CHAPTER 12: SOUND

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CHAPTER 12 SOUND

• SECTION 12.1
• SOUND WAVES

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WHAT IS SOUND?

• A type of mechanical wave (Do you remember which
  type?) produced by rarefaction and compression of
  matter.
• The velocity of sound in air depends on the
  temperature of air.
• Sound travels at a speed of 343 m/s at sea level
  and 200C

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WHAT IS SOUND?

• The velocity of sound is greater in liquids and
  solids than in gases.
• There is no sound in a vacuum because there are
  no particles to collide with!

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PROPERTIES OF SOUND

• Doppler Shift the frequency of an object is
  higher moving toward you than when it moves away
  when the pitch is lower.
• Pitch the frequency of waves
• Octave 2 notes with a 21 frequency

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PROPERTIES OF SOUND

• Loudness dependent on the amplitude of the
  pressure variation of the wave.
• Decibel measures loudness
• Logarithmic scale
• Every change in 20 dB changes the pressure by a
  factor of 10.
• Resonance vibrations at the same frequency.