Book+3+Chapter+2.1


 * Chapter 2: Sound**
 * I. The Nature of Sound**
 * A. Sound is disturbance that travels through a medium as a longitudinal wave.**
 * 1. Begins with a vibration**
 * 2. Vibrations disturb nearby air particles**
 * 3. Particles moving cause compressions and rarefactions - long waves**
 * 4. Carry energy through a medium without moving the particles of the medium along the way**
 * 5. Each particles of the medium vibrates as the disturbance passes**
 * 6. Disturbance reaches your ears = Sound**
 * 7. Common medium for all sound...AIR**
 * B. Sound waves reflect off objects, diffract through narrow openings and around barriers and interfere with each other.**
 * 1. Echo - reflected sound wave.**
 * i. Sound waves may reflect when they hit a surface**
 * ii. Harder and smoother the surface = stronger reflection**
 * 2. Sound waves can diffract or bend around corners**
 * i. Do not always travel in straight lines**
 * 3. Sound waves may meet and interact with each other = interference**
 * i. Can be constructive or destructive**
 * C. Speed of sound - depends on the elasticity, density and temperature of the medium through which sound travels**
 * 1. Elasticity - the ability of a material to bounce back after being disturbed**
 * i. Depends on how well the medium's particle bounce back**
 * ii. More elastic a medium = faster sound travels in it.**
 * a.) Travels better in solid than liquids or gasses**
 * b.) gasses are not very elastic**
 * c.) Sound travels slowly in gasses**
 * 2. Density - how much matter or mass, there is in a given amount of space or volume.**
 * i. Denser the medium, the more mass it has in a given volume**
 * ii. sound travels more slowly in denser materials**
 * 3. Temperature**
 * i. Sound travels more slowly at lower temperatures than at higher ones.**
 * ii. Air is colder at lower altitudes**
 * a.) sound travels more slowly at higher altitudes**
 * b.) 1947 - Chuck Yeager - broke sound barrier**


 * Quiz**
 * 1. increase speed**
 * 2. decrease speed**
 * 3. increase speed**
 * 4, Sound is a disturbance that travels through a medium as a longitudinal wave**
 * 5. yes - humans have broken the sound barrier**
 * 6. echo**
 * 7. diffraction**
 * 8. interference**
 * 9. density**
 * 10. elasticity**


 * Study Guide**
 * 3. except: elasticity**
 * 11. longitudinal**
 * 16. true**
 * 20. false - reflected**