Exam 17: Waves in Two and Three Dimensions

A bat emits a sound at a frequency of 30.0 kHz as it approaches a wall.The bat detects beats such that the frequency of the echo is 900 Hz higher than the frequency the bat is emitting.The speed of sound in air is 340 m/s.The speed of the bat is closest to

(Multiple Choice)

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Question 21

A certain source of sound waves radiates uniformly in all directions.At a distance of 20 m from the source the intensity level is 51 db.What is the total acoustic power output of the source,in watts? (Note: The reference intensity I₀ is 1.0 × 10^-12 W/m².)

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Question 22

Shock waves occur when

(Multiple Choice)

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Question 23

A factory siren indicating the end of a shift has a frequency of 90.0 Hz.The speed of sound is 343 m/s. (a)What frequency is perceived by the occupant of a car traveling towards the factory at 25.0 m/s? (b)What frequency is perceived by the occupant of a car traveling away from the factory at 30.0 m/s?

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Question 24

A certain crying baby emits sound with an intensity of 8.0 × 10^-8 W/m².What is the intensity level due to a set of five such crying babies,all crying with the same intensity? You can neglect any absorption,reflection,or interference of the sound.The lowest detectable intensity is 1.0 × 10^-12 W/m².

(Multiple Choice)

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Question 25

Two harmonic sound waves reach an observer simultaneously. The observer hears the sound intensity rise and fall with a time of 0.200 s between the maximum intensity and the succeeding minimum intensity. What is the difference in frequency of the two sound waves?

(Multiple Choice)

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Question 26

Two pure tones are sounded together and a particular beat frequency is heard.What happens to the beat frequency if the frequency of one of the tones is increased?

(Multiple Choice)

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Question 27

Two in-phase loudspeakers are some distance apart.They emit sound with a frequency of 1536 Hz.You move between the speakers,along the line joining them,at a constant speed of 2.8 m/s.What beat frequency do you observe? The speed of sound in the room is 330 m/s.

(Multiple Choice)

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Question 28

At a distance of 2.00 m from a point source of sound,the intensity level is 80.0 dB.What will be the intensity level at a distance of 4.00 m from this source? The lowest detectable intensity is 1.0 × 10^-12 W/m².

(Multiple Choice)

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Question 29

A howler monkey is the loudest land animal and,under some circumstances,can be heard up to a distance of 5.0 km.Assume the acoustic output of a howler to be uniform in all directions and that the threshold of hearing is 1.0 × 10^-12 W/m².The acoustic power emitted by the howler is closest to

(Multiple Choice)

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Question 30

If the intensity level at distance d of one trombone is 70 dB,what is the intensity level of 76 identical trombones,all at distance d?

(Multiple Choice)

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Question 31

Two strings of identical material and radius are stretched with the same tension with their ends fixed,but one string is 8.0 mm longer than the other.Waves on these strings propagate at 420 m/s.The fundamental frequency of the longer string is 528 Hz.What is the beat frequency when each string is vibrating at its fundamental frequency?

(Multiple Choice)

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Question 32

A transverse wave traveling along a string transports energy at a rate r.If we want to double this rate,we could

(Multiple Choice)

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Question 33

A tiny vibrating source sends waves uniformly in all directions.An area of 3.25 cm² on a sphere of radius 2.50 m centered on the source receives energy at a rate of 4.20 J/s. (a)What is the intensity of the waves at 2.50 m from the source and at 10.0 m from the source? (b)At what rate is energy leaving the vibrating source of the waves?

(Essay)

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Question 34

As you stand by the side of the road,a car approaches you at a constant speed,sounding its horn,and you hear a frequency of 80.0 Hz.After the car goes by,you hear a frequency of 60.0 Hz.What is the speed of the car? The speed of sound in the air is 343 m/s.

(Multiple Choice)

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Question 35

A jet aircraft,in level flight at constant speed,is observed directly overhead.A sonic boom is heard 13.0 s later,at which time the line of sight to the aircraft forms a 51° angle with respect to the horizontal.The speed of sound is 325 m/s.The altitude of the aircraft is closest to

(Multiple Choice)

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Question 36

A supersonic plane passes overhead at a speed of 500 m/s. If you hear the sonic boom (shock wave)4.00 s after the plane is directly overhead,at what altitude is the plane flying? Assume the speed of sound in air is 340 m/s.

(Multiple Choice)

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Question 37

The intensity of sunlight falling on the earth is about 1.4 kW/m² (before any gets absorbed by our atmosphere).At what rate does the sun emit light energy? (The earth-sun distance = 1.5 × 10⁸ km and the earth's radius = 6.4 × 10³ km.)

(Multiple Choice)

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Question 38

The sound level at 1.0 m from a certain talking person talking is 60 dB.You are surrounded by five such people,all 1.0 m from you and all talking equally loud at the same time.The threshold of hearing is 1.0 × 10^-12 W/m².What sound level are you being exposed to? You can neglect any absorption,reflection,or interference of the sound.The threshold of hearing is 1.0 × 10^-12 W/m².

(Multiple Choice)

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Question 39

An enclosed chamber with sound absorbing walls has a 2.0 m × 1.0 m opening for an outside window.A loudspeaker is located outdoors,78 m away and facing the window.The intensity level of the sound entering the window space from the loudspeaker is 79 dB.Assume the acoustic output of the loudspeaker is uniform in all directions and that the acoustic energy incident upon the ground is completely absorbed and therefore is not reflected into the window.The threshold of hearing is 1.0 × 10^-12 W/m².The acoustic power entering through the window space is closest to

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Question 40

Showing 21 - 40 of 44

Exam 17: Waves in Two and Three Dimensions

A bat emits a sound at a frequency of 30.0 kHz as it approaches a wall.The bat detects beats such that the frequency of the echo is 900 Hz higher than the frequency the bat is emitting.The speed of sound in air is 340 m/s.The speed of the bat is closest to

A certain source of sound waves radiates uniformly in all directions.At a distance of 20 m from the source the intensity level is 51 db.What is the total acoustic power output of the source,in watts? (Note: The reference intensity I0 is 1.0 × 10-12 W/m2.)

Shock waves occur when

Two harmonic sound waves reach an observer simultaneously. The observer hears the sound intensity rise and fall with a time of 0.200 s between the maximum intensity and the succeeding minimum intensity. What is the difference in frequency of the two sound waves?

Two pure tones are sounded together and a particular beat frequency is heard.What happens to the beat frequency if the frequency of one of the tones is increased?

Two in-phase loudspeakers are some distance apart.They emit sound with a frequency of 1536 Hz.You move between the speakers,along the line joining them,at a constant speed of 2.8 m/s.What beat frequency do you observe? The speed of sound in the room is 330 m/s.

At a distance of 2.00 m from a point source of sound,the intensity level is 80.0 dB.What will be the intensity level at a distance of 4.00 m from this source? The lowest detectable intensity is 1.0 × 10-12 W/m2.

A howler monkey is the loudest land animal and,under some circumstances,can be heard up to a distance of 5.0 km.Assume the acoustic output of a howler to be uniform in all directions and that the threshold of hearing is 1.0 × 10-12 W/m2.The acoustic power emitted by the howler is closest to

If the intensity level at distance d of one trombone is 70 dB,what is the intensity level of 76 identical trombones,all at distance d?

A transverse wave traveling along a string transports energy at a rate r.If we want to double this rate,we could

As you stand by the side of the road,a car approaches you at a constant speed,sounding its horn,and you hear a frequency of 80.0 Hz.After the car goes by,you hear a frequency of 60.0 Hz.What is the speed of the car? The speed of sound in the air is 343 m/s.

A jet aircraft,in level flight at constant speed,is observed directly overhead.A sonic boom is heard 13.0 s later,at which time the line of sight to the aircraft forms a 51° angle with respect to the horizontal.The speed of sound is 325 m/s.The altitude of the aircraft is closest to

A supersonic plane passes overhead at a speed of 500 m/s. If you hear the sonic boom (shock wave)4.00 s after the plane is directly overhead,at what altitude is the plane flying? Assume the speed of sound in air is 340 m/s.

The intensity of sunlight falling on the earth is about 1.4 kW/m2 (before any gets absorbed by our atmosphere).At what rate does the sun emit light energy? (The earth-sun distance = 1.5 × 108 km and the earth's radius = 6.4 × 103 km.)

Foundations

A: Foundations

Motion in One Dimension

Acceleration

Momentum

Energy

Principle of Relativity

Interactions

Force

Work

Motion in a Plane

Motion in a Circle

Torque

Gravity

Special Relativity

Periodic Motion

Waves in One Dimension

Fluids

Entropy

Energy Transferred Thermally

Degradation of Energy

Electric Interactions

The Electric Field

Gausss Law

Work and Energy in Electrostatics

Charge Separation and Storage

Magnetic Interactions

Magnetic Fields of Charged Particles in Motion

Changing Magnetic Fields

Changing Electric Fields

Electric Circuits

Electronics

Ray Optics

Wave and Particle Optics

Filters

A certain source of sound waves radiates uniformly in all directions.At a distance of 20 m from the source the intensity level is 51 db.What is the total acoustic power output of the source,in watts? (Note: The reference intensity I₀ is 1.0 × 10^-12 W/m².)

At a distance of 2.00 m from a point source of sound,the intensity level is 80.0 dB.What will be the intensity level at a distance of 4.00 m from this source? The lowest detectable intensity is 1.0 × 10^-12 W/m².

A howler monkey is the loudest land animal and,under some circumstances,can be heard up to a distance of 5.0 km.Assume the acoustic output of a howler to be uniform in all directions and that the threshold of hearing is 1.0 × 10^-12 W/m².The acoustic power emitted by the howler is closest to

The intensity of sunlight falling on the earth is about 1.4 kW/m² (before any gets absorbed by our atmosphere).At what rate does the sun emit light energy? (The earth-sun distance = 1.5 × 10⁸ km and the earth's radius = 6.4 × 10³ km.)