1. MECHANICAL WAVES

2. PHYSICS OLYMPICS

3. http://www.gravitykills.net/PhysicsOlympics/PhysicsOlympics.htm

4. 1. Safety! 2. Care & use of slinkys. SLINKY PRE-LAB:

5. Wave Definition: What’s the function of a wave?

6. Types of Waves

7. #1. ELECTROMAGNETIC - NO medium required - travel @ speed of light ex: light, radio waves, xrays, etc

8. #2. MECHANICAL How are these waves produced? What is the relationship between direction of propagation and displacement of the medium?

9. #2. MECHANICAL * requires a MEDIUM (solid, liq,gas) ex: water, sound, spring, etc.

10. “ TRANSVERSE ” ( solids ) disturbance is perpendicular to the direction wave travels TYPES of MECHANICAL DISTURBANCEDISTURBANCE MOTION

11. 1. “ TRANSVERSE ” ( solids ) particles vibrate at right angles to direction wave moves 4 Type MECHANICAL Waves

12. 2. “ LONGITUDINAL” (solid,liquid,gas) disturbance is parallel to direction wave moves 4 Types of MECHANICAL Waves DISTURBANCE MOTION

13. “ LONGITUDINAL ” (solid,liquid,gas) “ push or pull” 4 Types of MECHANICAL Waves

15. PULSE – a single disturbance that travels through a medium How is a pulse different than a wave ???

16. CREST – the high point of each wave TROUGH – the low point of each wave PERIOD – shortest time interval during which motion repeats itself

17. AMPLITUDE – the point of maximum displacement from rest or equilibruim How does amplitude affect wave speed?

18. trough crest amplitudeamplitude a m p li t u d e crest wavelength

19. WAVE SPEED What affects the rate at which a wave travels ????

20. v = f = wavelength = wavelength

21. WAVE LENGTH How does wavelength affect the wave speed????

22. FREQUENCY How does frequency affect the wave speed????

23. MEDIUM (media) How does medium affect the wave speed????

25. EXAMPLE #1 What is the period & frequency of the three hands of the clock?

26. EXAMPLE #2 A wave traveling in the x-direction with a frequency of 25 Hz is shown above. Find amplitude, wavelength, period & wave speed for this wave.

27. A sound wave traveling at 343 m/s is emitted by the foghorn of a tugboat. An echo is heard 2.60 s later. How far away is the reflecting object? EXAMPLE #3

28. A student drops a rock down a deep mineshaft. How deep is the mineshaft if he hears the rock hit the bottom 6.5 s after dropping it from rest? EXAMPLE #4

29. WAVE GRILLPRE-LAB:WAVE GRILLPRE-LAB: 1. Safety! 2. Care & use of wave grills.

31. Law of Superposition waves pass through each other unchanged amplitudes may be added/subtracted result is called...

32. A CONSTRUCTIVE interference waves ADD amplitudes when they meet displacements are on SAME sides point of maximum displacement “ANTINODE” (add) a b a + b

33. CONSTRUCTIVE interference  waves then pass through each other unchanged Website simulation click here

34. displacements are on opposite sides waves SUBTRACT amplitudes when they meet point of no disturbance is “NODE” DESTRUCTIVE interference N a b a - b a b

35. FIXED -END REFLECTION What happens to the medium at the boundary?

36. FREE -END REFLECTION What happens to the medium at the boundary?

37. SPEED OF SOUND PRE-LAB “ECHO” : “ECHO”

38. SPEED OF SOUND POST-LAB: “ECHO” 1. Explain the reflection of the pulses. 2. How is the speed of sound calculated? : 1 m

40. INTRO TO SOUND PRE-LAB :

41. THE SOUND OF MUSIC

42. longitudinal (parallel) velocity depends on medium, temp, elasticity, density, etc.

43. sound in air at 20 0 C = 344m/s (speed of light = 300,000,000m/s)

44. Waves travel slowest in gases

45. Pitch vs. frequency

46. Amplitude vs. Energy

47. Harmonics vs. Sound Quality

48. *Draw a longitudinal wave & identify areas of compression & rarefaction :

50. Resonance (Demonstrate with resonance boxes or speakers) –prolonging a sound by reflection “fundamental frequency ”

51. Beat  2 waves with slightly different frequencies interfere (throbbing) (Demonstrate with resonance boxes or speakers)

52. Example #5: Four beats per second are heard when a 256 Hz tuning fork is sounded with a second fork. What are the possible frequencies of the second fork? :

53. SPEED OF SOUND PRE-LAB “RESONANCE” :

54. SPEED OF SOUND POST-LAB “RESONANCE” :

55. Example #6: An open vertical tube is filled with water & a tuning fork vibrates over its mouth. As the water level is lowered in the tube, resonance is heard when the water level has dropped 17cm and again after 49 cm of distance exist from the water to the top of the tube. What is the frequency of the tuning fork?

57. Define normal line Write the geometric relationship line

58. wave hits boundary & bounces out angle of incidence EQUALS angle of reflection * * * always measure from NORMAL line barrier angle of incidence

59. wave hits boundary & bounces out angle of incidence EQUALS angle of reflection * * * always measure from NORMAL line barrier angle of incidence angle of reflection

60. “checker- board” barrier normal angle of reflection angle of incidence

61. Describe what happens to each of the following properties: –Wave speed –Wavelength –Frequency

62. bending of a wave due to a change in medium (ex: air to H 2 0) deep shallowshallow

63. Wave changes direction && speed at the boundary deep shallowshallow

64. shallowshallow Ex: deep to shallow  wavelength & vel. decr, but frequency stays the same!

65. How does the slit opening and frequency affect the wave pattern?

66. bending of waves around the edge of a barrier forms circular waves that spread smaller  = smaller diffraction

67. How does the source separation & frequency affect the wave pattern? INTERFERENCE

68. What effect does motion have on wave speed, wavelength & frequency? DOPPLER EFFECT

69. change in due to change in position of source