Mechanical Waves

2,372 views

Published on

Published in: Technology, Business

Mechanical Waves

  1. 1. Waves & the EM Spectrum
  2. 2. <ul><li>A. Wave – a transfer of energy </li></ul>
  3. 4. <ul><li>a. In a wave, molecules pass energy on to neighboring molecules </li></ul>
  4. 6. <ul><li>b. Waves don’t transport matter </li></ul>
  5. 7. <ul><li>c. All waves are produced by something that vibrates </li></ul>
  6. 8. <ul><li>d. A material through which a wave travels is a medium . </li></ul><ul><li>i. It can be solid, liquid, or gas . </li></ul>
  7. 9. <ul><li>Not all waves need a medium through which to travel. </li></ul><ul><li>ii. What is an example of this </li></ul><ul><li>type of wave? </li></ul>
  8. 11. <ul><li>B. Mechanical waves need a medium to travel. </li></ul><ul><li>They cannot travel through empty space. </li></ul>
  9. 12. <ul><li>Do sound waves travel faster through gases or liquids? </li></ul>
  10. 15. Sound Waves through Gas
  11. 16. <ul><li>Try this: Smack your hand down on your desk. It’s pretty loud, huh? </li></ul><ul><li>Now, lay your head down on your desk and smack again. Any louder? WHY? </li></ul>
  12. 17. <ul><li>Greek Theatre Design </li></ul>
  13. 18. <ul><li>Mechanical waves can only travel through a medium. </li></ul>
  14. 19. <ul><li>a. Transverse wave – matter is displaced at right angles as energy is transferred </li></ul>
  15. 22. Example: Water waves
  16. 24. <ul><li>b. Longitudinal Wave – </li></ul><ul><li>Matter is displaced in the same direction as the energy is transferred </li></ul>
  17. 27. Example: Sound Waves
  18. 28. <ul><li>a. They carry different amounts of energy </li></ul>
  19. 29. <ul><li>b. They travel at different speeds </li></ul>
  20. 31. Doppler Effect
  21. 33. MythBusters
  22. 34. <ul><li>i. Transverse - </li></ul>
  23. 35. <ul><li>ii. Longitudinal - </li></ul>
  24. 36. <ul><li>B. Wavelength – distance between a point on a wave and the nearest point just like it </li></ul><ul><li>SI Unit: m </li></ul>
  25. 37. <ul><li>C. Frequency – Number of wavelengths that pass a fixed point in one second </li></ul><ul><li>SI Unit: Hz </li></ul>
  26. 38. <ul><li>b. As frequency increases, wavelength decreases. </li></ul>
  27. 39. <ul><li>D. Wave Velocity – how fast the wave travels </li></ul><ul><li>a. Velocity = wavelength x frequency </li></ul><ul><li>SI Unit: m/s </li></ul>
  28. 40. <ul><li>b. Light vs. Sound </li></ul>
  29. 41. <ul><li>c. Sound waves travel faster in: </li></ul>
  30. 42. <ul><li>d. Light waves travel faster in: </li></ul>
  31. 43. <ul><li>E. Amplitude – </li></ul><ul><li>measure of energy in a wave </li></ul>
  32. 44. <ul><li>vs. </li></ul>a. The more energy a wave carries, the greater the amplitude.
  33. 45. <ul><li>b. Amplitude of transverse wave: </li></ul>
  34. 46. <ul><li>c. Amplitude of longitudinal waves: </li></ul>
  35. 47. <ul><li>A. Reflection occurs when </li></ul><ul><li>a wave strikes an object and </li></ul><ul><li>bounces off of it. </li></ul>
  36. 48. <ul><li>a. All types of waves can be reflected </li></ul>
  37. 50. <ul><li>b. </li></ul>
  38. 57. <ul><li>And now, </li></ul><ul><li>a word from our sponsors. . . </li></ul>
  39. 58. <ul><li>B Refraction is the bending of a wave </li></ul><ul><li>caused by a change in its speed. </li></ul>
  40. 63. <ul><li>a. The greater the change in speed is, the more the wave bends. </li></ul>Wave Refraction
  41. 64. <ul><li>C. Diffraction is when an object causes </li></ul><ul><li>a wave to change direction </li></ul><ul><li>and bend around it. </li></ul>
  42. 66. Diffraction
  43. 67. <ul><li>D. Interference – </li></ul><ul><li>the ability of two or more waves to combine and form a new wave </li></ul>
  44. 68. <ul><li>a. Waves add together </li></ul>
  45. 69. <ul><li>b. Waves subtract from each other </li></ul>
  46. 71. <ul><li>E. Resonance – the ability of any object to vibrate by absorbing energy at its natural frequency </li></ul>
  47. 72. Wine Glass Resonance
  48. 73. The End
  49. 76. <ul><li>Helpful reminders for the test: </li></ul><ul><li>Differences b/w experimental variables (Ind, Dep, Constant, Control) </li></ul><ul><li>Understand velocity & acceleration </li></ul><ul><li>Newton’s 3 Laws of Motion </li></ul><ul><li>Plotting Ind. & Dep. Variables </li></ul><ul><li>Energy </li></ul>

×