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Mechanical Waves

Mechanical Waves. Waves. Waves are wiggles in time and/or space Traveling disturbances that carry energy Waves are periodic and repeat themselves. Wave Definitions. Amplitude – (1/2) distance between lowest and highest point Wavelength is the distance between peaks. Wave Definitions.

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Mechanical Waves

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  1. Mechanical Waves

  2. Waves • Waves are wiggles in time and/or space • Traveling disturbances that carry energy • Waves are periodic and repeat themselves

  3. Wave Definitions • Amplitude – (1/2) distance between lowest and highest point • Wavelength is the distance between peaks

  4. Wave Definitions • Period is the time it takes to repeat itself • Frequency is the number of complete cycles in one second • Waves are expressed as sin graphs

  5. Example Which is correctly labeled?

  6. Example One wavelength is from ____ to ____?

  7. Example Which of these is not a periodic wave?

  8. Frequency • The number of complete cycles per second • Can be calculated using: f = 1 / T

  9. Transverse Waves • The oscillation is perpendicular to the direction of the waves motion • Wave oscillates up and down as it moves left to right

  10. Longitudinal Waves • Oscillate in the same direction same the motion of the wave • Follow one particle and follow it as it moves left to right

  11. Compression or Longitudinal Waves • Crests and Troughs analogous to

  12. Water Waves • Follow one particle is it transverse or longitudinal?

  13. Example Name the parts of the wave

  14. Example What direction do the particles oscillate?

  15. Vibrations • Caused by various means • A back and forth motion • Everything naturally vibrates

  16. Wave Interference • Occurs when two waves make contact with one another • Waves overlap and look much different then the original • Effect is additive

  17. Constructive Interference • When peaks overlap with peaks and troughs overlap with troughs • Constructive Interference

  18. Destructive Interference • When peaks overlap with trough and vice versa • Destructive Interference

  19. Example When these two waves meet at point P what will the resultant amplitude be?

  20. Example What is the amplitude when the waves meet?

  21. Wave Velocity • The velocity of a wave is directly proportional to its frequency and wavelength v = λf

  22. Example If this wave has a frequency of 40 Hz then what is the velocity of the wave?

  23. Examples • Determine the velocity of an ocean wave if it has a frequency of 3 Hz and a wavelength of 5 meters • Determine the frequency of a wave moving at 15 m/s and a wavelength of 3 meters

  24. Standing Waves • Waves produced by mechanical means that are in a confined space • Fundamental Harmonic • Second Harmonic • Third Harmonic

  25. Resonance Forced vibrations that match the natural frequency of vibration

  26. Harmonics Integral Wave patterns that result from a fixed wave vibrating

  27. Harmonics Formulas Standing wave on string Frequency = harmonic number X (v/2L) Open at both ends pipe Frequency = harmonic number X (v/2L) Open at one end pipe Frequency = harmonic number X (v/4L)

  28. Example A wave moves along a string at 10 m/s. Determine the frequency of the 5th harmonic if the string is 5 m long. Determine the harmonic of 680 Hz if a sound wave (340 m/s) moves in an open pipe that is 1 m long

  29. Beats • Are caused by the interference of two sound waves with slightly different frequencies • A beat is a point of maximum intensity or constructive interference

  30. Doppler Effect Equation

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