sound

• wave?


  disturbance that transmits energy through matter
• mechanical waves?


  require a meduim
• longitudinal

  • particles parallel to wave motion
  • e.g sound wave
  • have compressions(high pressure areas) and rarefactions(low pressure area)
• transverse wave


  particles perpendicular to wave motion

  e.g light wave
• experiment to prove that sound cant travel in vaccum

  1. place an electrical bell in a bell jar
  2. pump out all of the air
  3. turn on bell
  4. u wont hear sound
  5. shows u need medium
• sonic waves


  in human range 20 Hz to 20KHz
• ultra sonic


  more than 20KHz

  used in medical fields
• infrasonic


  below 20Hs

  used by elephants
• what does loudness depend on

  amplitude(height)
• what does pitch depend on


  frequency(no of waves per sec)
• echo?


  repetition of sound due to reflection

  its formed if the reflection of sound is heard after 0.1 second
• sound travelling through different stuff

  air:343m\s

  water:1550m\s

  steel:5800m\s

  gas:300m\s

  solid:3000m|s
• compression and rarefaction?

  compression: high pressure regions

  rarefaction: low pressure regions
• formulae?


  • speed(v)=frequency(f)X wavelength
  • speed= distanceX 2 \ time