Sound through Metal ```Name: Lynne Status: educator Age: 40s Location: N/A Country: N/A Date: 2000-2001 ``` Question: How fast do sound waves travel through steel? Replies: There actually are two different speeds at which sound travels in steel. Longitudinal vibrations (pressure waves) propagate at around 6000 meters per second; transverse vibrations (shear waves) propagate at around 3000 m/s. (In air, by the way, only longitudinal vibrations propagate because air molecules don't hold onto each other tightly enough to propagate a shear wave.) Tim Mooney In solids, there are two kinds of acoustic waves -- longitudinal [the medium is vibrating in the direction of the acoustic wave] and transverse [the medium is vibrating at right angles to the direction of propogation]. The speed of sound is greater for longitudinal waves. The speed of propogation also depends on the frequency, but for audible sound [~20 cycles/sec. to ~20,000 cycles/sec.] it doesn't change too much. The trend in the speed of sound is: the harder the material, and the lower the density the faster the speed of sound: ```V(long)(m./sec) V(transv.)(m./sec) density(gm/ml) Fe(~steel) 5960 3240 7.9 Au 3240 120 19.7 Be 12830 8880 1.87 fused SiO2 5968 3764 2.2 ``` The numbers are from the Handbook of Chemistry and Physics, publ., Chemical Rubber Co. V. Calder The speed of sound in steel is about 5000 m/s (about 16000 ft/s). For comparison, the speed of sound in DRY air and water are about 340 m/s and 1500 m/s, respectively. The speed of sound in materials is dependent on temperature and other factors; the numbers above are for room temperature. AK Click here to return to the Physics Archives

NEWTON is an electronic community for Science, Math, and Computer Science K-12 Educators, sponsored and operated by Argonne National Laboratory's Educational Programs, Andrew Skipor, Ph.D., Head of Educational Programs.

For assistance with NEWTON contact a System Operator (help@newton.dep.anl.gov), or at Argonne's Educational Programs