photo album by robert mackay. sound waves are longitudinal waves
TRANSCRIPT
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Photo Album
by Robert MacKay
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Sound waves are longitudinal waves
• http://faraday.physics.utoronto.ca/IYearLab/Intros/StandingWaves/Flash/tunefork.html
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Audible range 20 – 20,000 Hzdecreases with age and damage
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Speed of sound in Air
• Depends of the air temperature. Higher air temperture the higher the speed.
• Depends of the molecular mass of air. Faster in helium, slower in air, and slower yet in Xenon.
skm
3
1about
T 0.6 331.5m/s)(in air in sound of speed C
or
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• During a lightning storm the thunder is heard 6 seconds after the flash. How far away was the lightning strike?
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• During a lightning storm the thunder is heard 6 seconds after the flash. How far away was the lightning strike?
2 km
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Speed of sound in Air
• Depends of the air temperature. Higher air temperture the higher the speed.
• Depends of the molecular mass of air. Faster in helium, slower in air, and slower yet in Xenon.
smi
or
51or ft/s 1100about
T 0.6 331.5m/s)(in air in sound of speed C
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• During a lightning storm the thunder is heard 10 seconds after the flash. How far away was the lightning strike?
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• During a lightning storm the thunder is heard 10 seconds after the flash. How far away was the lightning strike?
2 miles
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Speed of sound in solids
• Depends of the elasticity of solid. The stiffer the solid the higher the speed.
• Depends of the solid density. The lower a solid’s density the higher the speed.
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Beats
• The beat frequency is the difference between two frequencies.
21 fffBeat
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Beats are used in tuning
• when tuning a guitar a beat frequency of 3 Hz is heard when comparing the sound from the guitar to 256 Hz tuning fork.
• What is the guitar string’s frequency?
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Beats are used in tuning
• when tuning a guitar a beat frequency of 3 Hz is heard when comparing the sound from the guitar to 256 Hz tuning fork.
• What is the guitar string’s frequency? 253 or 259 Hz (can’t say for sure which one)
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Beats are used in tuning
• when tuning a guitar a beat frequency of 3 Hz is heard when comparing the sound from the guitar to 256 Hz tuning fork. The string is then slightly tightened and a beat frequency of 4 Hz is observed.
• What is the guitar string’s frequency now?
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Beats are used in tuning
• when tuning a guitar a beat frequency of 3 Hz is heard when comparing the sound from the guitar to 256 Hz tuning fork. The string is then slightly tightened and a beat frequency of 4 Hz is observed.
• What is the guitar string’s frequency now? 260 Hz
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Decibel Sound LevelDecibel Sound LevelDecibel Sound LevelDecibel Sound LevelSource of Sound Intensity (W/m^2) Sound Level dBJet at 30 m 1E+02 140
1E+00 120Disco Music 1E-01 110
1E-02 100Riveter 1E-03 90
1E-04 801E-05 70
Busy Street traffic 1E-06 601E-07 50
Quiet Radio 1E-08 401E-09 30
Whisper 1E-10 201E-11 10
Threshold of Hearing 1E-12 0
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it’s actually easyit’s actually easyit’s actually easyit’s actually easy• intensity 10 (101) louder 10 dB higher
• intensity 100 (102) louder 20 dB higher
• intensity 1000 (103) louder 30 dB higher
• intensity 10,000 (104) louder 40 dB higher
• intensity 1,000,000 (106) louder 60 dB higher
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