Sound Definition and 1000 Threads

Homework Statement The rod of length l and mass m_0 is hinged on two same wires (Fig. 3 on second page - example ,,4. Zvučící dráty" - http://fyzikalniolympiada.cz/archiv/55/fo55a1_z.pdf). With this load, each of the wires gives basic tone height c in natural tuning, f_c = 264 Hz. A) Move the...

I have a question. I was wondering if it was possible to put a vibrational sound frequency to a photon? Another way of putting it, is it possible to pump sound into a laser beam and give the photon a vibrational frequency consistent with the sound added? Thanks.

I'm doing some MCAT practice, and one question asks: A submarine sends a sonar signal in a direction directly downward. It takes 2.3 seconds for the sound wave to travel from the submarine to the ocean bottom and back to the submarine. How high up from the ocean floor is the submarine? (The...

Why is it that the maximum sound coming from a Rijke tube happens only when heated wire gauze is placed at 1/4th the length of the tube from the bottom. According to Rayleighs criterion(copy pasted) "If heat be periodically communicated to, and abstracted from, a mass of air vibrating in a...

If I have a sphere with radius r, a distance d away from a sound source of intensity I0. What will the intensity I of the sound wave be on the point of the sphere directly opposite the source? Preferably I would like to find the intensity of the wave at any point on the sphere.

Hi The speed of sound in a fluid is defined as c_s^2 = \frac{\partial P}{\partial \rho} where P is the pressure and ρ the density. In my thermodynamics-course this was how we defined the speed of sound in an ideal gas, I have never read the explanation anywhere for, why this relation is also...

Hi there , I have two cast iron crankshafts for an engine I'm building , now even though they are similar in every way , made ofr the same engine etc etc, there is one thing I noticed different and it got my attention , I took a stainless steel screwdriver and hit each one of the cranks at...

Homework Statement An alarm clock makes a sound that has intensity 60 dB at a distance of 1 m. What is the sound intensity of 100 such clocks which are all 100m away? (A) 0.6 dB (B) 40 dB (C) 50 dB (D) 60 dB Homework Equations I1/I2 = R2^2/R1^2 The Attempt at a Solution If...

Homework Statement At 1 m away from the source of a sound, the intensity of the sound is 90 dB. At 10 m away the intensity is…? The answer is 70 dB but I don't know how... Homework Equations I = Power/Area The Attempt at a Solution My thought was to set up the equations...

Homework Statement Two train whistles have frequencies of 180 Hz in air (v = 344 m/s). When one train is at rest sounding its whistle, a beat frequency of 2 Hz is heard from the moving train which is sounding its whistle as well. What is the moving train's speed if it is approaching the...

Homework Statement A clarinet behaves as an air column that is open at one end. For a particular fingering, the length of this air column is 24.6 cm. At 20°C, this fingering sounds the pitch "F" which is 349.2 Hz. During a concert, the breath of the musician raises the bore temperature to...

Homework Statement A source of sound emits waves at a frequency f 450 Hz. An observer is located at a distance d 150 m from the source. If the observer is moving away from the source at a velocity vobs 40 m/s, how does the number of wavefronts change with time? dN/dt ? (in Hz)...

Homework Statement When near an object, a bat decreases the duration of its chirps and the time interval between chirps. If the chirps last 3 x 10-4 s, what is the minimum distance for an object at which the first part of the echo overlaps the ending of the chirp? Note: the speed of sound...

http://imageshack.com/a/img841/50/qgx3.png The above diagram shows the analyzer of waveform taken from a song. I wanted to know in terms of acoustics how is it that the different frequencies are produced at the same time by the same source. I know about interference but don't know how it...

i had always belived that sound wave was a longitudinal wave till i come across something saying that its a transverse wave in solid.can anyone explain is it so??

Homework Statement One wheel goes at 850 rpm and the other at 780 rpm, and obviously they make a noise. Standing in an enclosed room, you hear the sound intensity increase and then decrease periodically due to wave interference. How long does it take between successive times for the sound...

Why does water attenuate sound waves more than air? Is it because of it's bulk modulus? This is what I understand. Speed through a medium is determined by the elastic component over the inertial component. Since water has a much greater bulk modulus (elastic component) than air, it makes the...

Hello, I have two question regrading sound waves. The first one: The pressure P(x;t) at a point x at time t in a medium through which a harmonic wave is travelling can be described by: P(x,t) = Asin(wt -kx) If the equation describes a pressure wave traveling in air, with amplitude 2 Pa and...

Homework Statement Two loudspeakers A and B of equal power are separated by a distance of 1.4 m. Both the speakers emit sound waves in phase and of frequency 450 Hz. If a microphone were to be moved from A in a direction perpendicular to AB, at what distances from A will it detect a minimum...

I did an experiment for school, and I put a speaker in a styrofoam box with a rectangle cut out of the front. I had styrofoam bricks that fit perfectly in the hole, each with a hole cut out. The hole shape differed, with things like a funnel, a diagonal line, a circle, a square, etc. I was...

Sound "Factor of" Homework Statement The intensity level of a particular sound coming through a medium gets reduced from 80 dB to 41 dB. By what factor is the acoustic power that can pass through changed by? B1=80 B2=41 Homework Equations 10*log(\frac{I2}{I1}) = B1-B2 The...

Dear all, I have encountered an issue in understanding how microphone works and I hope you guys can assist. There are two scenarios involved. In the first scenario, there is tuning fork and a microphone. The microphone contains a small disc attached to a magnet and a fixed coil. (Please...

Homework Statement If you drop a stone into a deep well and hear a splash 4.68s after dropping the stone, how far down is the water level? Neglect air resistance and assume that the speed of the sound in air is 3.40x10^2 m/s Homework Equations v=d/t d=v1t+1/2at^2 The Attempt at a Solution Here...

This may be fairly straightforward but it is a concept that I am really having problems understanding. A sound wave is a pressure disturbance that travels through a medium by means of particle to particle interaction, so why is the wave velocity so much faster than the velocity of the particles...

whistle -- How does a a whistle produce sound? How does a a whistle produce sound? And what makes galton or dog whistle to produce high frequencies ...?

Not sure where to post it, but perhaps EE will be OK. I have problems recording sound on my computer, and I have these problems for as long as I remember - using several microphones and several computers in the last 20 years. I always thought reasonable quality mic and reasonable quality...

Homework Statement Two sources, A and B, emit a sound of a certain wavelength. The sound emitted from both sources is detected at a point away from the sources. The sound from souce A is a distance d from the observation point, whereas the sound from source B has to travel a distance of...

Homework Statement The density of a sample of air is 1.211 kg/m3, and the bulk modulus is 1.42 · 105 N/m2. a) Find the speed of sound in the air sample. b)Find the temperature of the air sample. Give answer in °C. Homework Equations The Attempt at a Solution I found...

can sound travel from a body of water to air? if so, what might it look like?

Homework Statement Using the apparatus that I've drawn, I have to deteremine the % composition H2O2 in an unknown solution. 2. Relevant information H2O2 (aq) -enzyme-> H2O(l) + O2(g) or 2H2O2 -Enzyme-> 2H2O(l) + O2(g) when balanced The test tube (1) contains H2O2 solution with an...

Hello, I'm having a bit of a problem with the following problem: A supersonic airplane flying at the velocity v is flying horizontally to the ground with altitude h. At the exact moment when the plane is vertically above a listener on the ground, it emits a sound. It takes Δt seconds for the...

Both source and observer are at rest. If the wind blows from source to observer will the wind affect the wavelength of sound??

You are climbing in the High Sierra where you suddenly find yourself at the edge of a fog-shrouded cliff. To find the height of this cliff, you drop a rock from the top and 8.50s later hear the sound of it hitting the ground at the foot of the cliff. Ignoring air resistance, how high is the...

Homework Statement A fly is moving with a speed vl=3m/s and a bat is chasing it with vs=5m/s. The bat is emitting a sound with fs=50kHz. They are moving on the same line towards point C which is a source emitting a sound at f'=57Hz. Find the frequency of the total sound the fly is hearing. The...

Hello everyone :smile:, after spending many hours watching youtube videos, reading wikipedia articles and other related material, I came to the conclusion that my best hope at understanding this is to have an explanation personally explained to me, and I trust this is the right place to ask for...

Hello physicsforums. What causes noise in electrical cables and/or transformers and/or electrical stations ? By noise I mean mechanical sound waves like bzzzzzzzz, not signal noise. And what is the proper way to search in google for this, I could not find a wikipedia article on this.

i am interested in learning about sound .so please can anybody provide a website for learning about it .

Frequency is pitch. Or how fast it oscillates. So what does the amplitude translate to in physical space? I know its volume, or the amount of energy. But what does it actually do to the air when you increase the amplitude?

Hello Everyone, I have a somewhat simple question: Why do we hear a sound better when we're closer to the object making it?Or less when we're farther? (ie a car siren is disturbingly loud when standing next to the engine but not the same when standing like 10 feet away). Could it be because...

I think they(longitudinal waves)hits the air,but they are not reflected back because air is very light.In the same way,when they hit a wall,as the wall is not going to vibrate vigorously,Some of the waves are absorbed(i.e. they make the wall vibrate)and the others are reflected back. If I am...

Is there any possibility to converting sound energy to electrical energy by using piezo electric material.

They talk about light's unique dual nature, that it can be both a wave and a particle (photon). One illustration for that is the following experiment, a single photon can go through one hole, and leave a particle like mark, or it can go through two holes, and leave interference marks...

does density affect sound velocity ? i know sound velocity is dependent on inertial and elastic properties but does it depend on density ? or just molecular mass ? if two objects having the same atomic mass , but one has higher density than the other due to the difference in bonding...

If the velocity of air flow through a grill is halved but the area of the grill is doubled, By what factor will the sound power be reduced? air flow through a grill represents a dipole sound source, so it depends on the 6th power of velocity, but how does it depend on the area? If I take sound...

Here's a question I got on an exam: During a typical workday (eight hours), the average sound intensity arriving at Larry's ear is 1.8 x 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...

Good afternoon all My question is, when we observe stationary waves, and we know that at a certain point, the sound is maximum, is this the displacement node or the displacement antinode? I have read a few different sources and currently i have encountered both. To me it makes more sense...

What is the equation to find relative sound intensity from a source when given the angle?

Hello. Homework Statement A person holds a rifle horizontally and fires at a target. The bullet has a muzzle speed of 20 m/s and the person hears the bullet strike the target 1.00s after firing it. The air temperature is 72 degrees F. What is the distance to the target? Homework...

Hi all! I am searching of types of microphone/disc that can detect wheezing sound from the chest area but I am totally clueless of what type of microphones to use. Also, there should be less noise when picking up the signal. Currently I am using a piezo disc, but that could not detect the...

(A question from The Berkeley Review MCAT prep book. The book gives the answer in the form of the equation below. I'm still having trouble figuring out how an example of this would look in real life. If someone would provide a hypothetical narrative where the following could take place, that...