Sound

Sound

1. form of energy that is transferred from one point to another as a longitudinal wave

   • longitudinal waves
     • amplitude, frequency, wavelength
     • compressions
       • regions where air pressure is higher than surrounding air pressure
     • rarefactions
       • regions where air pressure is lower than surrounding air pressure
     • pressure-distance graph
     • displacement-distance, displacement-time graphs

2. produced by vibrating sources placed in a medium

   • medium usually air, but can be any gas, liquid or solid
     • speed of sound in gas < liquid < solid
   • object vibrating in air causes layers of air particles around it to be displaced
     • displacement of air particles causes sound waves to travel
   • air
     • 300 m/s
   • water
     • 1500 m/s
   • iron
     • 5000 m/s
   • granite
     • 5400 m/s

3. echo

   • repetition of a sound due to reflection of sound
   • sound is reflected off hard, flat surfaces
     • similarly laws of reflection of light
   • measure large distances, detect location of objects

4. pitch

   • frequency of a sound wave
     • higher frequency, higher pitch

5. loudness

   • amplitude of a sound wave
     • larger amplitude, louder sound