Essential Question (pg. 81): What
happens if the medium vibrates the
same way as the wave motion?
 It creates a longitudinal wave.
Which direction does the medium
vibrate in relation to the wave
motion for a longitudinal wave?
•
It vibrates parallel to the wave motion.
Can a longitudinal wave travel in
outer space?
•
No, longitudinal wave is a
mechanical wave, meaning that it
must travel through a medium and
since there are no air particles in
space, therefore, longitudinal
waves cannot exist.
Your Question: What are compressions?
•
Places where particles of a medium
crowd closer together.
Essential Question (pg. 85): How
are sounds made?
•
They are vibrations in the form of
wave energy.
What must happen for us to hear a sound?
•
When an object vibrates it compresses
surrounding air molecules and makes
them vibrate. (each molecule makes
the one next to it vibrate)
Can sound exist in space?
•
No, Because there are no particles in in
space to vibrate. Therefore, There is no
medium in space.
What is the difference between the pitch
and the loudness of sound?
•
Pitch: depends on frequency, meaning
how many waves are created in a given
amount of time.
•
Loudness: depends on amplitude, which
is the intensity of the energy transferred.
What is the SI unit for:
Pitch: Hertz (Hz)
Volume: Decibels (dB)
Why does sound travel faster in solids
than liquids:
•
Sound travels faster in solids than liquids,
because in solids the particles are closer
to each other, therefore, they can easily
pass the energy of vibration to nearby
particles.
Essential Question (pg. 91): Why do cars sound
different when they drive past me?
The perceived change in pitch and volume of
a moving car passing a stationary person is
due the Doppler Effect.
How will the sound of a train whistle change if
the train is moving away from me?
The sound of the train will be heard as a lower
pitch and volume, because as the train moves
away from a stationary person, the waves
spread out behind the train.
What causes the Doppler Effect?
Doppler effect happens when:
1. The
source of sound is moving relative to
the stationary listeners.
2. The
source of sound is stationary relative
to the moving listeners.
Do the Frequency and the amplitude
of the sound source actually
change?
•
No, they seem to be changing
because the sound source is
moving relative to the listeners.
Essential Question (pg. 93): How does
science help us understand how
instruments work?
It helps us understand how “sound” is
created as a result of vibrating of objects.
What do all musical instruments have in
common?
1. They
all create sound by causing matter
to vibrate.
2. Most
instruments use resonance to
amplify sound.
3. Most
instruments have a way of
changing frequency of the sound.
What is resonance?
Resonance occurs when external vibrations match
an object’s natural vibration or when vibration of
one object causes another object to vibrate at the
same frequency.
Your Question: which part of the
wave does resonance increase?
Resonance increases amplitude of
vibration is increased.
Essential Question (pg. 97): How do scientists
and engineers use sound?
They use sound in different technologies such
as:
• sonar to locate objects like submarines
underwater.
• Ultrasonography to see inside the human
body.
How does a bat find its food at night?
Echolocation: It sends out ultrasound
waves and use their echo/reflection
in order to locate objects they
cannot see.
Explain how a fisherman's’ fish finder
works?
•
Uses a sonar system, which sends
and receives ultrasounds to locate
the fish.
What is the formula used to calculate
distance?
Distance = Speed x Frequency
Bill nye:
https://www.youtube.com/watch?v=j1Q5TFMqsFo
Longitudinal vs. Transverse:
https://www.youtube.com/watch?v=7cDAYFTXq3E
Frequency vs. volume
https://www.youtube.com/watch?v=YTZcSaPn92s
Breaking wine glass using resonance:
https://www.youtube.com/watch?v=IZD8ffPwXRo
Washing machine breaking due to resonance: (start from 15 seconds)
https://www.youtube.com/watch?v=vROdVsU_K80
How sonar works
https://www.youtube.com/watch?v=Hx0G2712QiA
Dolphins and bats
https://www.youtube.com/watch?v=Odq7W2u2Xj8
The Doppler Effect:
https://www.youtube.com/watch?v=h4OnBYrbCjY
Resonance causing destruction (Tacoma bridge destruction, 1940)
https://www.youtube.com/watch?v=nFzu6CNtqec
Wave
Medium
Frequency
Mechanical waves
Decibels
Pitch
Transverse waves
Electromagnetic waves
Longitudinal waves (compression waves)
Compression
rarefaction
Wavelength
Volume
Sound
amplitude
Hertz