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Do Now: 4/16

Do Now: 4/16. A radio wave broadcasts at 700 kHz and travels the speed of light (3x10 8 m/s). 1.What is the period? 2.What is the wavelength?. Properties of Sound. 4/6/11. Sound waves. Sound wave: a mechanical wave transmitted through matter (a material medium ). Sound Waves:.

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Do Now: 4/16

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  1. Do Now: 4/16 A radio wave broadcasts at 700 kHz and travels the speed of light (3x108m/s). 1.What is the period? 2.What is the wavelength?

  2. Properties of Sound 4/6/11

  3. Sound waves • Sound wave: a mechanical wave transmitted through matter (a material medium)

  4. Sound Waves: • Sound is a longitudinal wave:

  5. Pressure Variations • Compression: particles closer together • Rarefaction: particles farther apart

  6. Properties of Sound: Pitch • Pitch: The sensation of a frequency Higher pitch! 

  7. http://www.physicsclassroom.com/class/sound/U11l2a.cfm

  8. Music Consonant: Certain sound waves which, when played simultaneously, will produce a pleasant sound

  9. Example: Two musical notes that have a frequency ratio of 2:1 are said to be separated by an octave. A musical note that is separated by an octave from middle C (256 Hz) has a frequency of _____. a. 128 Hz b. 254 Hz c. 258 Hz d. 345 Hz e. none of these

  10. Review: Amplitude • Amplitude represents energy

  11. Properties of Sound: Loudness • Loudness depends on the amplitude of sound waves; measured in decibels (dB) • Intensity (I): how loud a sound is in relation to another

  12. Example: A mosquito's buzz is often rated with a decibel rating of 40 dB. Normal conversation is often rated at 60 dB. How many times more intense is normal conversation compared to a mosquito's buzz? a. 2 b. 20 c. 100 d. 200 e. 400

  13. Speed of Sound: The speed of sound depends primarily on medium but also on temperature: v = 331 m/s + (0.6 m/s/C)•T

  14. Example: Determine the speed of a sound wave in air at a temperature of 20ºC. v = 331 m/s + (0.6 m/s/C)•T v = 331 m/s + (0.6m/s/C)•(20 C) v = 331 m/s + 12 m/s v = 343 m/s

  15. Echo: • echo: a reflected sound; will take twice the time to travel the same distance • Example: a sound wave travels 500 m to a cliff, then returns to where it started. If the sound wave traveled 330 m/s, how long does it take the sound to return to where it started?

  16. Practice: • Use the rest of class to work on the worksheet “Sound Waves.” • Be prepared to answer an exit question at the end of class

  17. Exit Question: • Which property of sound is determined by amplitude? • Which property of sound is determined by frequency?

  18. Do Now (4/17/12): • Which property of sound is determined by amplitude? • Which property of sound is determined by frequency? • What is the velocity of sound when the temperature is 44˚ C?

  19. Agenda: • 4th Q Project • Homework questions • Extra credit (optional)

  20. Fourth quarter project • Deadline 1: TOMORROW Bring in your favorite piece of art, or any art piece that speaks to you. It can be a drawing, a painting, a sculpture, etc. You may make a photocopy, or print it from a computer, but you MUST have a hard copy with you… on your phone doesn’t count!!! You will also write a paragraph about your piece, but we will do that tomorrow.

  21. Practice: • Work on homework • Work on extra credit (optional) – if you want extra credit, the work must be submitted by the end of class • Begin thinking about your art piece – feel free to look through your history or English textbook once you have finished your work.

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