Slide 1 / 51 Slide 2 / 51 Sound Multiple Choice Practice Problems Problems Slide 3 / 51 Slide 4 / 51 1 Two sound sources S 1 and S 2 produce waves with 2 Which of the following is a true statement about frequencies 500 Hz and 250 Hz. When we compare the speed of sound in three different materials: air, the speed of wave 1 to the speed of wave 2 the water, and steel? result is: A V air > V water > V steel A Twice as greater B V air > V water = V steel B One-half as greater C V air = V water < V steel C The same D V air < V water > V steel D Four times greater E V air < V water < V steel E One-fourth as greater Slide 5 / 51 Slide 6 / 51 3 A sound source S radiates a sound wave in all 4 A sound source S radiates a sound wave in all directions. The relationship between the distances directions. The relationship between the distances is SA = AB = BC = CD. Which of the following is SA = AB = BC = CD. Which of the following points oscillates at the highest frequency? points oscillates with the greatest intensity? A Point A A Point A B Point B B Point B C Point C C Point C D Point D D Point D All points have the E All points have the same intensity E same frequency
Slide 7 / 51 Slide 8 / 51 5 The loudness of a sound wave increases with 6 A sound wave travels from air into water. Which of increasing which of the following: the following doesn’t change? A Frequency A Frequency B Amplitude B Amplitude C Period C Speed of Particles D Wavelength D Wavelength E Speed of sound E Speed of sound Slide 9 / 51 Slide 10 / 51 7 A sound wave resonates in a tube with two open 8 The lowest frequency in an open tube is 300 Hz. ends. What are the wavelengths of the three What are the three following frequencies will lowest resonating frequencies generated in the resonate in the tube? tube? A 600Hz, 900Hz, 1200Hz A L, 2L, 3L B 100Hz, 200Hz, 400Hz B L, 2L, 2L/3 C 250Hz, 500Hz, 750Hz C L/2, L/3, L/5 D 150Hz, 450Hz, 850Hz D L/3, L/5, L/7 E 50Hz, 100Hz, 150Hz E 4L, 4L/3, 4L/5 Slide 11 / 51 Slide 12 / 51 9 The lowest frequency in an open tube is 200 Hz. 10 A sound wave resonates in an open pipe with a Which of the following frequencies will resonate in length of 2 m. What is the wavelength of the the tube? wave? A 50Hz A 0.5 m B 100Hz B 1.0 m C 150Hz C 1.5 m D 250 Hz D 2.0 m E 400Hz E 2.5 m
Slide 13 / 51 Slide 14 / 51 11 A sound wave resonates in an open pipe with a 12 A sound wave resonates in an open pipe with a length of 4 m. What is the resonating frequency? length of 3 m. What is the wavelength of the (V sound = 340 m/s) wave? A 85 Hz A 1.5 m B 170 Hz B 2.0 m C 340 Hz C 2.5 m D 510 Hz D 3.0 m E 680 Hz E 6.0 m Slide 15 / 51 Slide 16 / 51 13 A sound wave resonates in an open pipe with a 14 A sound wave resonates in a tube with one open length of 1.5 m. What is the resonating frequency? end. What are the wavelengths of the three lowest (V sound = 340 m/s) resonating frequencies generated in the tube? A 85 Hz A L, 2L, 3L B 170 Hz B L, 2L, 2L/3 C 340 Hz C L/2, L/3, L/5 D 510 Hz D L/3, L/5, L/7 E 680 Hz E 4L, 4L/3, 4L/5 Slide 17 / 51 Slide 18 / 51 15 The lowest frequency in a closed tube is 300 Hz. 16 The lowest frequency in a closed tube is 400 Hz. What are the three following frequencies will Which of the following frequencies will resonate in resonate in the tube? the tube? A 600Hz, 900Hz, 1200Hz A 500Hz B 100Hz, 200Hz, 400Hz B 1000Hz C 250Hz, 500Hz, 750Hz C 1200Hz D 900Hz, 1500Hz, 2100Hz D 2500 Hz E 50Hz, 100Hz, 150Hz E 3000Hz
Slide 19 / 51 Slide 20 / 51 17 Two sound sources generate pure tones of 70 Hz 18 A sound wave resonates in a closed pipe with a and 80 Hz. What is the beat frequency? length of 1.5 m. What is the wavelength of the wave? A 5Hz A 1.5 m B 10Hz B 2.0 m C 15Hz C 2.5 m D 20Hz D 3.0 m E 25Hz E 6.0 m Slide 21 / 51 Slide 22 / 51 19 A sound wave resonates in a closed pipe with a 20 A sound wave resonates in a closed pipe with a length of 3.5 m. What is the wavelength of the length of 2.5 m. What is the resonating frequency? wave? (V sound = 340 m/s) A 1.5 m A 85 Hz B 2.0 m B 170 Hz C 2.5 m C 340 Hz D 3.0 m D 510 Hz E 6.0 m E 680 Hz Slide 23 / 51 Slide 24 / 51 21 Two sound sources generate pure tones of 115 Hz 22 Two sound sources produce waves with slightly and 130 Hz. What is the beat frequency? different frequencies. What happens with the beat frequency if the frequency of the lowest tone increases? A 5Hz B 10Hz A Increases C 15Hz B Decreases D 20Hz C Stays the same E 25Hz D Increases and then decreases E Decreases and then increases
Slide 25 / 51 Slide 26 / 51 23 A sound source approaches a stationary observer 24 An airplane moves away from a stationary at a constant speed of 34 m/s. If the frequency of observer at a constant speed of 340 m/s. The the stationary source is 90 Hz, what is the frequency of the sound wave of the stationary frequency heard by the observer? airplane is 780 Hz. What is the frequency heard by the observer? (V sound = 340 m/s) A 90 Hz A 1560 Hz B 100 Hz B 780 Hz C 180 Hz C 390 Hz D 270 Hz D 195 Hz E 360 Hz E 0 Hz Slide 27 / 51 Slide 28 / 51 25 Two loudspeakers generate sound waves with 26 Two loudspeakers generate sound waves with frequencies of 680 Hz. What is the extra distance frequencies of 680 Hz. What is the extra distance traveled by the second wave if a stationary traveled by the second wave if a stationary observer detects no sound at point P? observer detects maximum intensity of sound at point P? A 0.75 m A 0.75 m B 1.2 m B 1.2 m C 1.5 m C 1.5 m D 1.6 m D 1.6 m E 2.0 m E 2.0 m Slide 29 / 51 Slide 30 / 51 27 A sound source moves at a constant velocity V obj and generates a sound wave. The speed of sound is V sound . Which of the following is true about the direction and magnitude of the source velocity? Direction Magnitude A To the right V obj > V sound Free Response B To the right V obj < V sound Problems C To the right V obj = V sound D To the left V obj > V sound E To the left V obj < V sound
Slide 31 / 51 Slide 32 / 51 1. Two loudspeakers separated by a distance d = 0.5 m are placed at a 1. Two loudspeakers separated by a distance d = 0.5 m are placed at a distance L = 2 m from y-axis. The loudspeakers generate waves with the distance L = 2 m from y-axis. The loudspeakers generate waves with the same frequency f = 1360 Hz and amplitude A. The waves oscillate in same frequency f = 1360 Hz and amplitude A. The waves oscillate in phase. When a microphone moves in parallel to y-axis it can detect phase. When a microphone moves in parallel to y-axis it can detect points with no sound or sound of maximum amplitude. (V sound = 340 m/s) points with no sound or sound of maximum amplitude. (V sound = 340 m/s) a. Determine the wavelength of the sound waves. a. Determine the wavelength of the sound waves. b. Determine the angular displacement between the central maximum and first-order maximum. c. Determine the distance from the origin to the first point where the microphone detects no sound. d. If the loudspeakers oscillate in anti-phase, what is the new distribution in the interference pattern? Slide 33 / 51 Slide 34 / 51 1. Two loudspeakers separated by a distance d = 0.5 m are placed at a 1. Two loudspeakers separated by a distance d = 0.5 m are placed at a distance L = 2 m from y-axis. The loudspeakers generate waves with the distance L = 2 m from y-axis. The loudspeakers generate waves with the same frequency f = 1360 Hz and amplitude A. The waves oscillate in same frequency f = 1360 Hz and amplitude A. The waves oscillate in phase. When a microphone moves in parallel to y-axis it can detect phase. When a microphone moves in parallel to y-axis it can detect points with no sound or sound of maximum amplitude. (V sound = 340 m/s) points with no sound or sound of maximum amplitude. (V sound = 340 m/s) c. Determine the distance from the origin to the first point where the b. Determine the angular displacement between the central maximum and microphone detects no sound. first-order maximum. Slide 35 / 51 Slide 36 / 51 2. A group of students in a physics lab perform a series of experiments with a set of tubes and tuning fork. In the first trial they use a tube which length can be extended. The length of the tube when sound resonates for the first time is 0.5 m. (V sound = 340 m/s) a. Determine the wavelength of the sound wave. b. Determine the frequency of the tuning fork. 1. Two loudspeakers separated by a distance d = 0.5 m are placed at a distance L = 2 m from y-axis. The loudspeakers generate waves with the same frequency f = 1360 Hz and amplitude A. The waves oscillate in In the second trial the students use a tube with a phase. When a microphone moves in parallel to y-axis it can detect constant length but they place in the tube a cork points with no sound or sound of maximum amplitude. (V sound = 340 m/s) stopper with the same diameter as the inner size of the tube. The cork can freely move from the left side d. If the loudspeakers oscillate in anti-phase, what is the new of the tube to the right. The frequency of the tuning distribution in the interference pattern? fork stays the same as it was determine in the first trial. c. Determine the minimum length L 0 of the left side of the tube when the air column resonates for the first time. d. What is the length L of the tube when the air column resonates for the second time? third time?
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