Sound Waves

1
Sound Waves
2
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
3
Refresh Types of Waves

• Longitudinal or compression vibrate parallel to
  velocity. ex. Sound
• Transverse vibrations perpendicular to
  velocity. ex. Light and water waves

4
Soundwave velocity

• Air (_at_ 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!
5
Reminder ?f?

• The velocity of a wave determines other
  properties as well f and ?.
• v ?
• V determined by medium

6
Visualizing Sound waves

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

7
Moving wave sources

• When a wave source moves, the wavelength and
  frequency becomes distorted.
• ? becomes a different length depending on the
  observers
• position.

?
8
Moving wave sources 2

• The faster the wave sources velocity, the more
  distorted the ?.

?
Source moving at the speed of the wave
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Moving wave sources 3
Doppler Effect apparent shift in frequency of a
wave caused by a moving wave source.
?
?
?
High frequency observed
Low frequency observed
10
The Sound Barrier

• 1st broken by Chuck Yeager (US Air Force test
  pilot) in the Glamorous Glennis a rocket plane
  named after his wife.

11
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.

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F-14 Tomcat and F-18 Hornet going Supersonic
MACH 1
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Video of sonic BOOM!!!

• 2006-6-5_Sonic_Boom.MPG
• SupersonicF14_2.mpeg

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Interference

• Destructive
• Constructive

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Interference2
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Resonance resound

• Just like constructive interference, resonance
  occurs when 2 vibrations occur in phase,
  producing a bigger vibration.
• http//video.google.com/videosearch?sourceidnavcl
  ienthlen-GBrlz1T4GZEZ_en-GBUS304US304qTacoma
  20Narrows20Bridgeum1ieUTF-8saNtabwv

17
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/sonbo
  at.html

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Echolocation - bats
See Ben Underwood