1. Unit 5 Ch. 21 What is Sound?

2. You are in a restaurant, and without warning, you hear a loud crash. A waiter dropped a tray of dishes. What a mess! But why did dropping the dishes make such a loud sound?

3. “Today, I can describe how sound is produced and how it travels.” You Will Learn to: Describe how vibrations cause sound. Explain how sound is transmitted through a medium.

4. Characteristics of Sound All sound is created by vibrations. Sound travels via (by) longitudinal waves (compressions and rarefactions … particles of the medium vibrate parallel to the direction of the wave) Sound waves require a medium through which to travel.

5. How do vibrations cause sound? Vibration is the complete back-and-forth motion of an object. Sound waves travel in all directions away from their source. Sound is transmitted through the vibrations & collisions of particles.

6. Media and Sound Sound waves require a medium through which to travel. Most sounds travel through air at least part of the time, but it can travel through other medium such as glass, water, and metal. Media allows sounds to reach ears and be detected. No sound can be made in a vacuum because there are no particles to vibrate.

7. Based on what you have learned about sound, why do you think dropping the dishes made such a loud sound?