Sound waves

• Sound travels at about 340 meters per second in air at sea level at 20 degrees celsius
• Temperature and air pressure


  • Affect the speed sound can travel through air
  • Speed changes for different mediums
• In water, sound travels at 1,500 meters per second
• In some solids, sound can travel at up to 5,000 meters per second
• Particle arrangement in different states of matter

  • Solids: Particles fixed in rows, touching each other
  • Liquids: Particles remain touching, some gaps present
  • Gases: Particles far apart, occasionally colliding
• Distance between particles


  Speed at which sound travels
• The closer the particles, the faster sound travels
• The more densely the particles are arranged, the faster sound travels
• Temperature increases


  • Kinetic energy of particles increases
  • Particles collide more often
  • Sound travels faster
• Air pressure at sea level

  • Air particles more densely packed
  • Vibrations pass more quickly between particles
  • Sound travels faster
• When speed of sound changes, frequency remains the same but wavelength changes
• • As speed increases, wavelength increases
  • As speed decreases, wavelength decreases
• Measuring speed of sound

  1. Get someone to stand 400 meters away with stopwatch

  2. Bang drum and have partner start clock when they see it

  3. Partner stops clock when they hear the sound

  4. Repeat and take average

  5. Calculate speed = distance / time
• Measured speed of 333 m/s is close to but not exactly 340 m/s
• Possible reasons for difference: colder than 20 degrees, higher altitude, human error in stopwatch