1. EQ: How do I define, describe and identify sound?
The Nature of Sound
EQ: How do I define, describe and identify sound?

2. EQ: How do I define, describe and identify sound?
A type of wave that is produced by a vibrating object and that travels through matter as a longitudinal wave.

3. EQ: How do I define, describe and identify sound?
Sound is a longitudinal wave that travels through a material medium, such as air. In this case the vibrating drum is causing the air particles to vibrate.
EQ: How do I define, describe and identify sound?
rarefaction
wavelength
compression

4. EQ: How do I define, describe and identify sound?
How do you make sound?
You force air up through your voice box, or larynx
Your larynx consists of two folds of tissue called vocal chords (like guitar strings)
EQ: How do I define, describe and identify sound?

5. How you speak ….
As the vocal chords move closer together, the air between them is compressed. As they move apart, the air spreads out, or rarefies. The air carries the longitudinal waves to other people’s ears and your own as well
EQ: How do I define, describe and identify sound?

6. Sound in Solids and Liquids
Sound travels through solids and liquids
Example- knocking on a door
When you knock, the particles of the door vibrate
The vibration creates sound waves that travel through the door
When the sound waves reach the other side, the same vibrations make sounds waves in the air.
EQ: How do I define, describe and identify sound?

7. EQ: How do I define, describe and identify sound?
Sound in Space
Sound can only travel if a medium is available to transmit the compressions and rarefactions. In outer space, there are no molecules so there is nothing for the sound to travel through and so there is no sound. Space is a vacuum-A space containing no particles of matter. -

8. The Speed of Sound
It depends on three properties of the medium it travels through
Elasticity
Density
Temperature
EQ: How do I define, describe and identify sound?

9. Elasticity
The ability of a material to bounce back to its original shape
Solid materials are usually more elastic
Sound travels better in mediums that have a high degree of elasticity because when the particles are compressed, they quickly spread out again – increase speed of sound
Which has the most elasticity, solid, liquid or gas?
EQ: How do I define, describe and identify sound?

10. Density How much matter, or mass, there is in a given space or volume
The denser the medium, the more mass it has. The particles in a dense material travel slower than in a less denser material, therefore, sound will move slower through more dense materials.
EQ: How do I define, describe and identify sound?

11. Temperature
In a given medium, sound travels slower at lower temperatures and faster at higher temperatures.
At 20 C, speed of sound in air is about 340m/s, at 0 C the speed is 331m/s
At higher altitude the air is colder, so sound travels slower at higher altitude
EQ: How do I define, describe and identify sound?

12. Moving Faster Than Sound
October 14, 1947, Chuck Yeager broke the sound barrier
October 15, 1997, Andy Green broke the speed of sound on the ground with his jet powered car called Thrust.

13. Class Work and Homework
EQ: How do I define, describe and identify sound?
Fill In
What did I learn
Confused
Say
Read pages O 40 – O 44, Answer questions 1- 4 on 0 44
(Pay special attention to figure 4, page 42)
2-1, Worksheet answer all questions