Transcript
8/2/2019 Nature of Sound Waves
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NATURE OF SOUND WAVES
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OBJECTIVES
At the end of the lesson, you should be able to:
a. Explain how sound waves are produced,
transmitted, and propagated;b. Perform activities related on the nature of sound
waves;
c. Appreciate the things around us which act as media for sound waves; and
d. Point out the importance of sound waves.
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SOUND WAVES
Sound waves are produced by vibrating
objects.
How are sound waves produced?
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This refers to the to-and-fro oscillation of molecules as a disturbance travels
through a medium.
VIBRATION OF MOLECULES
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WHEN WE SAY OSCILLATION,
Consider a pendulum..
How does a pendulum move?
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The Grandfather’s Clock is
also a good example of a
pendulum.
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Like the pendulum, vibrating molecules also
move back and forth; thus, disturbing theother molecules.
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RECALL THE TYPES OF WAVES
Transverse Wave
Longitudinal Wave
Under what type of wave aresound waves classified?
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Molecules of the transverse wave move up and
down.
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Molecules of the longitudinal wave move back
and forth.
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Sound waves are considered longitudinal waves.
To illustrate it further, moving a slinky back and
forth is a perfect example of showing longitudinal
waves.
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Since sound waves are longitudinal waves, the
vibration of the molecules will be parallel tothe direction of the wave propagation.
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How is your voice produced?
The sound that comes from your mouth when
you speak is produced by the vibrations of twothin sheets of membrane which is called your
vocal cords.
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What is the key word on howsounds are produced?
Vibration (of molecules)!
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How are sound waves transmitted?
Sound waves are transmitted thru a medium
or media.These include gas (air), liquid (water), and
solid.
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Will there be a difference on how
sound waves will travel on thethree media?
Assign a member of your table to put his/her
ear against the end of a tabletop. Another one
has to gently tap the other end of the table with a ruler or pencil.
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Are all solids good transmitters of
sound waves?
Strike the tuning fork and bring its handledown on the cloth. Then strike again the
tuning fork and place its handle on the
tabletop. Which is louder?
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Solids that are not good in transmitting sound
do not possess much elasticity; therefore they are poor media for sound transmission.
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Generally, liquids are better conductors of
sound than gases.
Which of the two is a better sound
transmitter: liquids or gases?
Example
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So why is liquid a better sound
transmitter than gas, and solidbetter than the liquid?
Arrangement of molec ules i n solids, liquids,
and gases
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How sound waves travel
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That is why you need to speak louder as you
climb a mountain..so that you can be heard.
Which of the three is the best fortransmitting sound?
Solid/s!
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How are sound waves propagated
or spread?
As the sound waves are transmitted in solids,
liquids, and gases, sound waves also spread or propagate at the same time.
So when they spread, molecules disturb other molecules.
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And because sound waves are longitudinal
waves, this disturbance happens continuously
until the air molecules (sound waves) strike
your eardrums, making it vibrate.
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And thru the parts of your ear, impulse is sent
to your brain which is then interpreted assound.
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Why do you hear sounds?
Because of the propagation or
spreading of sound waves!
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Can sound waves travel thru a
vacuum?
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What are the practical
importances of sound waves?
Bats rely on sound waves to locate their prey and avoid
predators.
Bats use echolocation to locate and catch their prey. When bats fly, they produce a constant stream of high-pitched sounds that only bats are able to hear. When the sound waves produced by these sounds hit an insect or other
animal, the echoes bounce back to the bat, and guide them
to the source.
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IN GENERAL..
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Let us see to it that before wetransmit issues, we clarified it
first. That way, it doesn’tpropagate; and you avoid hurting
the person involved.
LESSON LEARNED?
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SOUND WAVES AND THEIR SOURCES
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FOR YOUR ASSIGNMENT:
Do an advance reading on the speed of sound
in different media.Page 369 of your book.
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Thank you for listening!
Good day!
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