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Chapter 21 Quest
Chapter 21 notes compiled for the quest
Question | Answer |
---|---|
all sounds are created by _____ | vibrations |
what are vibrations? | the complete back and forth movement of an object |
what is the most common sound medium? | air |
what does the speed of sound depend on | the medium |
how does temperature affect sound? | high temp=faster speed |
how high or low a sound seems | pitch |
what is the human range of sounds we can hear? | 22-20,000 Hz |
the apparent change in frequency of sound caused by the motion of either the listener or the sound source | Doppler effect |
in a moving sound source, which wave do waves move | in the direction of the object |
in a moving sound source, what does the person in front hear, and what does the person behind hear? | in front, high, in back, low |
why? | after the objects passes, the waves are moving in the opposite direction than the moving sound waves |
measure of how well a sound can be heard | loudness |
the common unit to express loudness | decibel |
what is the symbol for decibel? | dB |
on an oscilloscope, what parts represent rarefactions and compressions? | crests=compressions, troughs=rarefactions |
why do we use oscilloscopes to see sound waves? | they are graphed as transverse waves, and you can quickly see the amplitude and frequency |
a reflected sound wave | an echo |
the use of reflected sound waves to find an object | echolocation |
what can sonar do? | help avoid icebergs, map ocean floor |
what can see inside a body without surgery? | ultrasonography |
to faster than the speed of sound, what must happen? | breaking of the sound barrier |
sound heard when shock wave reaches ears | sonic boom |
outer edges combine with constructive interference to form shock wave | |
pattern of vibration that looks like it is standing still | standing wave |
the lowest resonant frequency is called the: | fundamental |
high resonant frequencies are called: | overtones |
what do standing waves do to sound? | amplify it |