Exam 16: Sound

You stand on the curb waiting to cross the street.Suddenly you hear the sound of a horn from a car approaching you with a constant speed.You hear a frequency of 90 Hz.After the car passes you by,you hear a frequency of 75 Hz.What speed was the car traveling?

If you need to build an organ whose fundamental frequencies cover the frequency range of a piano,from A1 (55 Hz)to C7 (3951 Hz),what is the smallest range of pipe lengths that you need to use? The speed of sound is 343 m/s.

A guitarist tunes a string such that it is exactly in tune with a second string of equal linear mass density and length.Both vibrate with a fundamental frequency of 110.0Hz.He decreases the tension in one string so that he hears beats of 4.6Hz.What is the ratio of the tension of the first string to that of the second?

Two people are talking at a distance of 2.0 m from where you are and you measure the sound intensity as 1.5 * 10^-7 W/m².Another student is 8.0 m away from the talkers.What sound intensity does the other student measure?

The intensity of sound decreases by a factor of ten as it pass through a wall of uniform composition.If the wall is replace with a similar wall having the same thickness,but an absorption coefficient double that if the first wall,the intensity of the same sound will decrease by a factor of ____ as it passes through the new wall.

Two identical closed-open pipes each have a fundamental frequency of 500 Hz.What percent change in the length of one of the tubes will cause a beat frequency of 10 Hz when they are sounded simultaneously?

You drop a stone down a well that is 15.0 m deep.How long after releasing the stone do you hear the splash? The speed of sound in air is 343 m/s.

The speed of sound in air is 319 m/s.What is the temperature of the air?

You are traveling slightly over the speed limit when you see a police car behind you in your rear view mirror.He immediately changes lanes and passes you by.You are so nervous after the police car passes you that you pull off to the side of the road and stop.Now you hear a siren,this time from an ambulance approaching from behind.The frequency you hear its siren is 1280 Hz.Once it passes,its frequency is 1080 Hz.What is the speed of the ambulance?

As a football player runs towards the band sitting behind the end zone,a horn player plays a note with frequency f.The frequency, $f'$ ,that the football player hears is

An explosion is detected 100 m away from ground-zero,where the intensity is recorded to be 10⁹ W/m².About 5 s later,the sound wave is recorded 1.5 km away from ground-zero.What will its intensity by at that distance? (We ignore absorption losses in this calculation!)

The speed of sound at 0 ^$\circ$ C is 331 m/s.At another temperature,the speed of sound is measured to be 343 m/s.What is this temperature?

While standing on a sidewalk,you notice that you are halfway between a clock tower and a large building.When the clock bell strikes the hour,you hear an echo of the bell 0.33 s after hearing it directly from the clock tower.How far apart are the clock tower and the building?

A standing wave in a column of air with both ends open has a frequency of 520 Hz.The next higher harmonic has a frequency of 780 Hz.How long is the column of air?

While standing at the roadside waiting for your ride you hear a frequency of 540 Hz from the siren of an approaching ambulance.After the ambulance passes,the observed frequency of the siren drops to 450 Hz.Take the speed of sound in air 340 m/s.The speed of the ambulance is

A source travelling to the right at a speed of 10 m/s emits a sound wave at a frequency of 100 Hz.The sound wave is reflected off a reflector which is travelling to the left at a speed of 5 m/s.What is the frequency of the reflected sound wave detected by a listener back at the source?

A car horn emits a frequency of 400 Hz.A car traveling at 30.0 m/s sounds the horn as it approaches a stationary pedestrian.What frequency does the pedestrian hear? The speed of sound in air is 343 m/s.

A bat flying in complete darkness emits high frequency sound of 100 kHz to locate objects.The sound travels with a speed of 340 m/s in air.The wavelength of the sound produced by the bat is

An automobile traveling at 45 mi/h (= 20.0 m/s)blows a horn at a constant 600 Hz.What is the frequency observed by a stationary observer as the car approaches?

At a distance of 20 m from a sound source the intensity level is 60 dB.What is the intensity level (in dB)at a point 2.0 m from the source? Assume that the source radiates equally in all directions.