1. Review of Sound Waves Waves move and carry energy Waves travel in a medium Waves are created when a source of energy causes a medium to vibrate Waves spread out as they move Waves have different sizes and shapes Waves pass through each other Waves continue in the medium until they reach a barrier Waves do not disappear at barriers (waves diffract around corners) Waves move and carry energy Waves travel in a medium Waves are created when a source of energy causes a medium to vibrate Waves spread out as they move Waves have different sizes and shapes Waves pass through each other Waves continue in the medium until they reach a barrier Waves do not disappear at barriers (waves diffract around corners)

2. Sound Sound is produced when objects vibrate It is a compression wave (or longitudinal wave) It needs something to travel through It travels through matter Sound is produced when objects vibrate It is a compression wave (or longitudinal wave) It needs something to travel through It travels through matter

3. Sound Waves Molecules in the air vibrate about some average position creating the compressions and rarefactions.

4. Longitudinal Wave wave particles vibrate back and forth along the path that the wave travels. Compressional Wave

5. Waves transfer energy without transferring matter. Frequency= waves/time

6. Frequency – How many wavelengths pass a point in a unit of time (the shorter the wavelength, the higher the frequency.) Image: scanned from Multimedia Concepts – James Schuman Sound Hz (Hertz) – 1 wavelength/sec. We hear it as pitch High frequency – high pitch Low frequency – low pitch