Transcript speed of sound

SAT VOCAB TWO
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Audible (adj.) able to be heard
Oscillate (v.) to sway from one side to another
Dissonance (n.) lack or harmony or consistency
Undulate (v.) to move in waves
SAT VOCAB TWO
Now that we are through with waves, we are
moving onto the topic of sound. Sound waves are
waves that are _______________. The reason we
can hear them is that the waves make our ear drum
___________________ because the wave
_______________ in the ear canal. When we
hear something that is not of a pleasing quality, it
creates ________________ and we think of it as
noise.
Sound
Chapter 12
REVIEW
 Waves
transport ENERGY, not
matter.
 Waves are mechanical (matter)
or non-mechanical (no matter).
Transmission of
 Sound is mechanical.
Sound
 Light is non-mechanical.
SOUND WAVES
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Sound waves are Compressional waves.
The vibrations of the molecules are parallel to the
direction of the wave.
Produced by the compressions and rarefactions of
matter.
SOUND WAVES
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Sound is produced by a vibrating object.
As one individual particle is disturbed, it transmits the
disturbance to the next interconnected particle.
This disturbance continues to be passed on to the next
particle.
The result is that energy is transported without the actual
transport of matter.
SOUND WAVES
LABEL YOUR DIAGRAM
SOUND WAVES
WHAT DO SOUND WAVES
LOOK LIKE
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Visualizing Sound
SPEED OF SOUND
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Speed depends upon how fast one particle
can transfer its motion to another particle.
Speed of sound depends on the
Elasticity
 Medium (Density)
 Temperature
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Why?
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Sonic boom
SPEED OF SOUND
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Speed of Sound: depends on the elasticity, density and
temperature.
Elasticity – the ability of an object to bounce back to its
original shape. Sound travels faster in more elastic objects.
Typically gases are the least elastic, liquids are next and
solids are the most elastic.
Density – generally speaking, in material of the same state
of matter (solid, liquid or gas) the denser the medium the
slower the sound travels. Sound travels slower in lead
than it does in steel.
Temperature – generally speaking the higher the
temperature, the faster the speed of sound.
SPEED OF SOUND
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Speed of Sound – on average
Air is 767 mph (346 m/s) – about 1 mile per 5s.
 Water is 3,315 mph (1,482 m/s) about 1 mile per
1.1s.
 Steel is 13,330 mph (5,960m/s) about 1 mile per
0.27s or
3.7mile per 1s.
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SPEED OF SOUND
SPEED OF SOUND
BREAKING THE SOUND
BARRIER
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Chuck Yeager – first man to fly faster than the
speed of sound
Andy Green – first man to drive a land vehicle
faster than the speed of sound.
October 14, 1947 –
in X1 “Glamorous
Glennis”
October 15, 1997 –
in SuperSonic Car
“Thrust SSC”
763 MPH
HOW
WE
HEAR
HOW WE HEAR
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When a sound wave reaches the ear, a series
of high and low pressure regions hit the
eardrum.
The arrival of a compression or high
pressure region pushes the eardrum inward;
the arrival of a low pressure region serves to
“pull” the eardrum outward.
The continuous arrival of high and low
pressure regions sets the eardrum into
motion.
HOW WE HEAR
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Auricle (Pinna-the ear
flap) – used to focus the
sound waves into the ear
canal
Ear Canal (Auditory
Canal) – focuses the
sound onto the ear drum.
Ear Drum (Tympanic
membrane) – Sound
starts the ear drum
vibrating.
HOW WE HEAR
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Ear Drum vibrates
Three smallest bones vibrate, one
after the next
 Hammer (Malleus) is
touching the ear drum &
vibrates first.
 Next is the Anvil (Incus).
 Last is the Stirrup (Stapes).
 Eustachian Tube: tube that
connects the middle ear
with the throat. This allows
the pressure on both sides of
the ear drum to equalize.
HOW WE HEAR
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The Stirrup vibrates the oval window of the cochlea.
Cochlea is a long fluid filled tube, folded in half and
thencoiled up like a snail shell. The entire inner surface is
lined with cilia, little hairs.
Once cilia are vibrated, the attached nerves are
stimulated & send signal to the brain.
Balance is achieved by
the semicircular canals.
• Three canals in three
different planes are able
to determine the body’s
position in space .
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HOW WE HEAR
Need to know these structures & their function: Outer Ear, Middle Ear, Inner Ear,
Auricle, Ear canal, Ear drum, Hammer, Anvil, Stirrup, Oval Window, Cochlea,
Auditory Nerve, Semicircular Canals, Eustachian Tube.
PROPERTIES OF SOUND
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Intensity – the amount of energy the wave
carries; sound level is measured in decibels
(dB); it influences how far away a sound can be
heard.
PROPERTIES OF SOUND
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Loudness – how we perceive intensity.
depends on the amplitude.
 Larger amplitude means more pressure.
 Remember: amplitude is a measure of the
amount of energy in the wave.
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PROPERTIES OF SOUND
PROPERTIES OF SOUND
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Frequency – the number of wavelengths that pass
a particular point (vibrations) per second, Hz.
 Human Hearing – between 20 Hz – 20,000 Hz.
 Below 20 Hz is called infrasound.
 Above 20,000 Hz is called ultrasound.
Pitch - determined by frequency; the highness or
lowness of sound.
 high frequency yields high pitch sounds
 Low frequency yields low pitch
PROPERTIES OF SOUND
Low Pitch
High Pitch
Low to High Frequency
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Pitch and Frequency
Resonance – when the frequency of sound
matches the natural frequency of an object.
TACOMA NARROWS BRIDGE
COLLAPSE
Nov. 7, 1940
Galloping Gertie
On a day of rather high winds,
Gertie took on a 30-hertz
transverse vibration (like sending
waves down a rope by moving the
end up and down) with an
amplitude of 1½ feet! It later took
on a twisting motion of about 14
hertz and quickly tore itself in two.
PROPERTIES OF SOUND
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Sound waves can be
reflected.
A reverberation is
perceived when the
reflected sound
wave reaches your
ear in less than 0.1
second after the
original sound wave.
An echo takes
longer.
PROPERTIES OF SOUND
Doppler effect
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Variation in the perceived
pitch of a sound due to a
moving sound source.
“bunches up” in front of
the source
Spreads out behind the
source
PROPERTIES OF SOUND
Doppler Effect
PROPERTIES OF SOUND
A sonic boom is
the sudden onset
and release of
pressure after the
buildup by a sound
shock wave.
Sonic Boom
This picture shows a sonic boom created by the
THRUST SSC team car as it broke the land speed
record and broke the sound barrier on land.
MUSIC VS NOISE
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Music is sounds that are deliberately used in a
repeated pattern.
Noise has random patterns and pitches.
Sound Applications
MUSIC VS NOISE
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Materials have their own natural frequencies.
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Examples: guitar strings, wine glass, other
musical instruments
Resonance is the ability of an object to vibrate
by absorbing energy at its natural frequency.
Wine glasses
USING SOUND
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Acoustics is the study
of sound.
Sound is studied so that
concert halls,
classrooms, theaters,
etc. can be constructed
to minimize
destructive
interference and
diffuse reflection.
ECHOLOCATION
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The use of sound waves and echoes to determine where
objects are in space.
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Bats send out sound waves using their mouth or
nose.
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When the sound hits an object, an echo comes back.
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They can tell the distance between themselves and the
object .
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They can identify an object by the sound of the echo.
ECHOLOCATION
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They can even tell the
size, shape and texture
of a tiny insect from
its echo.
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Most bats use
echolocation
to navigate in the
dark and find food.
VIDEO
SONAR
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Sonar - Sound Navigation and Ranging
Sonar uses sound waves to 'see' in the water
It is helpful for exploring and mapping the
ocean because sound waves travel farther in the
water than do radar and light waves.
ULTRASOUND
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a device that uses high frequency sound waves
to create an image of some part of the inside of
the body, such as the stomach, liver, heart,
tendons, muscles, joints and blood vessels.
BIOACOUSTICS
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Bioacoustics is a branch of science concerned with
the production of sound and its effects on living
systems.
Animals that generate infrasound include elephants,
whales, alligators, hippos, rhinos, giraffe, lions, tigers
and several birds.
Animals that generate ultrasound include dolphins,
bats, many birds and insects.
CYMATICS
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from Greek meaning “wave”.
Typically a surface is vibrated and regions of
maximum and minimum displacement are made
visible in a thin coating of particles, paste or
liquid.
Different patterns emerge as the surface
vibrates.
Cymatics