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Sound Waves

Sound Waves. Refresh: Types of Waves. Longitudinal or compression – vibrate parallel to velocity. ex. Sound Transverse – vibrations perpendicular to velocity. ex. Light and water waves. Soundwave velocity. Air (@ 20 0 C) – 343 m/s Water – 1482 m/s Seawater – 1522 m/s

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Sound Waves

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  1. Sound Waves

  2. Refresh: Types of Waves • Longitudinal or compression – vibrate parallel to velocity. ex. Sound • Transverse – vibrations perpendicular to velocity. ex. Light and water waves

  3. Soundwave velocity • Air (@ 200 C) – 343 m/s • Water – 1482 m/s • Seawater – 1522 m/s • Steel – 5960 m/s (trains) • 1 mile = 1600m Denser = Faster! What type of relationship is this? Directly Proportional of course!

  4. Reminder: υ=fλ • The velocity of a wave determines other properties as well… f and λ. • v = ? • V determined by medium

  5. Visualizing Sound waves • Sound waves create rings that move away from the wave source. • Each ring has a λ from the next ring • λ is equal to all others if the source is stationary.

  6. Moving wave sources • When a wave source moves, the wavelength and frequency becomes distorted. • λ becomes a different length depending on the observer’s position. υ

  7. Moving wave sources #2 • The faster the wave source’s velocity, the more distorted the λ. υ Source moving at the speed of the wave

  8. Moving wave sources #3 Doppler Effect – apparent shift in frequency of a wave caused by a moving wave source. υ λ λ High frequency observed Low frequency observed

  9. The “Sound Barrier” • 1st broken by Chuck Yeager (US Air Force test pilot) in the Glamorous Glennis… a rocket plane named after his wife.

  10. The “Sound Barrier” • A sonic “BOOM” is an extreme example of Doppler • The wave source moves faster than the wave of sound • A “cone” of compression results as the air tries to get out of the way. • Usually, a “cloud” forms as water vapor condenses under the extreme pressure. υ

  11. F-14 Tomcat and F-18 Hornet going Supersonic – MACH 1

  12. Video of sonic BOOM!!! • 2006-6-5_Sonic_Boom.MPG • SupersonicF14_2.mpeg

  13. Interference • Destructive • Constructive + = = +

  14. Interference#2

  15. Resonance – “resound” • Just like constructive interference, resonance occurs when 2 vibrations occur in phase, producing a bigger vibration. • http://video.google.com/videosearch?sourceid=navclient&hl=en-GB&rlz=1T4GZEZ_en-GBUS304US304&q=Tacoma%20Narrows%20Bridge&um=1&ie=UTF-8&sa=N&tab=wv#

  16. Use of sound technology • Thunder and lightning! 5 sec ~ 1 mile. • Sonar – using the echo of a soundwave to determine distance and position of objects. http://earthguide.ucsd.edu/images/aldemo/swf/sonboat.html

  17. Echolocation - bats See: Ben Underwood

  18. Refresh: Vibrations • A “vibration” can be compared to a pendulum swinging back and forth as its energy is transformed from KE to PE to KE. PE max, KE min PE max, KE min KE max, PE min

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