Title: The Nature of Sound
1The Nature of Sound
- EQ How do I define, describe and identify sound?
2Sound
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.
3Sound 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
4How 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?
5How 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 peoples ears and
your own as well
EQ How do I define, describe and identify
sound?
6Sound 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?
7Sound in Space
EQ How do I define, describe and identify
sound?
- 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. - -
8The 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?
9Elasticity
- 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?
10Density
- 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?
11Temperature
- 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?
12Moving 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.
13Class 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