2. Physics 101: Lecture 22, Pg 1 Physics Sound Review Review and Assessment with Clickers! Chapeter test

3. Physics 101: Lecture 22, Pg 2 Speed of Sound l sound waves require a medium to travel l speed of those waves depends on the density and atomic forces (tension) in the medium: l Speed = square root(Force /density) l Speed in air is given by V= 331 + 0.6*Temp

4. Physics 101: Lecture 22, Pg 3 Speed of Sound l Rank these medium from fast to slow: a. Air > water > steel b. Steel > water > air c. Water >air > steel d. Trick question- all the same!

5. Physics 101: Lecture 22, Pg 4 Speed of Sound l Rank these from medium from fast to slow a. Air > water > steel b. Steel > water > air c. Water >air > steel d. Trick question- all the same! MediumSpeed (m/s) Steel5600 Water1500 Air344 Steel is 15x air Water is 3x air

6. Physics 101: Lecture 22, Pg 5 Speed of Sound speed in air is given by V= 330 + 0.6*Temp (where temp is always measured in celcius) What is the speed of sound in m/s at room temperature which is about 20 C? a. 340b. 550 c. 343d. 350

7. Physics 101: Lecture 22, Pg 6 Speed of Sound speed in air is given by V= 330 + 0.6*Temp (where temp is always measured in celcius) What is the speed of sound in m/s at room temperature which is about 20 C? a. 340b. 550 c. 343d. 350

8. Physics 101: Lecture 22, Pg 7 What is a Wave? l Movement (wiggle & jiggle) in Space & Time l Transfer Energy (Info) without transferring Mass l All waves have similar properties! l Sound vibrations move along with the wave and are called longitudinal waves l Light vibrations move perpendicular to the wave’s motion and are called transverse

9. Physics 101: Lecture 22, Pg 8 Transverse Waves The following video demonstrates the motion of a Transverse Wave…

10. Physics 101: Lecture 22, Pg 9 Longitudinal Waves The following video demonstrates the motion of a Longitudinal Wave…

11. Physics 101: Lecture 22, Pg 10 What type of wave is this? A. sound b. light c. water wave d. radio

12. Physics 101: Lecture 22, Pg 11 What type of wave is this? A. sound b. light c. water wave d. radio

13. Physics 101: Lecture 22, Pg 12 Which statement is totally true? a.. sound is a longitudinal wave that does not exist at ultra sound frequencies b. Sound is a transverse wave that exists at infrasonic and ultrasonic frequencies c. Sound is a longitudinal wave that does not exist in outer space d. Sound is a transverse wave that does not exist above 120 dB

14. Physics 101: Lecture 22, Pg 13 Which statement is totally true? a.. sound is a longitudinal wave that does not exist at ultra sound frequencies b. Sound is a transverse wave that exists at infrasonic and ultrasonic frequencies c. Sound is a longitudinal wave that does not exist in outer space d. Sound is a transverse wave that does not exist above 120 dB

15. Physics 101: Lecture 22, Pg 14 Wave parts (M=10 6,  =10 -6 ) Crests Troughs Amplitude (A) Wavelength (  Equilibrium  wave

16. Physics 101: Lecture 22, Pg 15 Wave Characteristics v =  f Wavelength (  : Distance it takes for Wave to repeat itself (units in meters) l Period (T): Time for one complete cycle (units in seconds) l Frequency (f): Number of complete cycles per unit time (units in 1/sec or Hz) Unit Analysis: m/s = (m)(1/s) f = 1/T F Wave Velocity (v): Speed of wave propagation (units in m/s)

17. Physics 101: Lecture 22, Pg 16 What is shown here? A. frequency b. wavelength c. period d. amplitude

18. Physics 101: Lecture 22, Pg 17 What is shown here? A. frequency b. wavelength c. period d. amplitude

19. Physics 101: Lecture 22, Pg 18 A 100 Hz wave contains 10 waves every 20 m. What is it’s speed? A. 1 m/sb. 2 m/s c. 5m/sd. 200 m/s v = d/t v=  f v = /T

20. Physics 101: Lecture 22, Pg 19 A 100 Hz wave contains 10 waves every 20 m. What is it’s speed? A. 1 m/sb. 2 m/s c. 5m/sd. 200 m/s v = d/t v=  f v = /T

21. Physics 101: Lecture 22, Pg 20 If you shake a slinky at twice the frequency… a. amplitude doubles b. period doubles c. speed doubles d. no answer

22. Physics 101: Lecture 22, Pg 21 If you shake a slinky at twice the frequency… a. amplitude doubles b. period doubles c. speed doubles d. no answer

23. Physics 101: Lecture 22, Pg 22 Physics of Music Beat is humming sound between 2 closely matched frequencies (beat frequency= f 2 – f 1 ) Octave = double or half frequency half step = frequency * 1.059 (1.059 * itself 12 times = 2 since 12 notes in an octave)

24. Physics 101: Lecture 22, Pg 23 Beats are due to interference l Consider two harmonic waves A and B meeting at x=0. A(  1 t) B(  2 t) CONSTRUCTIVE INTERFERENCE DESTRUCTIVE INTERFERENCE C(t) = A(t) + B(t)

25. Physics 101: Lecture 22, Pg 24 A4 is middle A on a piano with a 440Hz. What is the frequency of the next A note 12 keys higher? A. 441b. 880 C. 439d. 220

26. Physics 101: Lecture 22, Pg 25 Your guitar string should play 256 Hz, but when you play a 256Hz tuned piano key at the same time you hear a beat frequency of 2 hz. What is the frequency of your strings? A.2 b. 258 c. 254 or 258 d. 512

27. Physics 101: Lecture 22, Pg 26 Intensity and Loudness l Intensity is the power per unit area. (W/m 2 ) è I = P / A where P = power in watts A = area = 4*pi *d 2 (d=distance away) è Threshold for hearing I 0 = 10 -12 W/m 2 l Loudness (Decibels) is the perception of intensity  Measured on log scale using decibels    = (10 dB) log 10 ( I / I 0 )

28. Physics 101: Lecture 22, Pg 27 Bow Waves source of a wave moves faster than the sound waves Ex: Boat faster water waves V-Shaped pattern of bow waves behind the boat.

29. Physics 101: Lecture 22, Pg 28 Shock Waves A Shock Wave = 3-D version of 2-D Bow Wave. Except that the shock wave is shaped conically while the bow wave is a V-Shape.

30. Physics 101: Lecture 22, Pg 29 Sonic Boom Plane travels faster than sound Sound waves overlap– constructive interference sonic boom is continuously formed behind jet Mach number = speed plane / speed of sound Mach = jet distance/sound distance jet distance Sound distance

31. Physics 101: Lecture 22, Pg 30 Sonic Boom What is the mach number of this plane? 1. 12. 2 3. 3 4. 4

32. Physics 101: Lecture 22, Pg 31 Sonic Boom What is the mach number of this plane?

33. Physics 101: Lecture 22, Pg 32 Intensity and Loudness Rules of 10 dB 10 times more people is 10x more sound it’s 10 more dB it’s 10x more intense but it only sounds 2x louder to us Compare to 1 person whispering:0 dB, I o 10 people talking:10 dB, I = 10x, loudness = 2x 100 people talking:20 dB, I=100x, loudness=4x 1000 people talking: 30 dB, I=1000x, loudness=8x

34. Physics 101: Lecture 22, Pg 33 Intensity and Loudness Rules of 3 dB 2 times more people is 2x more intensity but it only sounds 1.7x louder to us Compare to 1 person whispering:0 dB, I o 2 people talking:3 dB, I = 2x, 4 people talking:6 dB, I= 4x, 8 people talking: 9dB, I= 8x 16 people talking:12 dB, I= 16x

35. Physics 101: Lecture 22, Pg 34 Intensity ACT l Recall Intensity = P/A. If you are standing 6 meters from a speaker, and you walk towards it until you are 3 meters away, by what factor has the intensity of the sound increased? 1) 22) 43) 8 4) 18

36. Physics 101: Lecture 22, Pg 35 Intensity ACT l Recall Intensity = P/A. If you are standing 6 meters from a speaker, and you walk towards it until you are 3 meters away, by what factor has the intensity of the sound increased? 1) 22) 43) 8 4) 18

37. Physics 101: Lecture 22, Pg 36 Decibels ACT l If 1 person can shout with loudness 50 dB. How loud will it be when 100 people shout? 1) 52 dB2) 70 dB3) 150 dB

38. Physics 101: Lecture 22, Pg 37 Intense Concert Physics Suppose at a concert you want to quadruple (4x) how loud it sounds. Since you can’t quadruple the number of speakers w/o permission, how much closer should you get to quadruple your listening pleasure? 1. 2x close2. 4x closer3. 8x closer4. 16x closer

39. Physics 101: Lecture 22, Pg 38 Intense Concert Physics Suppose at a concert you want to quadruple (4x) how loud it sounds. Since you can’t quadruple the number of speakers w/o permission, how much closer should you get to quadruple your listening pleasure? 1. 2x close2. 4x closer3. 8x closer4. 16x closer

40. Physics 101: Lecture 22, Pg 39 Intense Concert Physics Suppose at a concert you want to decrease how loud it sounds By 100 times using ear plugs. How many decibels is this? 1. 0dB2. 3 dB3. 6 dB4. 20 dB

41. Physics 101: Lecture 22, Pg 40 Intense Concert Physics Suppose at a concert you want to decrease how loud it sounds By 100 times using ear plugs. How many decibels is this? 1. 0dB2. 3 dB3. 10 dB4. 20 dB

42. Physics 101: Lecture 22, Pg 41 Constructive Interference Constructive Interference occurs when 2 waves combine with their troughs lining up, and their crests lining up. Once aligned, a wave “grows” between the waves, demonstrating increased size.

43. Physics 101: Lecture 22, Pg 42 Destructive Interference Diagram The following demonstrates Destructive Interference…

44. Physics 101: Lecture 22, Pg 43 Standing Waves are integer multiples of harmonics Node…. Node Strings, flutes  /2,, 3/2 /, … Anti-Node…. Node clarinet, palm pipe  /4, 3 , 5/4, …

45. Physics 101: Lecture 22, Pg 44 How many waves is this 1 st harmonic (fundamental)? A. ¼ b. ½ c. 3/2 d. 1

46. Physics 101: Lecture 22, Pg 45 How many waves is this 1 st harmonic (fundamental)? A. ¼ b. ½ c. 3/2 d. 1

47. Physics 101: Lecture 22, Pg 46 Which harmonic wave is this: a. 1 st b. 2 nd c. 3 rd d. 4th

48. Physics 101: Lecture 22, Pg 47 Which harmonic wave is this: a. 1 st b. 2 nd c. 3 rd d. 4th

49. Physics 101: Lecture 22, Pg 48 This 3 rd harmonic forms in a. guitarb. flute c. clarinet d. organ pipe

50. Physics 101: Lecture 22, Pg 49 This 3 rd harmonic forms in a. guitarb. flute c. clarinet d. organ pipe

51. Physics 101: Lecture 22, Pg 50 Resonance ACT l What happens to the fundamental frequency of a pipe, if the air (v=300 m/s) is replaced by helium (v=900 m/s)? 1) Increases2) Same3) Decreases

52. Physics 101: Lecture 22, Pg 51 Resonance ACT l What happens to the fundamental frequency of a pipe, if the air (v=300 m/s) is replaced by helium (v=900 m/s)? 1) Increases2) Same3) Decreases

53. Physics 101: Lecture 22, Pg 52 Organ Pipe A 0.9 m organ pipe (open at both ends) is measured to have it’s first harmonic at a frequency of 382 Hz. What is the wavelength of this note? a.1.8 m b. 0.9m c. 0.45m d. No idea and can’t draw pictures L=0.9 m

54. Physics 101: Lecture 22, Pg 53 Organ Pipe A 0.9 m organ pipe (open at both ends) is measured to have it’s first harmonic at a frequency of 382 Hz. What is the wavelength of this note? a.1.8 m b. 0.9m c. 0.45m d. No idea and can’t draw pictures L=0.9 m

55. Physics 101: Lecture 22, Pg 54 Organ Pipe A 0.9 m organ pipe (open at both ends) has a speed of sound of 180 m/s. What is it’s frequency? L=0.9 m A.1.8 b. 180 c.100 d. Idk, need wavelength

56. Physics 101: Lecture 22, Pg 55 Organ Pipe A 0.9 m organ pipe (open at both ends) has a speed of sound of 180 m/s. What is it’s frequency? L=0.9 m A.1.8 b. 180 c.100 d. Idk, need wavelength

57. Physics 101: Lecture 22, Pg 56 Doppler Effect l When source is moving toward you: è Distance between waves decreases è Frequency increases è Velocity of sound is still same (same medium) l When source is moving away from you: è Distance between waves increases è Frequency decreases è Velocity of sound is same (same air,same temp)

58. Physics 101: Lecture 22, Pg 57 Preflight 5 l As a police car passes you with its siren on, the frequency of the sound you hear from its siren 1) Increases2) Decreases3) Same Doppler Example Audio Doppler Example Visual

59. Physics 101: Lecture 22, Pg 58 Preflight 5 l As a police car passes you with its siren on, the frequency of the sound you hear from its siren 1) Increases2) Decreases3) Same Doppler Example Audio Doppler Example Visual

60. Physics 101: Lecture 22, Pg 59 Doppler ACT A: You are driving along the highway at 65 mph, and behind you a police car, also traveling at 65 mph, has its siren turned on. B: You have both pulled over to the side of the road, and a police car turns on a siren and travels past you as they chase after someone else In which case does the frequency of the siren seem higher to you? 1. Case A 2. Case B 3. both 4. neither vsvs f vovo f’ v

61. Physics 101: Lecture 22, Pg 60 Doppler ACT A: You are driving along the highway at 65 mph, and behind you a police car, also traveling at 65 mph, has its siren turned on. B: You have both pulled over to the side of the road, and a police car turns on a siren and travels past you as they chase after someone else In which case does the frequency of the siren seem higher to you? 1. Case A 2. Case B 3. both 4. neither vsvs f vovo f’ v

62. Physics 101: Lecture 22, Pg 61Summary Sound travels as fast as the medium allows it’s measured by wavelength and frequency Two sounds close but not perfect make beats You hear a higher or lower pitch when sound moves closer or further away Resonance is the resounding of natural frequencies or harmonics creating timbre

63. Physics 101: Lecture 22, Pg 62 That’s all folks!