Introduction to sound for Middle School Students

1. 8th Grade Science
Prentice Hall
Sound and Light

2. 
If a tree falls in the woods and no one
hears it was there a sound?
Yes!
Sound is a disturbance that travels
through a medium in longitudinal waves.
What is Sound?

3. 
With a vibration.
There is a disturbance of a medium.
In the case of the guitar, there is a
disturbance air molecules
How does a soundwave
begin?

4. 
Moves particles in a medium
without moving the particles
along.
Common particle is air, but sound
can travel through water, and
wood. (solids and liquids)
How does sound travel?

5. 
Reflection: echo
Diffraction: Sound out in the hall
is heard in the room.
Interactions of sound
waves

6. 
Sound waves can interact.
Constructively and Destructively
Interference

7. 
Air travels at about 343 m/s
But speed of travel of sound
depends on three things:
Elasticity, density and temperature
of the medium.
Speed of sound

8. 
The ability of a material to bounce
back after being disturbed.
Rubber bands bounce back
quickly.
The more elastic a medium the
faster sound travels. Solids are
more elastic than liquids and gases.
What Is Elasticity?

9. 
How much matter there is in an
object.
Sound travels more slowly in
denser mediums. For example,
sound travels slower in lead than
iron.
Density

10. 
In a given medium, sound travels
more slowly at lower temperatures
than at high temperatures.
Why? At low temperature, the
particles move more slowly.
Temperature and sound
travel

11. 
Read pages 36-41
Complete Review questions
covering this subject
Assignment