Sound Waves

1
Sound Waves

• You Have to Hear This!!!!

2
Producing a Sound Wave

• Like all waves, sound waves are produced by a
  vibration.
• A tuning fork vibrates to produce a sound.
• A guitar string vibrates to produce a sound.
• Your vocal cords vibrate to produce a sound.
• A tree that falls in the woods causes a vibration
  and produces a sound even if no one is around to
  hear it!!!!!!!

3
Properties of Sound Waves

• Sound Waves are Longitudinal Waves.
• As the fork moves forward and back it alternately
  compresses and then decompresses the air (or
  whatever medium it is traveling through).
• From above the source it looks
• more like this

4
Properties of Sound Waves

• Sound Waves are Mechanical Waves
• This means they MUST have a medium (matter) to
  travel.
• This means sound waves CANNOT travel through
  empty space ( a vacuum).

5
Properties of Sound Waves

• All sound travels at the same speed in the same
  medium.
• This speed is called the speed of sound.
• The speed of sound in air is 343 m/s (767 mph)
• The speed of sound in water 1433 m/s (3206 mph)
• The speed of sound in concrete 3400 m/s (7606
  mph)
• The speed of sound in steel 6100 m/s (13645 mph)

6
Properties of Sound Waves

• The speed of sound is also affected by
  temperature.
• Basically, the higher the temperature the faster
  sound travels.
• As an equation this looks like this
• vsound 331 0.6Tc

7
The Doppler Effect

• Whenever a source of sound is moving, the pitch
  you hear depends on whether the sound source is
  moving towards you or away from you.