annealed
|
8.93
|
4760
|
2325
|
3810
|
|
Copper rolled
|
8.93
|
5010
|
2270
|
3750
|
|
Gold, hard-drawn
|
19.7
|
3240
|
1200
|
2030
|
|
Iron, Armco
|
7.85
|
5960
|
3240
|
5200
|
|
Lead, annealed
|
11.4
|
2160
|
700
|
1190
|
|
Lead, rolled
|
11.4
|
1960
|
690
|
1210
|
|
Molybdenum
|
10.1
|
6250
|
3350
|
5400
|
|
Monel metal
|
8.90
|
5350
|
2720
|
4400
|
|
Nickel (unmagnetized)
|
8.85
|
5480
|
2990
|
4800
|
|
Nickel
|
8.9
|
6040
|
3000
|
4900
|
|
Platinum
|
21.4
|
3260
|
1730
|
2800
|
|
Silver
|
10.4
|
3650
|
1610
|
2680
|
|
Steel, mild
|
7.85
|
5960
|
3235
|
5200
|
|
Steel, 347 Stainless
|
7.9
|
5790
|
3100
|
5000
|
|
Tin rolled
|
7.3
|
3320
|
1670
|
2730
|
|
Titanium
|
4.5
|
6070
|
3125
|
5080
|
|
Tungsten, annealed
|
19.3
|
5220
|
2890
|
4620
|
|
Tungsten Carbide
|
13.8
|
6655
|
3980
|
6220
|
|
Zinc rolled
|
7.1
|
4210
|
2440
|
3850
|
|
Various
|
||||
|
Fused silica
|
2.2
|
5968
|
3764
|
5760
|
|
Glass, pyrex
|
2.32
|
5640
|
3280
|
5170
|
|
Glass, heavy silicate flint
|
3.88
|
3980
|
2380
|
3720
|
|
Lucite
|
1.18
|
2680
|
1100
|
1840
|
|
Nylon 6-6
|
1.11
|
2620
|
1070
|
1800
|
|
Polyethylene
|
0.90
|
1950
|
540
|
920
|
|
Polystyrene
|
1.06
|
2350
|
1120
|
2240
|
|
Rubber, butyl
|
1.07
|
1830
|
||
|
Rubber, gum
|
0.95
|
1550
|
||
|
Rubber neoprene
|
1.33
|
1600
|
||
|
Brick
|
1.8
|
3650
|
||
|
Clay rock
|
2.2
|
3480
|
||
|
Cork
|
0.25
|
500
|
||
|
Marble
|
2.6
|
3810
|
||
|
Paraffin
|
0.9
|
1300
|
||
|
Tallow
|
390
|
|||
|
Woods
|
||||
|
Ash, along the fiber
|
4670
|
|||
|
Beech, along the fiber
|
3340
|
|||
|
Elm, along the fiber
|
4120
|
|||
|
Maple, along the fiber
|
4110
|
|||
|
Oak, along the fiber
|
3850
|
|||
|
Human Body Tissues
|
||||
|
Soft Tissue
|
||||
Liquids |
||||
|
Substance
|
Formula
|
Density
(g/cm3) |
Velocity at 25°C
(m/s) |
-δv/δt
(m/sec °C) |
|
Acetone
|
C3H60
|
0.79
|
1174
|
4.5
|
|
Benzene
|
C6H6
|
0.870
|
1295
|
4.65
|
|
Carbon tetrachloride
|
CCl4
|
1.595
|
926
|
2.7
|
|
Castor oil
|
C11H10O10
|
0.969
|
1477
|
3.6
|
|
Chloroform
|
CHCl3
|
1.49
|
987
|
3.4
|
|
Ethanol amide
|
C2H7NO
|
1.018
|
1724
|
3.4
|
|
Ethyl ether
|
C4H10O
|
0.713
|
985
|
4.87
|
|
Ethylene glycol
|
C2H6O2
|
1.113
|
1658
|
2.1
|
|
Glycerol
|
C3H8O3
|
1.26
|
1904
|
2.2
|
|
Kerosene
|
0.81
|
1324
|
3.6
|
|
|
Mercury
|
Hg
|
13.5
|
1450
|
|
|
Methanol
|
CH4O
|
0.791
|
1103
|
3.2
|
|
Turpentine
|
0.88
|
1255
|
||
|
Water (distilled)
|
H2O
|
0.998
|
1496.7
|
-2.4
|
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