Transcript Chapter 21 Section 1

Vibration
A vibration is the
complete back-andforth motion of an
object.
One common
characteristic of sound
(VIBRATION)
Sound Wave
Sound Wave
A longitudinal wave
that is caused by
vibrations and that
travels through a
medium.
Does Air travel with sound?
No no no no
no
!!!!!!
It does not
How fast does sound travel?
Depends on the medium it’s
traveling through.
Air (0°C)
Air(20°C)
Air (100°C)
Water (20°C)
Steel (20°C)
331 m/s
343 m/s
366 m/s
1,482 m/s
5,200 m/s
Other Mediums Sound can travel
Through?
Other than air
sound can travel
through liquids
and solids.
Temperature affects sound.
Warm : Speeds up
Cold : Slows down
So sound speed depends on
medium and temperature,
to name a few.
Medium
• Medium
A physical environment in
which a phenomena
occur.
Here sound can’t travel
outside this man’s space
suit..No medium to travel
through.
Collects
sound
waves
Small
organs
increase the
size of the
vibrations.
Changes
the
vibrations
into
electrical
signals
that your
brain
interprets
as sound.
Tinnitus
•
TinnitusHearing loss. Causes
ringing in the ear.
Once hearing loss is
established the ear can
not repair itself.
You can prevent hearing loss
by
1. Wearing ear protectors
2. Walking away from the
loud sound.
When a tree falls in the forest
and no one is around
• Yes it produces a
sound even though
your not around to
hear it.
Pitch
NO!
NO!
Pitch
PitchA measure of how
high or low a
sound is perceived
to be, depending
on the frequency
of the sound wave.
Ultrasonic Frequency
Ultrasonic Frequency
Sounds that are too high
for people to hear.
Above 20,000 Hz
Doppler Effect
• Doppler Effect
An observed
change in the
frequency of a
wave when the
source or
observer is
moving.
How pitch and Frequency are related.
The lower the pitch the lower the frequency.
The higher the pitch the higher the frequency.
Loudness
Loudness
A measure of how
well a sound can be
heard.
Yelling won’t get it
there any faster.
Amplitude
The harder you strike the
drum the louder the bang.
Amplitude- The largest
distance the waves vibrate
from their rest position.
Thus the greater the
amplitude the more energy
the sound wave has. Thus
it will sound louder.
Decibel- (dB)
The most common unit used to
measure loudness. Expressed:
120 db is the threshold of pain
dB
Decibel
Oscilloscope
A device that graphs
sound waves
Sound waves are longitudinal but the
oscilloscope graphs them as
transverse