Name: Maria G.
Status: educator
Age: 40s
Location: N/A
Country: N/A
Date: 2000-2001
Question:
Does a sound travel best through solids, liquids. or
gases? How can I demonstrate it to my students?
Replies:
Sound travels best through solids.
As for amount of the signal that gets through, a technique used by hobos is
a good example. A train can be heard from a much greater distance by
placing one's ear to the rail than by listening through the air. Place your
ear to the end of a long table. Lightly tap the table. You will hear the
tapping much more clearly through the table than through the air.
As for speed of sound, one experiment involves resonance frequencies.
Support a metal shaft of significant length at either end. Aluminum will
work, but the shaft cannot be hollow. It must be solid. Strike the shaft
and measure the frequency of the resulting resonance frequency. The
wavelength when the sound is within the metal will be twice the length of
the shaft: a standing wave with both ends held still. The frequency within
the shaft will be the same as the frequency within the shaft. Multiply
frequency (in cycles per second) by wavelength (meters per cycle) to yield
the wavespeed within the shaft in meters/second.
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