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Unit 6: Sound Page 10
Objectives
Lesson 2: Resonance
We’ve been talking about the · Sound is molecules moving back
fact that sound is caused by and forth (vibrating) creating
something vibrating. If you can longitudinal waves.
hear it, you can bet that
somewhere, something is vibrating · All sound comes from something
molecules and those molecules are vibrating.
vibrating your ear drums. The
sound may be coming from a car, · Frequency of sound waves
thunder, a balloon popping, determines the pitch.
clapping hands, or your gold fish · Sound waves with a high
blowing bubbles in her tank. frequency have high pitches.
However, no matter where it’s
coming from, what you are hearing Sound waves with low
is vibrating particles, usually frequencies have low pitches.
vibrating air molecules. · The human ear can hear sound
energy as low as 20 Hz and as
This lesson, I’d like to take the
high as 20,000 Hz.
concepts of frequency and
vibration just a bit further and talk · The more energy sound has, the
about natural frequency and
larger the wave is (higher
resonance.
amplitude) and the louder it is.
Highlights: · We hear sound because
vibrating particles vibrate our
· Sound is a type of energy and
eardrums and our brain
moves by longitudinal waves.
translates those vibrations into
· Sound moves faster in solid sound.
objects than it does in air
· Everything has a natural
because the molecules are very
frequency.
close together in a solid and
very far apart in a gas. · The natural frequency of an
object is due to the size, weight,
· Sound travels at about 760 mph
and material the object is made
in air, about 1000 ft/s. Sound
of.
can travel a mile in 5 seconds.
· Natural frequency is how fast
· Light travels much faster than
something vibrates.
sound.
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