2. Day 1 Pick up handouts on the front table!

3. What happens to the surface of a pond when a stone is tossed into the water? Explain why. Agenda Types of mechanical waves. Parts of a wave. Relationships among speed, wavelength, and frequency.

4. Q1: W HAT IS AN EXAMPLE OF A BIOTIC FACTOR ? A. dirt B. air C. grass D. water S.C.8.3.3.d DOK 1

5. Q2: W HY ARE HUMANS ABLE TO SEE WITH THEIR EYES ? SC8.2.3.d DOK 1 A. light enters the eye B. light is sent out of the eye C. light gets trapped in the eye D. light has nothing to do with sight

6. On a test, the 20 students that finished in less than 30 minutes had an average of 80. The average of the 10 boys students that finished in 30 minutes or more was 75. What was the overall average of the class?

7. Greek /LatinParagraph flex- tetra- calor- bi- phon-

8. I will know the three different types of mechanical waves. I will know the relationships among speed, wavelength, and frequency. I will be able to identify and name the different parts of a wave structure. I will be able to solve story problems for the wave equation.

9. What happens to the surface of a pond when a stone is tossed into the water? Answer: A ripple appears on the surface of the pond. Centering on where the surface was broken with the energy dispersing outward.

10. A1: W HAT IS AN EXAMPLE OF A BIOTIC FACTOR ? A. dirt Dirt is non-living which is abiotic. B. air Air is non-living which is abiotic. C. grass Grass is a living organism which is biotic. D. water Water is non-living which is abiotic. S.C.8.3.3.d DOK 1

11. A2: W HY ARE HUMANS ABLE TO SEE WITH THEIR EYES ? SC8.2.3.d DOK 1 A. light enters the eye Light entering the eye, the eye reacts to the light, signals are sent to the brain which tells you what you are seeing. B. light is sent out of the eye Eyes do not produce light. C. light gets trapped in the eye Light enters the eye, but does not get trapped. D. light has nothing to do with sight If light is not present, everything would appear black, in other words you would see nothing.

12. The 20 students that finished in less than 30 minutes had an average of 80. The average of the 10 students that finished in 30 minutes or more was 75. What was the overall average of the class? The score < 30 minutes = 20 × 80 = 1600 The score ≥ 30 minutes = 10 × 75 = 750 Total for the class = 1600 + 750 = 2350 Total Number of students = 20 + 10 = 30 Average of the class = 2350 ⁄ 30 = 78.3

13. In a wave pool, the waves carry energy across the pool. You can see the effects of a wave's energy when the wave lifts people in the water. Fun Fact:

14. A mechanical wave is a disturbance in matter that carries energy from one place to another. The material through which a wave travels is called a medium.

15. Solids, liquids, and gases all can act as mediums.

16. A vibration is a repeating back-and-forth motion.

17. The speed of a wave can change if it enters a new medium.

18. What causes mechanical waves? A mechanical wave is created when a source of energy causes a vibration to travel through a medium.

19. Three main types of mechanical waves: -- transverse waves -- longitudinal waves -- surface waves

20. 1. A transverse wave causes the medium to vibrate in a direction perpendicular to the direction in which the wave travels. Crest Direction of wave Trough Direction of vibration

21. E XAMPLE OF TRANSVERSE WAVES ! http://www.kettering.edu/~drussell/Demos/waves/wavemotion.html

22. The wave carries energy from left to right, in a direction perpendicular to the up-and-down motion of the rope. Transverse Waves

23. PARTS OF A WAVE The highest point of the wave is the crest. The lowest point of the wave is the trough.

24. Amplitude The amplitude of a wave is the maximum displacement of the medium from its rest position.

25. The more energy a wave has, the greater is its amplitude. Rest position High amplitude Low amplitude

26. Wavelength can be measured from any point on a wave to the same point on the next cycle of the wave. Long wavelengthShort wavelength Rest position

27. 2. A longitudinal wave is a wave in which the vibration of the medium is parallel to the direction the wave travels. Direction of wave Direction of vibration

28. A N EXAMPLE OF A LONGITUDINAL WAVE IS A SLINKY

29. P USH AT ONE END AND..

30. SUMMARY

31. A surface wave is a wave that travels along a surface separating two media. Example: Ocean waves

32. Turn to a partner #1 1. How does a mechanical wave carry energy from one place to another? A. vibration of a medium B. physical transfer of matter C. phase changes of a medium D. interaction of electromagnetic fields

33. Turn to a partner #1 -- answer 1. How does a mechanical wave carry energy from one place to another? A. vibration of a medium B. physical transfer of matter C. phase changes of a medium D. interaction of electromagnetic fields

34. Turn to a different partner #2 2. Name the wave in which the vibration of the medium is parallel to the direction the wave travels. A. longitudinal wave B. sound wave C. surface wave D. transverse wave

35. Turn to a different partner #2 2. Name the wave in which the vibration of the medium is parallel to the direction the wave travels. A. longitudinal wave B. sound wave C. surface wave D. transverse wave

36. Turn to a partner #3 3. Which example describes a transverse wave? A. sound wave traveling through air B. ocean wave far from the shore C. ocean wave as it approaches the shore D. light wave traveling through space

37. Turn to a partner #3 3. Which example describes a transverse wave? A. sound wave traveling through air B. ocean wave far from the shore C. ocean wave as it approaches the shore D. light wave traveling through space

38. S MALL GROUP : Discuss a sport where the athlete would need to understand the properties of waves.

39. ONE EXAMPLE: A surfer needs to understand the properties of waves.

40. Frequency is the number of complete cycles in a given time. Frequency is measured in cycles per second or hertz (Hz).

41. FUN FACT: Hertz is named after Heinrich Hertz (1857 to 1894) -- not the car company!

42. Turn to a partner: What determines the frequency of a wave?

43. Turn to a partner -- answer What determines the frequency of a wave? Answer: The number of complete cycles.

44. The time required for one cycle is called the time period. unit -- second

45. A. A wave vibrating at one cycle per second has a frequency of 1.0 Hz. B. A wave vibrating at two cycles per second has a frequency of 2.0 Hz. Second & Hertz – how they are connected Frequency = 1.0 hertz One cycle per second Frequency = 2.0 hertz Two cycles per second

46. Wavelength and Frequency Relationship If you assume that waves are traveling at a constant speed, then wavelength is inversely proportional to frequency. Increasing the frequency of a wave decreases its wavelength.

47. Wave Velocity Equation velocity = wavelength × frequency V = λ × f v f λ

48. Turn to a partner and write down the three equations using this triangle v f λ

49. Turn to a partner and write down the three equations using this triangle -- answer v f λ V = λ × f f = v ÷ λ λ = v ÷ f

50. When the velocity is constant – if the wavelength increases then the frequency will decrease. Relationships V = λ × f

51. Speed of Mechanical Waves One end of a rope vibrates to produce a wave with a wavelength of 0.25 meter. The frequency of the wave is 3.0 hertz. What is the speed of the wave? Hint: Hz = 1/s Modeled Practice

52. Speed of Mechanical Waves -- answer One end of a rope vibrates to produce a wave with a wavelength of 0.25 meter. The frequency of the wave is 3.0 hertz. What is the velocity of the wave? Hint: Hz = 1/s Givens: 0.25 m = λ 3.0 hertz = f Unknown: v Equation: V = λ × f Plug in numbers: v = (0.25 m)(3.0 Hz) (Units involved) (0.25 m)(3.0 1/s) Answer: 0.75 m/s

53. Turn to a partner: Is your answer reasonable?

54. Is your answer reasonable? -- answer Because the frequency is 3.0 hertz, the wave should travel a distance of 3 wavelengths in 1 second. This distance is 0.75 meters, which agrees with the calculated speed of 0.75 m/s.

55. What is the wavelength of an earthquake wave if it has a velocity of 5,000 m/s and a frequency of 10 Hz? Small Group:

56. Partner Practice – Answer What is the wavelength of an earthquake wave if it has a velocity of 5,000 m/s and a frequency of 10 Hz? Hint: Hz = 1/s Givens: 5,000 m/s = v 10.0 hertz = f Unknown: λ Equation: λ = v ÷ f Plug in numbers: λ = (5,000 m/s) ÷ (10 1/s) Answer: λ = 500 m

57. A wave on a rope has a wavelength of 2.0 m and a frequency of 2.0 Hz. What is the speed of the wave? Individual Practice

58. Individual Practice – Answer A wave on a rope has a wavelength of 2.0 m and a frequency of 2.0 Hz. What is the speed of the wave? Hint: Hz = 1/s Givens: 2.0 m = λ 2.0 hertz = f Unknown: v Equation: V = λ × f Plug in numbers: v = (2.0 m)(2.0 Hz) (Units involved) (2.0 m)(2.0 1/s) Answer: 4 m/s

59. Sound waves are longitudinal waves Sound Waves

60. In general, sound waves travel fastest in solids, slower in liquids, and slowest in gases. The speed of sound depends on many factors, including the density of the medium and temperature. Properties of Sound Waves

61. FUN FACT Ultrasound is used in a variety of applications, including sonar and ultrasound imaging. Most people hear sounds between 20 hertz and 20,000 hertz. Ultrasound is sound at frequencies higher than most people hear.

62. Small Group: Discuss when you would need an ultrasound.

63. Ultrasound can be used to make images of the heart to see how your heart beats. Small group: Discuss when you would need an ultrasound. -- answer

64. Sound energy is recorded by converting sound waves into electronic signals (electrical energy) that can be processed and stored. Sound is reproduced by converting electronic signals back into sound waves.

65. 1. Name the different parts of the given wave diagram. 2. How many waves are there in the diagram shown above?

66. 1. Name the different parts of the given wave diagram. Answer: 2. How many waves are there in the diagram shown above? Answer: one and a half wave = 3/2 λ

67. HOMEWORK – 1. R EAD PAGES 500 – 507 2. W AVE WORKSHEET #1