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Sound & Hearing

Distance between two seats the tone of a horn cannot be heard

A row of seats is parallel to a stage at a distance of 8.7 m from it. At the center and front of the stage is a diffraction horn loudspeaker. This speaker sends out its sound through an opening that is like a small doorway with a width D of 7.5 cm. The speaker is playing a tone that has a frequency of 1.0 × 104 Hz. The speed

Superposition of sound waves

Two speakers are driven by the same oscillator whose frequency is f. They are located a distance d from each other on a vertical pole. A man walks straight toward the lower speaker in a direction perpendicular to the pole, as shown in Figure P14.10. (Note the answers must be in all variables) (a) How many times will he hea

Sound intensity, Speed of waves on the string

1. The intensity of sound 20 meters from a race car is 0.0100 W/m^2. (A) What is the sound intensity level in dB? (B) What would the intensity (in W/m^2) be at a distance 80 m from the car? Find the corresponding intensity level in dB. 2. Suppose a violin player touches the "A" string 1/3 of the distance from the end, which

The Beat Heard by a Bat

(See attached file for full problem description) --- The Beat Heard by a Bat A bat flies toward a wall, emitting a steady sound with a frequency of 25.0 . This bat hears its own sound plus the sound reflected by the wall. Part A How fast should the bat fly, , to hear a beat frequency of 220 ? Take the speed of soun

Harmonics of a Piano

(See attached file for full problem description with proper symbols and diagram) --- Harmonics of a Piano Wire A piano tuner stretches a steel piano wire with a tension of 800 N. The steel wire has a length of 0.400 m and a mass of 3.00 g. Part A: What is the frequency f1 of the string's fundamental mode of vibration?

Standing Waves

(See attached file for full problem description and figures) --- 21.8 The figure shows a standing wave oscillating at 100 Hz on a string. Part A : What is the wave speed? 21.5 A 40-cm-long tube has a 40-cm-long insert that can be pulled in and out. A vibrating tuning fork is held next to the tube. As the ins

Calculating frequency based on velocity and sound frequency

Taking right to be positive, if a speaker is moving at a velocity of -22 m/s while emitting a sound of frequency 1385 Hz, what frequency will you hear? If the situation is reversed in the above problem and you are the one that is moving, what would be the answer? (Remember right is positive.) See attached file for full pr

Speed of Sound in Salt Water

A fishing boat is drifting just above a school of tuna on a foggy day. Without warning, an engine backfire occurs on another boat 1.40 km away. How much time elapses between the instant when the backfire is heard by the fish?

Ocean Depth

A sailor strikes the side of his ship just below the surface of the sea. He hears the echo of the wave reflected from the ocean floor directly 3.85 s later. How deep is the ocean at this point?

How Sound Travels and Pitch is Received

When a fast moving, pitched sound such as a siren travels towards and past me its perceived pitch changes. Can you please explain what this is commonly known as and why this phenomenon occurs?

Pressure Waves

A hollow log, open at one end, is struck with a stout stick. The hollow cavity of the log is 6 meters long, and the pressure waves that constitute sound travel at 342m/s. What are the frequencies of the resulting first four harmonics?

Sound source is moving toward a microphone: Pulses

A sound source is moving toward a microphone at 25 m/s, emitting sound at a constant frequency of 740 Hz (i.e. 740 pulses per second). If the source starts out 5 meters from the microphone then: -how many pulses are emitted as the source approaches the microphone? -how long is it between the instant the microphone receives

Sound Waves

A steel guitar string has a length of 74 cm and thickness of 0.37 mm. It is under 35N tension. Calculate the wave speed in the string. The density of steel rho=7.84 x 10^3 kg/m^3.

Calculating the Frequency of Sound

A train is approaching a station and blows its horn with a frequency of 200hz. If the train has a speed of 25 m/s and the speed of sound is 350 m/s, what is the frequency of sound heard by the people standing on the platform a. 190hz b. 186hz c. 210 hz d. 200hz

Wavelength Along a Cord

A cord is 20cm long, four complete waves fit along its length when vibrated 30 times per second for the waves on the cord. What is the wavelength? What is the frequency? What is the speed?

How far is the speaker from each observer?

A loudspeaker is placed between two observers who are 120m apart along the line connecting them. If one observer records a sound level of 60dB and the other records a sound level of 90dB, how far is the speaker from each observer?

Sound Wave Frequency of Strings

A piano tuner hears one beat every 2.0s when trying to adjust two strings, one of which is sounding 440Hz. how far off in frequency is the other string?

Linear superposition, interference

(a) calculate the wavelengths in air at 20°C for sounds in the maximum range of human hearing, 20 Hz to 20,000 Hz. (b) what is the wavelength of a 10-MHz ultrasonic wave?

Linear superposition, interference

A hiker determines the length of a lake by listening for the echo of her shout reflected by a cliff at the far end of the lake. She hears the echo 1.5 s after shouting. Estimate the length of the lake.

Waves: Types and Speed

Question: A rope of mass 0.65 kg is stretched between two supports that are 30 m apart. If the tension in the rope is 120 N, how long will it take a pulse to travel from one support to the other? I am having trouble understanding this above question. Can you please explain this in a simple, non-confusing way.

Tuning Fork and Its Vibrations

If the handle of a tuning fork is held solidly against a table, the sound from the tuning fork becomes louder. Why? How will this affect the length of time the fork keeps vibrating? Please explain. This is a CONCEPTUAL question.

Calculating the frequency of a string.

When a guitar string is sounded along with a 440 Hz tuning fork, a beat frequency of 5Hz is heard. When the same string is sounded along with a 436 Hz tuning fork, the beat frequency is 9 Hz. What is the frequency of the string?