Physics 011

MC#12

Chapter 12: Sound

 1 At 0oC, approximately how long does it take sound to travel 5.00 km? 15 s 30 s 45 s 60 s 2 In which medium will the speed of sound of frequency 103 Hz be greatest? air at 25oC water at 25oC jello at 25oC iron metal at 25oC 3 The fog horn of a ship echoes off an iceberg in the distance. If the echo is heard 5.00 seconds after the horn is sounded and the air temperature is - 50.0oC, how far away is the iceberg? 200 m 750 m 825 m 900 m 4 A man drops a metal probe down a deep well drilling shaft that is 3920 meters deep. If the temperature is 25oC, which is the closest estimate of how long it takes to hear the echo after the probe is dropped? 5.0 s 10 s 20 s 40 s 5 What is the intensity, in W/m2, of sound with a sound level of 20 dB? 10-12 W/m2 10-10 W/m2 1 W/m2 10 W/m2 6 What is the sound level of a wave with an intensity of 10-3 W/m2? 30 dB 60 dB 90 dB 120 dB 7 A stereo receiver has a power output of 50 W at a frequency of 1000 Hz. If the frequency is decreased to 100 Hz, the output decreases by 10 dB. What is the power output at 10 Hz? 5.0 W 10 W 50 W 100 W 8 If the intensity of a sound is increased by a factor of 10, the sound level is increased by ___ dB. 0.10 1.0 2.0 3.0 10 20 9 If the sound level is increased 20 dB, the intensity of the sound is increased by a factor of ___. 2 10 20 50 100 200 10 While tuning a guitar, one finds it necessary to tighten one of the strings of the guitar. As a result of tightening the string, . . . . . . the speed of a transverse wave on the string ___. increases decreases remains constant is unpredictable 11 While tuning a guitar, one finds it necessary to tighten one of the strings of the guitar. As a result of tightening the string, . . . . . . the wavelength of the longest wavelength standing wave which can exist on the string ___. remains constant increases decreases is unpredictable 12 While tuning a guitar, one finds it necessary to tighten one of the strings of the guitar. As a result of tightening the string, . . . . . . the frequency of the fundamental frequency of the string ___. decreases remains constant increases is unpredictable 13 The longest wavelength that can exist as a standing wave on a string 2.0 m long that is tied at both ends is ___ m. 0.50 1.0 2.0 4.0 8.0 some other value 14 The longest wavelength that can exist as a standing wave in an organ pipe 2.0 m long that is open on one end and closed on the other is ___ m. 0.50 1.0 2.0 4.0 8.0 some other value 15 The longest wavelength that can exist as a standing wave in an organ pipe 2.0 m long that is open on both ends is ___ m. 0.50 1.0 2.0 4.0 8.0 some other value 16 Two pulses, exactly out of phase, travel towards each other along a string as indicated below: The phenomenon that occurs when the pulses meet is called refraction. reflection. diffraction. interference. 17 If two frequencies emitted from two sources are 48 and 54 vibrations per second, how many beats per second are heard? 3 6 9 12 18 The frequency heard by a detector is higher than the frequency emitted by the source. Which of the statements below must be true? The source must be moving away from the detector. The source must be moving towards the detector. The source and the detector may be moving towards each other. The source may be moving away from the detector. 19 You are caught in a narrow median of a street and a small sports car is approaching you at a constant speed of 40 m/s. The engine of the car is emitting a sound at a constant frequency of 100 Hz as heard by the driver of the car. You measure the speed of the sound of the engine and determine it to be 340 m/s on this windless day. The pitch of the sound of the engine that you hear as the car approaches you is ___ 100 Hz. more than equal to less than incomparable, without additional information, with 20 You are caught in a narrow median of a street and a small sports car is approaching you at a constant speed of 40 m/s. The engine of the car is emitting a sound at a constant frequency of 100 Hz as heard by the driver of the car. You measure the speed of the sound of the engine and determine it to be 340 m/s on this windless day. After the car passes you and continues up the street with the same constant speed, you again measure the speed of the engine sound and find it to be ___ 340 m/s. less than more than equal to incomparable, without additional information, with