1. At which position(s) will the child hear the same frequency as that heard by a stationary observer standing next to the whistle?

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1 Name: Date: Use the following to answer question 1: The diagram shows the various positions of a child in motion on a swing. Somewhere in front of the child a stationary whistle is blowing. 1. At which position(s) will the child hear the same frequency as that heard by a stationary observer standing next to the whistle? A) at both A and D D) at C when moving toward B B) at B when moving toward A E) at C when moving toward D C) at B when moving toward C 2. A periodic wave is produced on a stretched string. Which one of the following properties is not related to the speed of the wave? A) frequency B) amplitude C) period D) wavelength E) tension in the string Use the following to answer question 3: The diagram shows the various positions of a child in motion on a swing. Somewhere in front of the child a stationary whistle is blowing. Page 1

2 3. At which position(s) will the child hear the lowest frequency for the sound from the whistle? A) at both A and D D) at C when moving toward B B) at B when moving toward A E) at C when moving toward D C) at B when moving toward C 4. The speed of sound in a certain metal block is m/s. The graph shows the amplitude (in meters) of a wave traveling through the block versus time (in milliseconds). What is the wavelength of this wave? A) 0.5 m B) 1.5 m C) 3.0 m D) 4.0 m E) 6.0 m 5. The tension in a taut rope is increased by a factor of 9. How does the speed of wave pulses on the rope change, if at all? A) The speed remains the same. D) The speed is increased by a factor of 3. B) The speed is reduced by a factor of 3. E) The speed is increased by a factor of 9. C) The speed is reduced by a factor of During a typical workday (eight hours), the average sound intensity arriving at Larry's ear is W/m 2. If the area of Larry's ear through which the sound passes is m 2, what is the total energy entering each of Larry's ears during the workday? A) J B) J C) J D) J E) J 7. A person was talking in a small room; and the sound intensity level is 60 db everywhere within the room. Now, there are eight people talking in similar manner simultaneously in the room, what is the sound intensity level? A) 60 db B) 79 db C) 74 db D) 64 db E) 69 db Page 2

3 8. A train moving at a constant speed is passing a stationary observer on a platform. On one of the train cars, a flute player is continually playing the note known as concert A (f = 440 Hz). After the flute has passed, the observer hears the sound with a frequency of 415 Hz. What is the speed of the train? The speed of sound in air is 343 m/s. A) 7.3 m/s B) 12 m/s C) 21 m/s D) 37 m/s E) 42 m/s 9. At a distance of 5.0 m from a point sound source, the sound intensity level is 110 db. At what distance is the intensity level 95 db? A) 5.0 m B) 7.1 m C) 14 m D) 28 m E) 42 m 10. The decibel level of a jackhammer is 130 db relative to the threshold of hearing. Determine the decibel level if two jackhammers operate side by side. A) 65 db B) 130 db C) 133 db D) 144 db E) 260 db Use the following to answer question 11: A periodic transverse wave is established on a string such that there are exactly two cycles traveling along a 3.0-m section of the string. The crests move at 20.0 m/s. 11. What is the frequency of the wave? A) 0.67 Hz B) 1.33 Hz C) 13 Hz D) 30 Hz E) 57 Hz 12. A stationary railroad whistle is sounded. An echo is heard 5.0 seconds later by the train's engineer. If the speed of sound is 343 m/s, how far away is the reflecting surface? A) 68 m B) 140 m C) 860 m D) 1700 m E) 2000 m 13. Two pulses of identical shape travel toward each other in opposite directions on a string, as shown in the figure. Which one of the following statements concerning this situation is true? A) The pulses will reflect from each other. B) The pulses will diffract from each other. C) The pulses will interfere to produce a standing wave. D) The pulses will pass through each other and produce beats. E) As the pulses pass through each other, they will interfere destructively. Page 3

4 14. Four standing wave segments, or loops, are observed on a string fixed at both ends as it vibrates at a frequency of 140 Hz. What is the fundamental frequency of the string? A) 23 Hz B) 28 Hz C) 35 Hz D) 47 Hz E) 70 Hz Use the following to answer question 15: The figures show standing waves of sound in six organ pipes of the same length. Each pipe has one end open and the other end closed. Note: some of the figures show situations that are not possible. 15. Which one of the pipes emits sound with the highest frequency? A) 1 B) 2 C) 3 D) 4 E) For a diffraction horn loudspeaker, the sound emerges through a rectangular opening. The width of a diffraction horn is 0.18 m. If the speed of sound in air is 343 m/s, at what frequency is the diffraction angle equal to 35? A) 3300 Hz B) 4800 Hz C) 6300 Hz D) 7700 Hz E) 9200 Hz Use the following to answer question 17: A 3.00-m long string sustains a three-loop standing wave pattern as shown. The wave speed is m/s. 17. What is the lowest possible frequency for standing waves on this string? A) 50.0 Hz B) 33.3 Hz C) 25.0 Hz D) 16.7 Hz E) 8.33 Hz Page 4

5 18. Two timpani (tunable drums) are played at the same time. One is correctly tuned so that when it is struck, sound is produced that has a wavelength of 2.20 m. The second produces sound with a wavelength of 2.08 m. If the speed of sound is 343 m/s, what beat frequency is heard? A) 7 beats/s B) 9 beats/s C) 11 beats/s D) 13 beats/s E) 15 beats/s 19. A guitar string has a linear density of kg/m and a length of m. The tension in the string is 52.0 N. When the fundamental frequency of the string is sounded with a Hz tuning fork, what beat frequency is heard? A) 6 Hz B) 4 Hz C) 12 Hz D) 8 Hz E) 2 Hz Use the following to answer question 20: The figures show standing waves of sound in six organ pipes of the same length. Each pipe has one end open and the other end closed. Note: some of the figures show situations that are not possible. 20. Which one of the pipes is resonating in its third harmonic? A) 1 B) 2 C) 3 D) 4 E) Which one of the following statements is true concerning the points on a string that sustain a standing wave pattern? A) All points vibrate with the same energy. B) All points undergo the same displacements. C) All points vibrate with different frequencies. D) All points vibrate with different amplitudes. E) All points undergo motion that is purely longitudinal. Page 5

6 Use the following to answer question 22: Vibrations with frequency Hz are established on a 1.33-m length of string that is clamped at both ends. The speed of waves on the string is m/s. 22. How far from either end of the string does the first node occur? A) 0.17 m B) 0.33 m C) 0.49 m D) 0.66 m E) 0.75 m 23. A cylindrical tube sustains a fundamental frequency f1 when both of its ends are open. A second cylindrical tube with one end closed has the same fundamental frequency. What is the ratio of the length of the second tube to that of the first, L2/L1? A) 0.5 B) 4 C) 2 D) 0.25 E) 1 Use the following to answer question 24: Consider the figures depicting rectangular pulses on a string. 24. Which pulses must be superimposed to give the situation shown in 5. A) 1 and 2 B) 1 and 3 C) 2 and 4 D) 1, 2, and 4 E) 2, 3, and 4. Use the following to answer question 25: A string with a length of 2.5 m has two adjacent resonances at frequencies 112 Hz and 140 Hz. 25. Determine the fundamental frequency of the string. A) 14 Hz B) 28 Hz C) 42 Hz D) 56 Hz E) 70 Hz Page 6

7 Answer Key 1. A 2. B 3. D 4. E 5. D 6. D 7. E 8. C 9. D 10. C 11. C 12. C 13. E 14. C 15. B 16. A 17. D 18. B 19. A 20. D 21. D 22. B 23. A 24. B 25. B Page 7