Topics for today:

  • Start out with a short in-class quiz.

  • Energy and Power discussion (cont.)
    • Energy units: joules, calories, kilowatt-hours, therms.
    • Power units: watts, horsepower.
  • Wave motion in the air.
    • Sound waves can be viewed as localized particle displacement, or as a pressure disturbance.
    • Sound waves in air are longitudinal: the particle motion is forward-backward in the direction the wave is propagation.
    • Sound waves have a speed, and a physical repetition period and wavelength.
      Speed of sound c = frequency times wavelength.
    • Sound waves are susceptible to propagation, reflection, absorption, refraction, and diffraction.

Topics for the next lecture:

  • Read chapters 6 and 8 from the textbook.
  • Interference and beating.
  • Harmonics and spectrum.
  • Sound levels and the decibel.