Exam 12: Sound

Two people are talking at a distance of 3.0 m from where you are, and you measure the sound intensity as $1.1 \times 10 ^ { - 7 } \mathrm {~W} / \mathrm { m } ^ { 2 }$ Another student is 4.0 m away from the talkers. Calculate a reasonable estimate for the sound intensity that the other student measures.

A standing wave of the third overtone is induced in a 1.2-m pipe that is open at one end and closed at the other end. The speed of sound in the pipe is 340 m/s. (a) How many antinodes are there in the standing wave pattern? (b) What is the frequency of the sound produced by the pipe in this situation?

What is the intensity level in decibels of a sound with intensity The threshold of human hearing is

A jet flies at 1.4 times the speed of sound. What is the half-angle of the conical shock wave formed?

A pipe that is 0.92 m long and open at both ends vibrates in the second overtone with a frequency of 584 Hz. What is the speed of sound in the air in this pipe?

An elephant can hear sound with a frequency of 15 Hz. What is the wavelength of this wave if the speed of sound in air is 343 m/s?

The intensity at a distance of 6.0 m from a source that is radiating equally in all directions is What is the power emitted by the source?

A certain factory whistle can be heard up to a distance of 9.8 km. Assuming that the acoustic output of the whistle is uniform in all directions, at what distance from the factory is the intensity level of the whistle sound equal to 25 dB? The threshold of human hearing is $1.0 \times 10 ^ { - 12 } \mathrm {~W} / \mathrm { m } ^ { 2 }$

A crying baby emits sound with an intensity of $8.0 \times 10 ^ { - 8 } \mathrm {~W} / \mathrm { m } ^ { 2 }$ Calculate a reasonable estimate for the intensity level from a set of quintuplets (five babies), all crying simultaneously at the same place? The lowest detectable intensity is $1.0 \times 10 ^ { - 12 } \mathrm {~W} / \mathrm { m } ^ { 2 }$

A certain glass window reduces the intensity level of the sound from 72 dB to 47 dB. By what factor is the acoustic power reduced by this glass window?

If the intensity level of one trombone is 70 dB, calculate a reasonable estimate for the intensity level of 76 trombones all playing simultaneously in the same place?

A long-term exposure to the sound of a riveting machine can cause your threshold of hearing to shift from 0 dB to 30 dB. What is the sound intensity of a 30-dB sound? The normal lowest detectable intensity is $1.0 \times 10 ^ { - 12 } \mathrm {~W} / \mathrm { m } ^ { 2 }$

An organ pipe that is 1.75 m long and open at both ends produces sound of frequency 303 Hz when resonating in its second overtone. What is the speed of sound in the room?

A certain siren radiates sound uniformly in all directions. At a distance of 17 m from the siren, the intensity level is 49 db. How many watts of power does this siren put out? The threshold of human hearing is $1.0 \times 10 ^ { - 12 } \mathrm {~W} / \mathrm { m } ^ { 2 }$

An organ pipe closed at one end and open at the other end has two successive harmonics with frequencies of 2170 Hz and 2790 Hz. What is the fundamental frequency of the pipe?

A factory siren indicating the end of a shift has a frequency of 80 Hz where the speed of sound in air is 343 m/s. What frequency is perceived by the occupant of a car that is traveling at 30 m/s (a) towards the factory and (b) away from the factory?

As shown in the figure, a man is traveling on a bicycle along a straight road that runs parallel to and right next to some railroad tracks. While moving at 10 m/s, he hears the whistle of a train that is behind him, as shown in the figure. The frequency emitted by the train's whistle is 820 Hz, but the frequency the man hears is 774 Hz. The speed of sound is 340 m/s. (a) What frequency is heard by a stationary observer located between the train and the bicycle? (b) What is the speed of the train, and is the train traveling away from or toward the bicycle?

A certain factory whistle can be heard up to a distance of 2.5 km. Assuming that the acoustic output of the whistle is uniform in all directions, how much acoustic power is emitted by the whistle? The threshold of human hearing is $1.0 \times 10 ^ { - 12 } \mathrm {~W} / \mathrm { m } ^ { 2 }$

A plucked guitar string produces a sound wave of frequency 0.44 kHz on a day when the speed of sound is 340 m/s. (a) What is the wavelength of the sound wave? (b) How much time elapses between the impacts of two adjacent compressions of the sound wave on your eardrum?

Two police cars have identical sirens that produce sound of frequency of 570 Hz. A stationary listener is standing between two cars. One car is parked and the other is approaching the listener and both have their sirens on. The listener measures 9.0 beats per second. Find the speed of the approaching police car. The speed of sound is 340 m/s.