Exam 16: Waves and Sound

A train moving at a constant speed is passing a stationary observer on a platform. On one of the train cars, a flute player is continually playing the note known as concert A (f = 440 Hz). After the flute has passed, the observer hears the sound with a frequency of 415 Hz. What is the speed of the train? The speed of sound in air is 343 m/s.

At a distance of 5.0 m from a point sound source, the sound intensity level is 110 dB. At what distance is the intensity level 95 dB?

Two golf carts have horns that emit sound with a frequency of 394 Hz. The golf carts are traveling toward one another, each traveling with a speed of 9.5 m/s with respect to the ground. If one of the drivers sounds her horn, what frequency does the other driver hear? The speed of sound at the golf course is 345 m/s.

Castor oil has a density of 956 kg/m³. If the speed of sound in castor oil is 1474 m/s, what is its adiabatic bulk modulus?

What is the wavelength of a wave with a speed of 9.0 m/s and a period of 0.33 s?

During a typical workday (eight hours), the average sound intensity arriving at Larry's ear is 1.8 × 10^-5 W/m². If the area of Larry's ear through which the sound passes is 2.1 × 10^-3 m², what is the total energy entering each of Larry's ears during the workday?

Two fans are watching a baseball game from different positions. One fan is located directly behind home plate, 18.3 m from the batter. The other fan is located in the centerfield bleachers, 127 m from the batter. Both fans observe the batter strike the ball at the same time (because the speed of light is about a million times faster than that of sound), but the fan behind home plate hears the sound first. What is the time difference between hearing the sound at the two locations? Use 345 m/s as the speed of sound.

Two motorcycles are traveling in opposite directions at the same speed when one of the cyclists blasts his horn, which has frequency of 544 Hz. The other cyclist hears the frequency as 522 Hz. If the speed of sound in air is 344 m/s, what is the speed of the motorcycles?

The car in the drawing is moving to the left at 35 m/s. The car's horn continuously emits a 2.20 × 102 Hz sound. The figure also shows the first two regions of compression of the emitted sound waves. The speed of sound is 343 m/s. -How far has the initial compression traveled when the second compression is emitted?

The speed of sound in fresh water at 293 K is 1482 m/s. At what temperature is the speed of sound in helium gas the same as that of fresh water at 293 K? Helium is considered a monatomic ideal gas ( $\gamma$ = 1.67 and atomic mass = 4.003 u).

A periodic wave is produced on a stretched string. Which one of the following properties is not related to the speed of the wave?

A periodic traveling wave is generated on a string of linear density 8.0 × 10-4 kg/m. Figure A shows the displacements of the particles in the string as a function of the position x along the string at t = 0 s. Figure B shows the displacement of the particle at x = 0 m as a function of time. The particle positions are measured from the left end of the string (x = 0 m) and the wave pulses move to the right. -What is the amplitude of the wave?

How far must one stand from a 5-mW point sound source if the intensity at that location is at the hearing threshold? Assume the sound waves travel to the listener without being disturbed.

A car moving at 35 m/s approaches a stationary whistle that emits a 220 Hz sound. The speed of sound is 343 m/s. What is the frequency of sound heard by the driver of the car?

A guitar string is plucked and set into vibration. The vibrating string disturbs the surrounding air, resulting in a sound wave. Which entry in the table below is correct? wave in the string sound wave in air

A periodic traveling wave is generated on a string of linear density 8.0 × 10-4 kg/m. Figure A shows the displacements of the particles in the string as a function of the position x along the string at t = 0 s. Figure B shows the displacement of the particle at x = 0 m as a function of time. The particle positions are measured from the left end of the string (x = 0 m) and the wave pulses move to the right. -What is the minimum time required for the particles to return to their respective positions at t = 0 s?

The car in the drawing is moving to the left at 35 m/s. The car's horn continuously emits a 2.20 × 102 Hz sound. The figure also shows the first two regions of compression of the emitted sound waves. The speed of sound is 343 m/s. -How far does the car move in one period of the sound emitted from the horn?

A bell emits sound energy uniformly in all directions at a rate of 4.00 × 10^-3 W. What is the intensity of the wave 100.0 m from the bell?

The diagram shows the various positions of a child in motion on a swing. Somewhere in front of the child a stationary whistle is blowing. -At which position(s) will the child hear the same frequency as that heard by a stationary observer standing next to the whistle?

Two canoes are 10 m apart on a lake. Each bobs up and down with a period of 8.0 seconds. When one canoe is at its highest point, the other canoe is at its lowest point. Both canoes are always within a single cycle of the waves. Determine the speed of the waves.