Science Starter 12/11

1. 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.

2. WHAT IS SOUND?!?!? Sound Vibration Is a wave that vibrates particles of matter A rapid back and forth movement

3. Decibels (dB) = measure of intensityDispersion 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

4. 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.

5. 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!

6. 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

7. Do ear cup example http://www.youtube.com/watch?v=tkPj4IGbmQQ&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.

8. What Affects the Speed of Sound? • Temperature and medium effects the speed of sound.

9. 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

10. 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.

11. 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?

12. Waves Have Common Features:

13. 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)

14. FREQUENCY • Higher frequency = more waves per period of time.

15. 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

16. Amplitude • Amplitude determines intensity, which is just how loud sound is. • Intensity or amplitude of sound is measured in decibels (dB).

17. 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.

18. Seismic Waves (Caused by vibrations inside earth)

19. ECHO! (Sound Waves Reflect off of Surfaces!)

20. Who was paying attention!*Don’t Worry you can use your notes : D • What is sound? • What are the three, tiny bones that are in your ear? • What part of the ear has millions of hairs and fluid in it? • Explain the process that takes place in your ear when you hear a sound. • Is it easier for sound waves to pass through a solid or a liquid? Why? • Is it easier for sound waves to pass through a hot gas or a cool gas? Why? • Frequency determines the __________ of the sound and is measured in ______________. • Explain the Doppler Effect. • What is an echo?

21. Review Practice Questions Question 1- Which 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

22. 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

23. 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

24. 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

25. 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

26. 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?