12/15/08

Post date: Dec 15, 2008 3:0:12 AM

Bell Activity: Think of a question to ask about waves to ask before our mini-quiz.

• • Waves mini-quiz

  • Sound

    • Is an example of a longitudinal wave, meaning the particles in a sound wave move parallel to the wave

    • What's waving?

      • The air pressure is changing, getting higher and lower than "normal" air pressure

      • Equilibrium in a sound wave is what the pressure in that area would be without a sound wave

      • The peaks represent the highest pressure, where the air has been squeezed together. We call this compression.

      • The troughs represent the lowest pressure, where the air has been stretched out. We call this rarefaction.

    • Sound behaves like any other wave

      • Interference - can hear two different sounds at the same time

      • Reflection - echoes, sonar

      • Refraction - sound is bent upward on hot, sunny days

      • Diffraction - sound can go around a corner and still be heard

      • The wave equation still applies

      • The speed of sound depends on what it's traveling through

        • Moves faster through warmer air

          • v = 331 + 0.6*T

        • Moves faster through liquids than gases, and fastest through solids

  • Do page 309: 1-4 for tomorrow