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. : "Sound"

Standing Waves

Q- One of the 63.5 cm long strings of an ordinary guitar is tuned to produce the not B (frequency 245 Hz) when vibrating in its fundamental mode.

(a) find the speed of the transverse wave on this string.

(b) If the tension in the string is doubled, what will be the new fundamental frequency of the…

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Sound: Intensity and Loudness

Q- A loudspeaker emits a power of 100 W and can be considered as appoint source. Find the sound intensity and sound level in dB at a distance of 10 m from the speaker. How close would you have to be to the speaker for the sound level to be at the threshold of pain (120 dB)?  (The threshold of hearin…

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Sound: Resonance

Q- A closed end organ pipe is sounded near a guitar causing one of the strings to vibrate with large amplitude. The string is 80% as long as the organ pipe. If both vibrate at their fundamental frequency, calculate the ratio of the speed of wave on the string to the speed of sound in air.

Solution…

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Sound: Intensity and Loudness

Q- When a pin of mass 0.120 g is dropped from a height of 0.80 m and 0.05% of its energy is converted into a sound pulse with a duration of 0.1 s. 

(a) Estimate the range at which the dropped pin can be heard if the minimum audible intensity is 10-11 W/m2.

(b) Your result in (a) is much too larg…

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Transverse Waves: Stretched Strings

Q- A 1.5 m long rope is stretched between two supports with a tension that makes the speed of transverse waves on the rope 48 m/s. The rope is made to vibrate, what will be the wavelength an frequency of

(a) the fundamental and

(b) the fourth harmonic?  

Solution:

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Transverse Waves

Q- One of the 63.5 cm long guitar wire is tuned  to produce note B (245 Hz) when vibrating in its fundamental mode.

(a) Find the speed of the transverse wave on the string.

(b) If the tension in the string is doubled, what will be the new fundamental frequency?

Solution:

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Sound Waves: Wave-front

Q- A sound source is located somewhere along the x-axis. Experiments show that the same wave front simultaneously reaches listeners at x = -6 m and x = +8.0 m.

(a) What is the x co ordinate of the source?

(b) A third listener is positioned along the positive y-axis. What is her y coordinate if the…

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Sound Waves: Interference

Q- Two in-phase loudspeakers are located at (x, y) coordinates (-2.5 m, +2.0 m) and (-2.5 m, -2.0 m). They emit identical sound waves with a 1.6 m wavelength and amplitude a. Determine the amplitude A of the sound at the five positions on the y-axis (x = 0) with the y values 0, 0.5 m, 1.0 m, 2.0 m.

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Standing waves

Q- A 1.5 m long string is stretched between two supports with a tension such that the speed of the transverse wave on the string is 48 m/s. The string is made to vibrate. Find the wavelength and frequency of

  1. Fundamental note, and
  2. The fourth harmonic. 

 Solution:

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Waves

Q- Figure shows snapshot graph at t = 0 of two waves approaching each other at 1 m/s. Draw six snapshots graphs showing the string at 1 s intervals from t = 1 s to t = 6 s.

Solution:

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Standing Waves

Q- A 78 cm long guitar string with a linear density of 1.0 g/m is under 225 N tension. It is plucked and vibrates at its fundamental frequency. What is the wavelength of the sound wave that reaches your ear in a 20°C room?

Solution:

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Waves

Q- Figure shows a snapshot graph of a wave traveling to the right along a string at 55 m/s. Each interval on the vertical axis corresponds to 0.5 cm. At this instant, what is the velocity of points 1, 2, and 3 on the string?

Solution:

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Waves

Q- Earthquakes are essentially sound waves traveling through the earth. They are called seismic waves. Because the earth is solid, it can support both longitudinal and transverse seismic waves. These travel at different speeds. The speed of longitudinal waves, called P waves, is 8000 m/s. Transverse…

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Sound Waves: Interference

Q- A riverside warehouse has two open doors and its walls are lined with sound absorbing material. A boat on the river sounds its horn. To a person A on the perpendicular bisector of the doors, at a distance 150 m from the doors, sound is loud and clear while to a person B, 30 m sideways from A, the…

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Waves on string

Q- An apparatus similar to the one used in lab uses an oscillating motor at one end to vibrate a long rope with frequency f = 35 Hz and amplitude A = 0.25 m. The rope is held at constant tension by hanging a mass on the other end. The length of the rope is adjusted to form loops.The rope has mass de…

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Standing Waves

Q- What are the three longest wavelengths for standing sound waves in a 121 cm long tube that is

(a) open at both ends

(b) Open at one end and closed at the other.

Solution:

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Wave Motion

Q- In the oceans, whales communicate by sound transmission through the water. A whale emits a sound of 60 Hz to tell a wayward calf to catch up to the pod. The speed of sound in water is about 1500 m/s.

(a) How long does it take the sound to reach the calf if he is 1.46 km away?

(b) What is the wa…

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Sound Waves

Q- Figure shows a snapshot graph at t = 0 s of a 30.0 Hz wave traveling to the left. Each interval on the vertical axis corresponds to 5 mm. 

(a) What is the wave speed?

(b) What is the phase constant of the wave?

(c) Write the displacement equation for this wave.

Solution:

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Wave Motion

Q- The displacement of a wave traveling in the negative y-direction is D(y, t) = (5.0 cm) sin (5.5y + 74t) where y is in m and t is in s. What are each of the following for this wave?

(a) Frequency

(b) Wavelength

(c) Speed

Solution:

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Sound Waves: Doppler Effect And Beats

Q- A trumpet player is on a flatcar drawn by a locomotive and another player is near tracks. If each player blows a 440 Hz note, and if there are 4 beats/s as they approach each other, what is the speed of the flatcar? (Speed of sound in air is 340 m/s)

Solution:

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