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Calculate the speed of 25 cm ripples passing through water at 120 waves/s

Calculate the speed of 25 cm ripples passing through water at 120 waves/s. Determine the l , f, & T of the 49 th overtone of a 4.0 m organ pipe when v sound = 350.0 m/s. Chapter 15. Sound. Sound Waves.

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Calculate the speed of 25 cm ripples passing through water at 120 waves/s

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  1. Calculate the speed of 25 cm ripples passing through water at 120 waves/s

  2. Determine the l, f, & T of the 49th overtone of a 4.0 m organ pipe when vsound = 350.0 m/s

  3. Chapter 15 Sound

  4. Sound Waves Longitudinal waves caused by pressure change producing compressions & rarefactions of particles in the medium

  5. Sound Waves Any vibrations produce regular oscillations pressure as the vibrating substance pushes air molecules back & forth

  6. Sound Waves The oscillating air molecule collide with others transmitting the pressure variations away from the source

  7. Sound Waves Air resistance will cause the amplitude of the wave to diminish as it moves away from the source

  8. Speed of Sound vsound in air = 331.5 m/s + (0.60 m/soC)(T)

  9. Speed of Sound vsound ~ 343 m/s At room temp.

  10. Speed of Sound at 25oC vin air = 343 m/s vfresh water = 1493 m/s vsea water = 1533 m/s vin steel = 5130 m/s

  11. The human ear can detect sound between 20 Hz & 16 kHz. Calculate the wavelength of each:

  12. Calculate the l in mm of notes with frequencies of: 2.0 kHz & 10.0 kHz vsound = 342 m/s

  13. Loudness • How loud sound is, is proportional to the amplitude of its waves

  14. Decibels (dB) • Unit for measuring the loudness of a sound wave

  15. Decibels • Measured in log units • 50 dB is 10 x greater than 40 dB

  16. Pitch • Pitch is proportional to the frequency or inversely proportioned to the wavelength

  17. Doppler Effect • Changes in observed pitch due to relative motion between the source & the observer of the sound wave

  18. Doppler Effect • The pitch of approaching objects has higher frequencies or shorter wavelengths

  19. Doppler Effect • The pitch of objects moving apart has lower frequencies or longer wavelengths

  20. The Physics of Music

  21. Almost all musical instruments are some form of an open tube or strings attached at two ends

  22. In brass instruments, the lip vibrates against the mouthpiece causing the instrument to vibrate

  23. In reed instruments, air moving over the reed causes it to vibrate causing the instrument to vibrate

  24. In pipe instruments, air moving over the opening causes air to vibrate causing the instrument to vibrate

  25. In stringed instruments, plucking the string causes it to vibrate causing the instrument to vibrate

  26. In musical instruments, the sound is dependent upon resonance in air columns

  27. In each instrument, the longest wavelength produced is twice the length of string or air column

  28. Resonance • When multiple objects vibrate at the same frequency or wavelength

  29. Resonance • Resonance increases amplitude or loudness as multiple sources reinforce the waves

  30. Resonance • The length & width of the air column determine the pitch (frequency or wavelength)

  31. Resonance • In instruments sound resonates at a fundamental pitch and many overtones

  32. Calculate the wavelengths for each of the following sound frequencies at 30.83oC:4.0 MHz & 10.0 MHz

  33. Fundamental • The lowest tone or frequency that can be generated by an instrument

  34. Overtones • Sound waves of higher frequency or pitch than the fundamental

  35. Pipe Resonance • Open Pipe: open at both ends • Closed Pipe: Closed at one end

  36. Pipe: Open End • High Pressure-antinode • Zero Displacement-node

  37. Pipe: Closed End • Pressure node • Displacement antinode

  38. Closed Pipe Resonator • A pipe that is closed at one end

  39. Open Pipe Resonator • A pipe that is open at both ends

  40. Wavelengths Generated by a Closed Pipe Resonator • = 4L/(2n +1) f = v(2n+1)/4L

  41. Wavelengths Generated by a Closed Pipe Resonator n = 0 for the fundamental

  42. Wavelengths Generated by a Closed Pipe Resonator n = positive integers for overtones

  43. Typical Wavelengths Generated by CP • 0 = 4L • 1 = 4L/3 • 2 = 4L/5

  44. Wavelengths Generated by an Open Pipe Resonator • = 2L/(n+1) f = (n+1)v/2L

  45. Wavelengths Generated by an Open Pipe Resonator n = 0 for the fundamental

  46. Wavelengths Generated by an Open Pipe Resonator n = positive integers for overtones

  47. Typical Wavelengths Generated by OP • 0 = 2L • 1 = 2L/2 • 2 = 2L/3

  48. Calculate the longest wavelength & the first two overtones produced using a 68.6 cm saxophone. (open)

  49. Calculate the wavelengths & frequencies of the longest & the first 4 overtones produced using a 2.0 m tuba.

  50. Calculate the wavelengths & frequencies of the lowest & the first 4 overtones produced using a 5.0 cm whistle. (closed)

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