# Sound Velocity of material

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 thunder clap, then divide by five. That gives you the approximate distance (in miles) away of the lightning. Divide by three for kilometers. Speed of sound very important for 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 plane longitudinal wave in bulk material.
• Vs = Velocity of 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 Berylium 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 Titaninum 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