# A source of sound emits waves at a frequency f= 650 Hz. An observer is located at a distance d= 170 m from the source. Use u=340 m/s for the speed of sound. (a) Assume completely still air. How many

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1. ## Science--HELP!!

1. In which of the following situations is a sound wave most likely to travel through air? A) An alarm clock rings in a vacuum. B) A giant star explodes. C) A grasshopper eats a leaf. D) An astronaut uses tools in space. 2. Which of the following factors

A source emits sound uniformly in all directions. There are no reflections of the sound. At a distance r1 from the source the sound is 6.5 dB louder than it is at a distance r2 from the source. What is the ratio r1/r2?

A source emits sound uniformly in all directions. There are no reflections of the sound. At a distance of 12 m from the source, the intensity of the sound is 1.7 × 10-3 W/m2. What is the total sound power P emitted by the source? Would I do 1.7e^-3 (12) ?

4. ## Physics

Blood flow rates in the umbilical cord can be found by measuring the Doppler shift of the ultrasound signal reflected by the red blood cells. If the source emits a frequency f, what is the measured reflected frequency fR? Assume that all of the red blood

5. ## Physics

A source passing a stationary observer is emitting a frequency of 560 Hz. If the speed of sound is 345 m/s, what must speed of the source be if the frequency speed is 480 hz? Here's what I've tried... Fo=480 Hz FObs = 480 + 560 VSource = ?(x) Vsound = 345

6. ## physics

A source of sound (1000 Hz) emits uniformly in all directions. An observer 3.19 m from the source measures a sound level of 39.2 dB. Calculate the average power output of the source.

7. ## physics

A stereo speaker represented by P in Figure 13-22 emits sound waves with a power output of 130.0 W. What is the intensity of the sound waves at point x when r = 7.8 m? W/m2

8. ## physics

A train moving at a constant speed is passing a stationary observer on a platform. a flute player is playing a note with frequency of 940Hz. after the flute has passed, the observer hears the sound frequency of 915Hz. What is the speed of the train? The

9. ## Physics

A Doppler blood flow meter emits ultrasound at a frequency of 5.0 MHz. What is the beat frequency between the emitted waves and the waves reflected from blood cells moving away from the emitter at 0.15m/s? Assume that v_sound=1540m/s in blood.

10. ## physics

to an observer the pitch of the stationary source of the sound appears to be reduced by 20% if speed of sound is 340m/s then sped and direction of 5he observer is options 1.68 m/s away from the observer 2.96 m/s away from the observer

11. ## science

Sound waves are traveling through the air. Every ½ second, the sound waves pass a detector. Which of the following choices correctly describes the period and frequency of these waves? The period is 2 s, and the frequency is 2 Hz. The frequency is ½

12. ## physics

A stationary motion detector sends sound waves of frequency 0.0953 MHz toward a truck approaching at a speed of 42.6 m/s. What is the frequency of the waves reflected back to the detector? (Take the speed of sound to be 343 m/s.)

13. ## physics pls help

A sound source producing 1.00-{\rm kHz} waves moves toward a stationary listener atone-half the speed of sound. The frequency that the listener will hear is2000 Hz. when the source is stationary and the listener moves towardthe source at one-half the speed

14. ## Physics

as observer travelling with a constant velocity of 20m/s passes close to a stationary source of sound and noticed that there is a change of frequency of 50Hz as he passes the source. What is the frequency of the source? (speed of sound in air=340m/s)

15. ## Physics

Ultrasound reflected from an oncoming bloodstream that is moving at 30 cm/s is mixed with the original frequency of 1.3 MHz to produce beats. What is the beat frequency? (Velocity of sound in blood = 1540 m/s.) Beat frequency = Hz HELP: This problem

16. ## physics

A stereo speaker represented by P in the figure below emits sound waves with a power output of 114 W. What is the intensity of the sound waves at point x when r = 11.8 m?

17. ## Science

1. A weatherman reports, "the storm waves are about 2 meters high and about 35 meters apart. "what properties of waves is the reporter describing? Frequency and wavelength Wavelength and wave speed***** Amplitude and wavelength Amplitude and frequency 2.

18. ## Physics

A bell with a fundamental frequency of 880 Hz is moving toward an observer at 3.5 m/s. If the speed of sound is 343 m/s, what pitch would be heard by the observer

19. ## physics

The siren on an ambulance is emitting a sound whose frequency is 2421 Hz. The speed of sound is 343 m/s. (a) If the ambulance is stationary and you (the "observer") are sitting in a parked car, what are the wavelength and the frequency of the sound you

20. ## physics

Ige confused, the truck driver sound the horn of the truck, which has a frequency of 260HZ. The speed of sound in air is 340m/s. an observer hears the sound while traveling in a bus toward the truck at a speed of 30m/s. a) what is the wavelength of the

21. ## Physics

An observer traveling with a constant velocity of 20m/s passes close to a stationary source of sound and noticed that there is a change of frequency of 50Hz as he passes the source.What is the frequency of the source? (Speed of sound in air=340 m/s)

22. ## physics

A stereo speaker emits sound waves with a power output of 100W. (a) find the intensity 10.0m from the source. B) find the intensity level in decibels, at this distance. C) at what distance would you experience the sound at the threshold of pain,120dB?

23. ## physics

A train moving at a constant speed is passing a stationary observer on a platform. a flute player is playing a note with frequency of 940Hz. after the flute has passed, the observer hears the sound frequency of 915Hz. What is the speed of the train? The

24. ## Science

1. A weatherman reports, "the storm waves are about 2 meters high and about 35 meters apart. "what properties of waves is the reporter describing? Frequency and wavelength Wavelength and wave speed***** Amplitude and wavelength Amplitude and frequency 2.

25. ## Science

1. A weatherman reports, "the storm waves are about 2 meters high and about 35 meters apart. "what properties of waves is the reporter describing? Frequency and wavelength Wavelength and wave speed Amplitude and wavelength Amplitude and frequency 2. Sound

26. ## Science

6. Sonar is used to inspect pipelines and bridge foundations. In this scenario, sonar takes advantage of the fact that (1 point) A.sound waves can reflect.*** B.sound waves can diffract. C.sound waves can spread out. D.sound waves can refract.

27. ## Physics

Three sources of sound are distributed along a line, as shown in the figure. v is the speed of sound. Source A is at rest, and it emits sound waves with a frequency of 480 Hz. Source B is traveling at v/5 to the right, and it emits sound waves with a

A sound of 7 kHz frequency is well within the normal hearing range of most people. True. False.

29. ## physics

1)As a sound source moves away from a stationary observer, the number of waves will. decrease 2)How fast should a car move toward you for the car's horn to sound 2.88% higher in frequency than when the car is stationary? The speed of sound is 343 m/s.

30. ## physics

A siren mounted on the roof of a firehouse emits sound at a frequency of 900 Hz. A steady wind is blowing with a speed of 15 m/s. Take the speed of sound in calm air to be 343 m/s. (c) Firefighters are approaching the siren from various directions at 15.0

31. ## Physics

1. A train whistle has a frequency of 1000 Hz. If the train is speeding at a velocity of 60 km/h past a stationary railroad crossing attendant, what is the apparent frequency a) as the train approaches him, b) as it moves away from him? Assume speed of

32. ## Physics

An observer is located directly between two speakers, located 20m apart. The speakers are in phase with each other, and both are emitting a sound with a frequency of 60Hz. How far away from the centre should the observer move to get the first destructive

33. ## physics

An observer detects an apparent frequency of 505 hz coming from a 500 hz source. Which is true? a. the observer is moving due east, away from the stationary source b. the source is moving due west, away from the stationary observer c. the souce and the

34. ## phys

An observer detects an apparent frequency of 505 hz coming from a 500 hz source. Which is true? a. the observer is moving due east, away from the stationary source b. the source is moving due west, away from the stationary observer c. the souce and the

35. ## physics

An acoustic burglar alarm consists of a source emitting waves of frequency 28.0 kHz. What is the beat frequency between the source waves and the waves reflected from an intruder walking at an average speed of 0.095 m/s directly away from the alarm?

36. ## when the energy of a sound wave is transferred to

when the energy of a sound wave is transferred to a particle of a medium and causes it to vibrate and generate heat, the sound wave is a. reflected b. refracted c. absorbed d. transmitted The pitch of the siren of a moving fire truck changes from high to

37. ## physics

A speeding car is pulling away from a police car. The police car is moving at 30 m/s. The radar gun in the police car emits an electromagnetic wave with a frequency of 20.0 x 10^9 Hz. The wave reflects from the speeding car and returns to the police car

38. ## physics

a flying bat emits squeaks of frequency 80 kHz.if a stationary observer hears the frequency of the squeaks as 78kHz,is the bat moving towards or away from the observer?determine the speed at which the bat is flying.

39. ## Physics

This time I have two questions: #1.A recording engineer works in a soundproofed room that is 49.7 dB quieter than the outside. If the sound intensity in the room is 2.66 x 10-10 W/m2, what is the intensity outside? #2.A listener increases his distance from

40. ## physic

A source of sound emits waves at a frequency 650 Hz. An observer is located at a distance 190 m from the source. Use m/s for the speed of sound. (a) Assume completely still air. How many wavefronts (full waves) are there between the source and the

41. ## physics(URGENT!!!!!)

A source of sound emits waves at a frequency f= 650 Hz. An observer is located at a distance d= 170 m from the source. Use u=340 m/s for the speed of sound. (a) Assume completely still air. How many wavefronts (full waves) N are there between the source

42. ## physics

A train at rest emits a sound at a frequency of 1089 Hz. An observer in a car travels away from the sound source at a speed of 30.7 m/s. What is the frequency heard by the observer? Assume the speed of sound in air to be 343 m/s.

43. ## physics

1)As a sound source moves away from a stationary observer, the number of waves will. A)increase B)decrease C)remain the same D)need to know the speed of the source (answer:decrease.) As the detector recedes from the source, the relative velocity is

44. ## physics

1)As a sound source moves away from a stationary observer, the number of waves will. decrease 2)How fast should a car move toward you for the car's horn to sound 2.88% higher in frequency than when the car is stationary? The speed of sound is 343 m/s.

45. ## phy

Doppler ultrasound is used to measure the speed of blood flow. If the speed of the red blood cells is v, the speed of sound in blood is u, the ultrasound source emits waves of frequency f, and we assume that the blood cells are moving directly toward the

46. ## physics

a source of sound id traveling towards a stationary observer .The frequency of sound is heard by the observer is 25% more that the actual frequency.If the speed of sound is v,that of the source is options: 1.v/4 2.v/5

47. ## science

apparent change in wavelength of sound waves is 2.5cm when the source of sound is approaching stationary listener with velocity 8cm/s.Apparent decrease in the frequency of source when observer recedes from the same source at rest with a velocity of 30m/s

48. ## physics

1.calculate th speed of waves in water that are 0.4m apart and have a frequency of 2hz? 2. sound waves travel at approximately 340m/s what is the wavelength of a sound with a frequency of 20Hz? what is the wavelength of a sound with a frequency of 20 kHz?

49. ## Physics

Two eagles fly directly toward one another, the first at 13 m/s and the second at 21 m/s. Both screech, the first emitting a frequency of 3200 Hz and the second, a frequency of 3800 Hz. What frequencies do they hear if the speed of sound is 345 m/s? (Tip:

50. ## physics

A source of sound (1200 Hz) emits uniformly in all directions. An observer 2.99 m from the source measures a sound level of 41.1 dB. Calculate the average power output of the source.

51. ## physics

A source of sound (1200 Hz) emits uniformly in all directions. An observer 2.99 m from the source measures a sound level of 41.1 dB. Calculate the average power output of the source.

52. ## physics

A source of sound (1200 Hz) emits uniformly in all directions. An observer 2.99 m from the source measures a sound level of 41.1 dB. Calculate the average power output of the source.

53. ## Physics

A source of sound (1140Hz) emits uniformly in all directions. An observer 3.09m from the source measures a sound level of 38.2dB. Calculate the average power output of the source.

54. ## physical

You are traveling in a car toward a hill at a speed of 42.1 mph. The car's horn emits sound waves of frequency 251 Hz, which move with a speed of 343 m/s. a) Determine the frequency with which the waves strike the hill. b) What is the frequency of the

55. ## physics

You are traveling in a car toward a hill at a speed of 40.8 mph. The car's horn emits sound waves of frequency 243 Hz, which move with a speed of 340 m/s.The frequency with which the waves strike the hill is 254.7Hz and the frequency of the reflected sound

56. ## physics

An observer rides with a moving sound source directly toward a large vertical wall. The vehicle has a constant speed of 10m/s and the source has a frequency of 150Hz. What beat frequency is heard by the observer as a result of the combination of the direct

57. ## Physics 20

A 2.50-kg Pendulum is attatched to a string 11.4m stringis pulled aside until it is.386m above its lowest position and released. The pendulum is designed to emit sound waves at a frequency of 440 Hz; However, as it swings toward and away from an observer,

You are traveling in a car toward a hill at a speed of 40.8 mph. The car's horn emits sound waves of frequency 243 Hz, which move with a speed of 340 m/s.The frequency with which the waves strike the hill is 254.7Hz and the frequency of the reflected sound

You are traveling in a car toward a hill at a speed of 40.8 mph. The car's horn emits sound waves of frequency 243 Hz, which move with a speed of 340 m/s.The frequency with which the waves strike the hill is 254.7Hz and the frequency of the reflected sound

60. ## Physics

1)As a sound source moves away from a stationary observer, the number of waves will. A)increase B)decrease C)remain the same D)need to know the speed of the source (answer:decrease.) As the detector recedes from the source, the relative velocity is

61. ## physics

An electronic point source emits sound isotropically at a frequency of 3000 Hz and a power of 34 watts. A small microphone has an area of 0.75 cm2 and is located 158 meters from the point source. a) What is the sound intensity at the microphone ? To find

62. ## Physics

Two sources of sound are located on the x axis, and each emits power uniformly in all directions. There are no reflections. One source is positioned at the origin and the other at x = +153 m. The source at the origin emits four times as much power as the

63. ## Physics

A source traveling at 100m/s emits sound waves of frquency 900hz ..what is the velocity of the sound ?

64. ## physics

a source emits 1700Hz frequency travelling at a speed of 70m/s. A detector is placed 200m away. What is the frequency detected by the detector when the source is closest to it? Also find the distance between them when the detector detects the frequency to

65. ## Physics

A stationary observer hears a sound with a frequency of 450 Hz from an approaching car. If the car emits the sound at a frequency of 360 Hz, what would be the speed of the car? (Speed of sound 340 m/s)

66. ## Physics - Waves

A speaker which produces a frequency of 400 Hz is moving away from an observer and towards a wall at 5 m/s when it is 23 degrees Celsius. What is the frequency of the sound that travels back to the observer? What is the frequency of the sound that travels

67. ## Physics

An airplane moves away from a stationary observer at 125 m/s and emits a frequency of 595 Hz on a day where the temperature is 25.0°C. What frequency does the observer hear?

68. ## DrBob222

As a sound source moves away from a stationary observer, the number of waves will. decrease

69. ## Waves-Science

I had a couple of questions on the topic of Waves-Sound and Light. 1. What is the source of all waves? *Vibration* 2. In one word, what is it that moves from source to receiver in a wave motion? *Energy* 3. Does the medium in which a wave travels move with

70. ## Intergarted Science

I had a couple of questions on the topic of Waves-Sound and Light. 1. What is the source of all waves? *Vibration* 2. In one word, what is it that moves from source to receiver in a wave motion? *Energy* 3. Does the medium in which a wave travels move with

71. ## physics

If the sound waves detected by the dector is the same as the frequency of the source, what can we conclude about the motion of the source and detector?

72. ## PHYSICS

A 50cm long hollow glass cylinder is open at both ends and is suspended in air. A source o sound that produces a pure frequency is placed close to one end of the tube. The frequency of the sound is slowly increased from a very low value. The tube is first

73. ## physics, doppler effect

"A source of sound of frequency f0 moves horizontally at constant speed u in the x direction at a distance h above the ground. An observer is situated on the ground at the point x=0 (the source passes over this point at t=0). Show that the signal received

74. ## Physics

Two speakers are 2m apart. An observer is 3m Infront of one speaker. a) if both are driven by a single oscillator at 300Hz, what is the phase difference at the observer b) what is the frequency closest to 300Hz for which the observer hear minimal

75. ## Science

I need to check my answers!! Which of these is not in the family a. sound b. light c. infrared radiation (answer) d. radio waves When an electric charge is shaken to and fro in quick succession, the vibrating charge emits a. infrasonic sound b. Ultrasonic

76. ## Science

I need to check my answers!! Which of these is not in the family a. sound b. light c. infrared radiation (answer) d. radio waves When an electric charge is shaken to and fro in quick succession, the vibrating charge emits a. infrasonic sound b. Ultrasonic

77. ## Physics

A source produces 2000 sound waves in 4 seconds. The distance between two consecutive compressions is 55cm. Find the frequency, wavelength and speed of sound wave

78. ## Physics

A speaker which produces a frequency of 312 Hz is moving away from an observer and towards a wall at 3 m/s when it is 30 degrees Celsius. What is the frequency of the sound that travels directly to the observer? What is the frequency of the sound that

79. ## physics

An airplane traveling at v = 163 m/s emits a sound of frequency 1730 Hz. At what frequency does a stationary listener hear the sound as the plane approaches? Use 340 m/s for the speed of the sound and answer in Hz.

80. ## physics

An airplane traveling at v = 152 m/s emits a sound of frequency 1850 Hz. At what frequency does a stationary listener hear the sound as the plane approaches? Use 340 m/s for the speed of the sound and answer in Hz.

What approximate change in decibels does an observer experience form a sound source if the observer moves to a new location that is 67% as far from the source? 23 -23 40 2.76 -2.76 1.94 -1.94 2.57 -2.57 0 do I multiply .67 times 10 log .67?

82. ## Physical Science 9th grade

Could someone please explain how I do this or provide a link explaining how. I am very confused. 1) a) Name 2 properties of waves that change if the wave changes media. b) Name a property that does NOT change when it changes media. 2) If the wavelength of

83. ## Physics _ College

A 50 cm long hollow glass cylinder is open at both ends and is suspended in air. A source of sounds that produces a pure frequency is placed close to one end of the tube. The frequency is placed close to one end of the tube. The frequency of the sound

84. ## Physics

A person is initially 8 m from a point sound source which emits energy uniformly in all direction at a constant rate. If the intensity of the source is to be halved but the sound is to be as loud as before, what distance should the person be from the

85. ## Physics

A small omni directional source of noisy sound emits uniformly with a power of 40W.Determine the distance from the source for which the sound level is 90dB. Calculate also the intensity level at a point 100m from the source. (if there is no absorption)

86. ## physics

if a man moving away with the speed of 0.5 of sound from a stationary sound source producing a sound of frequency , he would hear a sound of frequency

87. ## Physical Science

I need help with a few of these questions: 1.Which of the following waves are mechanical waves? A.light waves B.microwaves C.radio waves D.sound waves I think it's D? 2.Which gives the frequency of the wave in terms of its peaks? A.the height of the

88. ## Physics

An observer is located directly between two speakers located 20 metres apart.Speakers are in phase and both are emitting a sound of 60Hz.How far away from the centre should the observer move to get the first destructive interference?

89. ## DrBob222

A car moving at 16.0 m/s, passes an observer while its horn is pressed. Find the difference between the frequencies of sound heard when the car approaches and when it recedes from the stationary observer. The velocity of sound is 343 m/s and the frequency

90. ## Physics!!

A car moving at 16.0 m/s, passes an observer while its horn is pressed. Find the difference between the frequencies of sound heard when the car approaches and when it recedes from the stationary observer. The velocity of sound is 343 m/s and the frequency

91. ## physics

NEED HELP WITH ONLY PART C Two 135.1.0-W speakers, A and B, are separated by a distance D = 3.6 m. The speakers emit in-phase sound waves at a frequency f = 11800.0 Hz. Point P1 is located at x1= 4.50 m and y1 = 0 m; point P2 is located at x2 = 4.50 m and

92. ## Science

1. A weatherman reports, "the storm waves are about 2 meters high and about 35 meters apart. "what properties of waves is the reporter describing? Frequency and wavelength Wavelength and wave speed***** Amplitude and wavelength Amplitude and frequency 2.

93. ## Physics

Two speakers are 2m apart. An observer is 3m Infront of one speaker. a) if both are driven by a single oscillator at 300Hz, what is the phase difference at the observer b) what is the frequency closest to 300Hz for which the observer hear minimal sound?

94. ## Physics

As the frequency of sound waves increases, the wavelength of the sound waves decreases true or false?

95. ## PHYSICS

a violin string emits sound of freqency 510Hz.how for will be the sound waves reach when string completes 250vibration?the velocity of sound is 340M/S.

96. ## physical

a police siren emits a sinusoidal wave with frequency f=300hz.the speed of sound is 340ms. find the wave lenght of the waves if the siren is at rest in the air

97. ## Physics

The note D above middle C has a frequency of 294 cycles per second, and the note E has a frequency of 330 cycles per second. A driver of a moving car sounds the horn, which emits an E tone, but a stationary observer hears a D tone. Calculate the speed at

98. ## physic

The waves emitted from a source A is given by y1 = 6 sin π(20t – 0.5x) where y1, x and t are expressed in units of meter and seconds. (a) Determine the wavelength and the frequency of the radio waves. At the same time, source B generates waves y2 that

99. ## Physics doppler effect

A radar device emits microwaves with a frequency of 4.73E+9 Hz. When the waves are reflected from a van moving directly away from the emitter, the beat frequency between the source wave and the reflected wave is 751 beats per second. What is the speed of

100. ## science (physics)

1) Why is frequency an element needed in the sound industry? and 2) When there is a sound pressure level of two different sources with different frequencies, why do sound pressure levels have to be determined in each separate frequency? 1) The sound