1. Sound and the Doppler Effect

2. Sound All sounds are produced by the vibrations of material objects They are compressional waves carried by a medium (air, water, solid) The molecules vibrate to the sound and transfer it to other molecules via collisions

3. Sound The frequency of a sound wave is described by its pitch. High pitch = high frequency, low pitch = low frequency Humans can hear between 20Hz to 20000Hz.

4. Sound The speed of a sound wave is mostly dependent on the density of materials Sound travels much faster in water than in air, and even faster through solids than water. Sound does not travel well through rubber.

5. Sound

6. Speed of Sound

7. Doppler Effect Sources of waves, whether light or sound, can be moving. For a sound wave, this movement will cause a change in the frequency heard from the source. The siren of a firetruck approaching you will have a higher frequency than if the firetruck is at rest. The firetruck moving away from you will have a lower frequency than at rest as well.

8. Doppler Effect

10. Try some of these problems: Homework will be assigned next class: the printers are broken 