Science Starter 12/11
Think about the lab yesterday and write . . .
A Summary-What did do and What were your
results?
Claim- A statement you can prove that you learned
using your data.
Evidence- That will support your claim.
Science Knowledge-Your knowledge of how it
works; why did this happen.
WHAT IS SOUND?!?!?
Sound
Is a wave that vibrates
particles of matter
Vibration
A rapid back and forth
movement
Decibels (dB) = measure of intensity
Dispersion is the spreading out of energy
Examples:
10 dB breathing
20 dB whisper
60 dB people talking
80 dB vacuum cleaner
100 dB power saw
140 dB Firecrackers
IS THERE SOUND IN
SPACE?
Space is a vacuum, which means empty
space or very few particles.
Vibrations have to travel through matter in
order to make a sound.
In space there is no ‘air’ or medium for
the wave to vibrate, thus no sound can be
produced.
http://www.youtube.com/watch?v=wYeauSxXSBA&feature=related
From 42sec to 2:58
How do we produce sound?
We use our muscles in our body
to push air up from our lungs
into an narrow passage and through
the vocal cords, which are actually
folds!
The force of air causes them to vibrate
That action produces sound waves!
How Do Our Ears Hear
Sound Waves?
Vibrations travel though the
ear canal
Then the sound waves vibrate
the eardrum, which moves
the 3 bones in the ear called
hammer, anvil, and stirrup
Do ear cup example
http://www.youtube.com/watch?v=tkPj4IG
bmQQ&feature=related
Continued- How Do Our Ears Hear
Sound Waves?
The eardrum vibrating causes the
three bones in the ear to vibrate,
which is detected by the cochlea.
The cochlea has millions of little
hairs called cilia inside the ear fluid
that move with the vibrations.
The movement of the cilia against
the auditory nerve sends messages
for the brain to decipher.
What Affects the Speed of
Sound?
Temperature and medium effects the speed of
sound.
Speed of Sound in
Different Mediums
If the temperature for all three
examples is 20 degrees Celsius:
In Air- (Gas) sound waves travel at 344
m/s
In Water-(Liquid) 1,400 m/s
In Steel-(Solid) 5,000 m/s
Speed of Sound in
Different Temperatures
If you are in the desert and in it 115 degrees F sound will
travel faster, then if you are in the arctic and it is -20
degrees F!
Why?
At higher temperatures particles move faster. So if sound
waves push against the already fast moving particles, then
it will quickly pass through and vibrate the already fast
moving particles.
Science Starter 12/12
What Affects the Speed of Sound?
Would sound travel faster in cold air or hot air if
the humidity was the same? Why?
Would sound travel faster through water or
bricks? Why?
Waves Have Common
Features:
Frequency
A given number of waves in specific amount of
time, which determines the pitch.
The pitch is a characteristic of high and low
sounds.
Frequency is measured in hertz. (hz)
FREQUENCY
Higher frequency =
more waves per period
of time.
The Doppler
Effect
The Doppler Effect is a change in the perceived
pitch when the source of the noise is moving.
So to Further Explain: All waves, light and sound,
travel out from the source, but when the source
is moving towards you the waves get bunched
closed together making a higher frequency/pitch
and the waves trailing behind become spread
out making a lower pitch/frequency.
http://www.youtube.com/watch?v=Kg9F5pN5tlI
Amplitude
Amplitude determines intensity, which is just
how loud sound is.
Intensity or amplitude of sound is measured in
decibels (dB).
Longitudinal versus
Transverse
What kind of waves can we produce with a slinky?
We can produce both transverse and longitudinal
waves. In the picture below, (a) is a longitudinal wave
(compressional) , while (b) is a transverse wave.
Seismic Waves (Caused
by vibrations inside earth)
ECHO! (Sound Waves
Reflect off of Surfaces!)
Who was paying attention!
*Don’t Worry you can use your notes : D
1. What is sound?
2. What are the three, tiny bones that are in your ear?
3. What part of the ear has millions of hairs and fluid in it?
4. Explain the process that takes place in your ear when you
hear a sound.
5. Is it easier for sound waves to pass through a solid or a
liquid? Why?
6. Is it easier for sound waves to pass through a hot gas or a
cool gas? Why?
7. Frequency determines the __________ of the sound and is
measured in ______________.
8. Explain the Doppler Effect.
9. What is an echo?
Review Practice Questions
Question 1Which do you hear 1st . . . .
1- Your postman saying “Hi” from 20ft away
2- A car crash 500 meters away
3- An air plane taking off 10,000 meters away
Review Practice Questions
Question 2-
Why can you see something happen then hear it? For example a
tree far off falls then a second later you hear it.
1-The sound travels in many directions at once
2-Sound is a wave
3-Light travels faster than sound
4-That is just how much time the sound takes to reach the
listener
Review Practice Questions
Question 3-
How does cupping your hand to your ear help you hear?
1-Sound waves move through you hand
2-The hand reflects more sound waves into the ear
3- More sound waves are refracted into the ear
4-There is more air for the sound waves to move through
Review Practice Questions
Question 4-
What effects the intensity of the sound most? Pick 2
1-Temperature of medium
2-Length of medium
3- Material of medium
4-Color of medium
5-Transparcy of the medium
Review Practice Questions
Question 5-
Fill in the blanks: ________________ determines the pitch and
____________________ determines the volume/loudness.
1-Wavelength:Intensity
2-Frequency:Wavelength
3-Intensity:Frequency
4-Frequency: Intensity
What Do You Think?
If a tree falls in the
forest, and no
people or animals
are around to hear
it, does it make a
sound? WHY?