Science Starter 12/11Think 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.

Sound VibrationIs a wave that vibrates

particles of matter A rapid back and forth movement

WHAT IS SOUND?!?!?

Decibels (dB) = measure of

intensity

Dispersion is the spreading out of energyExamples: 10 dB breathing20 dB whisper60 dB people talking80 dB vacuum cleaner100 dB power saw140 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.

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!

From 42sec to 2:58http://www.youtube.com/watch?v=wYeauSxXSBA&feature=related

How Do Our Ears Hear Sound Waves?

Vibrations travel though the ear canalThen the sound waves vibrate the eardrum, which moves the 3 bones in the ear called hammer, anvil, and stirrup

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.

Do ear cup example

http://www.youtube.com/watch?v=tkPj4IGbmQQ&feature=related

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/sIn Water-(Liquid) 1,400 m/sIn Steel-(Solid) 5,000 m/s

Speed of Sound in Different TemperaturesIf 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 12/12What 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!)

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?

Who was paying attention!

*Don’t Worry you can use your notes : D

Review Practice QuestionsQuestion 1-Which do you hear 1st . . . .1- Your postman saying “Hi” from 20ft away2- A car crash 500 meters away3- An air plane taking off 10,000 meters away

Review Practice QuestionsQuestion 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 once2-Sound is a wave3-Light travels faster than sound 4-That is just how much time the sound takes to reach the

listener

Review Practice QuestionsQuestion 3-How does cupping your hand to your ear help you hear?1-Sound waves move through you hand2-The hand reflects more sound waves into the ear3- More sound waves are refracted into the ear4-There is more air for the sound waves to move

through

Review Practice QuestionsQuestion 4-What effects the intensity of the sound most? Pick 21-Temperature of medium2-Length of medium3- Material of medium 4-Color of medium5-Transparcy of the medium

Review Practice QuestionsQuestion 5-Fill in the blanks: ________________ determines the pitch

and ____________________ determines the volume/loudness.

1-Wavelength:Intensity2-Frequency:Wavelength3-Intensity:Frequency4-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?