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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
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?

sound waves
Sound waves
  • Sound wave: a mechanical wave transmitted through matter (a material medium)
sound waves1
Sound Waves:
  • Sound is a longitudinal wave:
pressure variations
Pressure Variations
  • Compression: particles closer together
  • Rarefaction: particles farther apart
properties of sound pitch
Properties of Sound: Pitch
  • Pitch: The sensation of a frequency

Higher pitch! 

music
Music

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

example
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

review amplitude
Review: Amplitude
  • Amplitude represents energy
properties of sound loudness
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
example1
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

speed of sound
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

example2
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

slide16
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?
practice
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
exit question
Exit Question:
  • Which property of sound is determined by amplitude?
  • Which property of sound is determined by frequency?
do now 4 17 12
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?
agenda
Agenda:
  • 4th Q Project
  • Homework questions
  • Extra credit (optional)
fourth quarter project
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.

practice1
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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