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Explore the properties of sound waves, including the speed of sound in different mediums, the concept of beats in tuning, and the measurement of sound intensity in decibels. Discover how sound waves behave and how they can be affected by factors like temperature and density.
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Photo Album by Robert MacKay
Sound waves are longitudinal waves • http://faraday.physics.utoronto.ca/IYearLab/Intros/StandingWaves/Flash/tunefork.html
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.
During a lightning storm the thunder is heard 6 seconds after the flash. How far away was the lightning strike?
During a lightning storm the thunder is heard 6 seconds after the flash. How far away was the lightning strike? 2 km
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.
During a lightning storm the thunder is heard 10 seconds after the flash. How far away was the lightning strike?
During a lightning storm the thunder is heard 10 seconds after the flash. How far away was the lightning strike? 2 miles
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.
Beats • The beat frequency is the difference between two frequencies.
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?
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)
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?
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
it’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