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Warm-Up: March 27th

Delve into the world of sound waves, exploring their types, properties, and practical applications. Learn about longitudinal waves, frequency, pitch, and the Doppler Effect. Discover how sound waves carry energy and interact with mediums.

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Warm-Up: March 27th

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  1. Warm-Up: March 27th • What are the two types of mechanical waves? • Sound is what kind of wave? • What is the topmost part of a transverse wave called? • What makes up the wavelength of a longitudinal wave (what two parts)? • If you can see the light coming from another room (not directly), the lightwaves are bending. What do we call that?

  2. Sound Waves • Longitudinal – • Disturbance of medium is parallel to wave movement • MUST have a medium to travel in

  3. V  f Wave Speed • Velocity of a wave is calculated by multiplying wavelength by frequency • Vw=  x f *As f increases,  decreases!

  4. Example Problem 1: • A wave is generated in a wave pool at an amusement park. The wavelength is 3.2 m and the frequency is 0.60 Hz. What is the velocity of the wave? • V = x f 1.92 m/s

  5. Example Problem 2: • Earthquakes can produce three types of waves. One of these is a transverse wave called an “s” wave. A typical s wave travels at 5000 m/s. Its wavelength is 417 m. What is its frequency? • F = 12 Hz

  6. Example Problem 3: • A sound wave has a frequency of 500.0 Hz and a wavelength of 3.0 m. What is the speed of the wave? • V = x f

  7. Example Problem 4 • The lowest-pitched sounds humans can hear have a frequency of 20.0 Hz. What is the wavelength of these sound waves if their wave speed is 340.0 m/s? • V = x f

  8. Warmup March 28th Happy Spring Break!! • What kind of waves are sound waves? • Longitudinal • Electrical • Transverse • Both A and B

  9. 2. As frequency of a wave Increases, the length of a wave ___________(if velocity is same) • Increases • Stays the Same • Decreases

  10. 3. Sound travels fastest through • Solid • Liquid • Gas

  11. 4. Frequency of a wave determines a sound’s • Amplitude • Pitch • Intensity

  12. 5. What is the Frequency of a sound wave traveling 330m/s (in the air) with a wavelength of .55 meters? • 1550 Hz • 800 Hz • 775 Hz • 600 Hz

  13. ANSWERS TO WARMUP 1.A 2.C 3.A 4.B 5.D

  14. Frequency and Pitch • Pitch: The highness or lowness of sound • Depends on the frequency • High frequency = high pitch • Low frequency = low pitch • 20,000 Hz: ultrasonic waves • 20 Hz and below: infrasonic waves

  15. Intensity and Loudness • Loudness: Human perception of sound intensity. • Depends on the amplitude • Decibel Scale (dB) - Measures intensity of sound

  16. Waves go through mediums, and different mediums are transparent to different types of wave energy. But also, a wave’s energy can be partly or completely absorbed by the different medium When Waves Hit Things

  17. Sound – as Waves • Amplitude = volume • Frequency = pitch. High frequency, high pitch. Low frequency, low pitch. • Must have a medium – no medium, no sound. • Sound waves – What type of medium do they travel fastest through (solid, liquid, gas)?

  18. Measuring Sound • Decibel – a measure of the Sound Pressure Level. The higher the decibel, the more intense the sound.

  19. It happened to my uncle…he was one of the first people I ever knew to own a “SONY WALKMAN”He listened at very high volumes pretty much all day…now he is pretty much deaf……and it’s very much annoying for us and him!

  20. DID YOU HEAR WHAT I SAID???DON’T LET THIS HAPPEN TO YOU!!!!!!!!

  21. August 27, 1883 • Krakatoa • 180 dB • Loudest sound ever heard. • The sound itself caused tsunamis

  22. The Doppler EffectThe What?????Where have you heard the term “doppler” before? • http://www.youtube.com/watch?v=h4OnBYrbCjY&authuser=0 • http://www.youtube.com/watch?v=Djz_rtnXSfY&authuser=0

  23. The Doppler Effect • A change in the observed frequency of a wave when the source and observer (you) are in motion relative to each other. • The frequency appears to increase as the source get closer, and appears to decrease as it moves away.

  24. Cool sound stuff… • Supersonic (faster than the speed of sound) • Subsonic (slower than the speed of sound) • Sonic boom (what happens when you pass the speed of sound) • Infrasound (below 20 Hz)

  25. Sound Waves Carry Energy!! • https://www.youtube.com/watch?v=BE827gwnnk4

  26. Calculate the Wavelength of 3 different tuning forks Vw=  x f Speed of sound in air is 330m/s The frequency of each fork is printed on the stem Calculate the wavelength of three different tuning forks. 256, 312, 680

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