96 



SOUND 



7. Name some bodies whose vibrations can be seen. Name 

 some whose vibrations can be felt. Why can we not see the 

 vibrations in all masses ? 



8. Where is sound located ? Is there sound in a vibrating body 

 or in the air ? 



SECTION II 

 TRANSMISSION OF SOUND WAVES 



107. Different Media Sound waves may travel 



through other substances than air, though they usually 

 pass through the air a short distance anyway, before 

 reaching the ear. In general, solids carry sound waves 



FIG. 72 



better than liquids, and liquids better than gases. That 

 sounds are sharper under water is known to every boy 

 who swims, and we know that sound waves come 

 through the iron rails of a track much faster than 

 through the air. 



Experiment 83. Listen at one end of a log or an iron rail while 

 some one scratches the other end with a pin. Do the same with 

 several solids. 



