Quiz 13 :
Sound

How far away is a lightning bolt if it takes 20 s for the sound of the associated thunder to reach the observer?

When a sine wave is used to represent a sound wave, the crest corresponds to:

A sound wave coming from a tuba has a wavelength of 0.674 m and travels to your ears at a speed of 345 m/s. What is the frequency of the sound you hear?

A series of ocean waves, 2.5 m between crests, move past at 2.0 waves/s. Find their speed.

Consider a vibrating guitar string that makes a sound wave that moves through the air. As the string moves up and down, the air molecules that are a certain horizontal distance from the string will move:

When a sound wave moves through a medium such as air, the motion of the molecules of the medium is in what direction (with respect to the motion of the sound wave)?

Which of the following ranges corresponds to the shortest wavelengths?

The frequency separating audible waves and ultrasonic waves is considered to be 20 kHz. What wavelength in air at room temperature is associated with this frequency? (Assume the speed of sound to be 340 m/s.)

The speed of sound in air is a function of which one of the following?

The speed of sound at 0C is 331 m/s. What is the speed of sound at 32C? (0C = 273 K)

The density of a certain solid is 7.2  10³ kg/m³, and its Young's modulus is 8.0  10¹⁰ N/m². What is the speed of sound in this material?

How far away is a lightning strike if you hear the thunderclap 2.00 s after you see the lightning bolt strike? (v_sound = 340 m/s, v_light = 3  10⁸ m/s)

A sound wave in air has a frequency of 515 Hz and a wavelength of 0.68 m. What is the air temperature?

Comparing the speed of sound in liquids, gases, and solids, the speed of sound is usually lowest in _____ and highest in _____.

Material 1 has Young's modulus and density , material 2 has Young's modulus and density , and material 3 has Young's modulus and density . If and if , which material has the highest speed of sound?

Material 1 has Young's modulus and density , and material 2 has Young's modulus and density . If is 30% more than and is 30% less than , which material has the higher speed of sound and how much higher is it?

A chamber that can be filled with different gases has placed in it a source of sound that in air produces a frequency of 200 Hz and a microphone to pick up the sound for frequency analysis. First the chamber is filled with helium (speed of sound 1000 m/s at room conditions), then the helium is replaced with oxygen (speed of sound 330 m/s at room conditions), and then finally the helium is replaced with carbon dioxide (speed of sound 269 m/s at room conditions). In which gas is the highest frequency of sound found by the microphone during this experiment?

Which of the following best describes a sound level of intensity 10^-6 W/m²?

Doubling the power output from a speaker emitting a single frequency will result in what increase in loudness?

What is the intensity level of a sound with intensity of 5.0  10^11 W/m²? (I₀ = 10^12 W/m²)

What is the intensity of a sound with a measured intensity level of 84 dB? (I₀ = 10^12 W/m²)

If one-half of the members of a symphony orchestra are absent because of head colds, thus reducing the overall intensity of sound by 50%, what will be the reduction in the decibel level?

If I₀ = 10^12 W/m² is the threshold of hearing, a sound with intensity I₁ = 10^10 W/m² will give a certain decibel level. Suppose a new sound has an intensity I₂ = I₁²/I₀. What is the new decibel level?

If the intensity of a sound is increased by a factor of 1000, how is the decibel level changed? The new decibel level will be:

What is the intensity of sound from a band with a sound level of 120 dB? (I₀ = 10^12 W/m²)

In the afternoon, the decibel level of a busy freeway is 80 dB with 100 cars passing a given point every minute. Late at night, the traffic flow is only 8 cars per minute. What is the late-night decibel level?

What sound level change most nearly corresponds to a factor of three change in intensity?

Doubling the distance between sound source and a listener will change the intensity, as detected by the listener, by what factor?

If the distance between a point sound source and a dB detector is increased by a factor of 10, what will be the reduction in intensity level?

The intensity level of sound 30 m from a jet airliner is 120 dB. At what distance from the airplane will the sound intensity level be a tolerable 100 dB? (Assume spherical spreading of sound.)

A very loud train whistle has an acoustic power output of 80 W. If the sound energy spreads out spherically, what is the intensity level in dB at a distance of 100 meters from the train? (I₀ = 10^12 W/m²)

By what amount does the sound intensity decrease when the distance to the source triples?

Of the frequencies listed below, to which one is the human ear most sensitive?

A sound intensity of 70 dB is observed at a distance d from the source of sound. What sound intensity would be observed at a distance 2d from the source?

A source of sound has an intensity and when its sound level is measured at a fixed distance the value found is 70 dB. The source then has its intensity increased to and when its sound level is measured at the same distance the value found is 96 dB. What is the ratio ?

If the air temperature decreases, how does the resonant frequency in a pipe closed at one end change?

The air in a pipe resonates at 150 Hz and 750 Hz, one of these resonances being the fundamental. If the pipe is open at both ends, how many resonances are between the two given ones, and if the pipe is closed at one end, how many resonances are between the two given ones?

A phase difference of 480° corresponds to what wavelength difference?

When two sound waves are out of phase by _____, destructive interference will occur.

Two loudspeakers are placed facing each other and driven by the same source at 680 Hz. A listener is positioned between the two speakers on the line separating them, thus creating a constructive interference at the listener's ear. What minimum distance would one of the speakers be moved back away from the listener to produce destructive interference at the listener's ear? (The speed of sound = 340 m/s.)

Two loudspeakers are placed facing each other and driven by the same source at 680 Hz. A listener is positioned between the two speakers on the line separating them, thus creating a constructive interference at the listener's ear. If one of the speakers is gradually pushed toward the listener, how far must it be moved to repeat the condition of constructive interference at the listener's ear? (The speed of sound = 340 m/s.)

When I stand halfway between two speakers, with one on my left and one on my right, a musical note from the speakers gives me constructive interference. How far to my left should I move to obtain destructive interference?

A 2.00-m long organ pipe is open at one end and closed at the other. Its fundamental tone has wavelength:

What is the lowest frequency that will resonate in an organ pipe 1.00 m in length, closed at one end? The speed of sound in air is 340 m/s.

When the standing wave pattern in a pipe is NANA, the pipe has which of the following set of properties? (N stands for node, A for antinode.)

What is the next harmonic frequency over the fundamental for an organ pipe 1.50 m in length, closed at one end? The speed of sound in air is 340 m/s.

A tuning fork is sounded above an adjustable length resonating tube (one end closed), which resonates at a length of 0.250 m and again at 0.750 m. What is the frequency of the fork when the speed of sound is taken to be 340 m/s?

A tuning fork is sounded above an adjustable length resonating tube (one end closed), which resonates at a length of 0.250 m and again at 0.750 m. If the tube length were extended further, at what point will the tuning fork again create a resonance condition?

For a displacement standing wave in an air column in a pipe that is open at both ends, there must be at least:

If two adjacent frequencies of an organ pipe closed at one end are 500 Hz and 700 Hz, what is the length of the organ pipe? (v_sound = 340 m/s)

A flute behaves like a tube open at both ends. If its length is 70.0 cm, and the speed of sound is 340 m/s, what is its fundamental frequency in Hz?

The air in a tube open at both ends is sent into its fundamental resonance. One end of the tube is then closed and the air column is again set into its fundamental resonance. The resonant frequency _____ after the end is closed.

The term "timbre" refers to which of the following?

What phenomenon results from two tuning forks, side by side, emitting frequencies which differ by only a small amount?

Two vibrating tuning forks, held side by side, will create a beat frequency of what value if the individual frequencies of the two forks are 321 Hz and 326 Hz, respectively?

A vibrating guitar string emits a tone simultaneously with one from a 500-Hz tuning fork. If a beat frequency of 4 Hz results, what is the frequency of vibration of the string?

Two tuning forks sounding together result in a beat frequency of 3 Hz. If the frequency of one of the forks is 512 Hz, what is the frequency of the other?

A buzzer with frequency f₀ is thrown straight upwards. On the buzzer's trip down, what is the frequency behavior heard by an observer below?

A train station bell gives off a fundamental tone of 1000 Hz as the train approaches the station at a speed of 20.0 m/s. If the speed of sound in air is 335 m/s, what will be the apparent frequency of the bell to an observer riding the train?

You stand by the railroad tracks as a train passes by. You hear a 950-Hz frequency when the train approaches, which changes to 820 Hz as it goes away. How fast is the train moving? The speed of sound in air is 340 m/s.

A sound source of frequency 1000 Hz moves at 40.0 m/s toward a listener who is at rest. What is the apparent frequency heard by the listener? (speed of sound = 340 m/s)

A 500-Hz whistle is moved toward a listener at a speed of 10.0 m/s. At the same time, the listener moves at a speed of 20.0 m/s in a direction toward the whistle. What is the apparent frequency heard by the listener? (The speed of sound is 340 m/s.)

As a train starts from rest and then accelerates down the track, coming toward me faster and faster, the speed of the sound waves coming toward me will be:

An airplane flying with a constant speed flies from a warm air mass into a cold air mass. The Mach number (the ratio of the speed of the airplane to the speed of sound) will:

While standing at a crosswalk, you hear a frequency of 540 Hz from an approaching police car. After the police car passes, its frequency is 480 Hz. What is the speed of the police car? (speed of sound = 340 m/s)

A bat, flying at 3.00 m/s toward a wall, emits a chirp at 50.0 kHz. If the wall reflects this sound pulse, what is the frequency of the echo received by the bat? (v_sound = 340 m/s)

The Doppler shift of ultrasonic waves can measure the speed of blood in an artery. If the frequency of the stationary source is 100 kHz and the reflected sound has a Doppler shift of 300 Hz, what is the blood flow speed? (The speed of sound inside the body is 1500 m/s.)

Two cars, one in front of the other, are traveling down the highway at 25 m/s. The car behind sounds its horn, which has a frequency of 540 Hz. What is the frequency heard by the driver of the lead car? (v_sound = 340 m/s)

A plane is traveling at Mach 0.980 through air at a temperature of 0C. What is the plane's speed? (Speed of sound at 0C is 331 m/s.)