Sound Definition and 1000 Threads

Hi friends, I need the average speed of sound in some common solids, such as Si, Cu and Al, over temperature ranges from 100K to 500K. After 5 hours of surveying acoustic and physical properties handbooks and googling the web, what I find is almost nothing. Does anybody know a...

Homework Statement The intensity of the sound from a certain source is measured at two points along a line from the source. The points are separated by 11.8 m, the sound level is 68.10 dB at the first point and 60.31 dB at the second point. How far is the source from the first point? d =...

I'm trying to understand relativity on a simple example: 2 objects A & B moving in exactly opposite directions at 0.6c each, starting from frame C at the center of things that remains stationary. So, we have: W <----0.6c A ...... C ..... B 0.6c----> E 1. From frame C, A is moving...

Light waves, photons; sound waves, phonons; water waves, "hydrons"? Light waves are made of photons; sound waves are made of phonons; so are water waves made of "hydrons", and if so, how would they behave, and would it be possible to make a water laser or something similar based on these particles.

When swimming underwater, why does sound from above the surface sound very faint? I know that the answer to this may be simple, but I just can't put my finger on the answer. I know that sound travels faster in water then it does in air, does this fact have anything to do with it? Thanks!

I didn't follow the template because this is more of a conceptual question that I can't get a clear answer for. I understand that sound intensity varies with 1/r^2 because the total intensity at a point in the wave is constant and if you have spherical propagation then the area of the surface...

Why is it that materials with a higher bulk modulus value allow for sound waves to propagate through them faster? A material with a high bulk modulus requires a relative greater increase in pressure to contract by the same volume as a material with a lower bulk modulus, and as such sound waves...

I don't have any specific numerical values for this, as it's a general question, but hopefully I explain it well enough using only words: If you plot a graph of position vs. flight time (of a sound pulse, for example), what is the slope of that graph going to be? (That is, what does the slope...

Homework Statement What is the wavelength of a 25 Hz sound wave? What is the wavelength of a 4.5 kHz sound wave? Homework Equations wavelength = velocity / frequency or λ = v/f The Attempt at a Solution I know that I'm supposed to plug the 25 into the equation, but he didn't give...

Hello! I am a recent university grad, majored in physics, with a strong background in programming and maths. I've had a couple non-physics research positions, and am looking to go back to school for a masters. All my life I've been very passionate about music, from composing classical...

Homework Statement Determine the speed of sound in argon gas at 30 degrees celcius. Argon is a monoatomic gas with atomic mass 40. Assume adiabatic and ideal gas conditions. The mass of a nucleuon is 1.67*10-27 kg=mp. Homework Equations Adiabatic constraint: pVγ=constant. Ideal gas...

hello, since a while my mind is caught by an idea. This idea is concerned with underwater sound massage system. For this purpose i would like to build an array of underwater sound transducers, which can all be steered individually (to do a coarse beam forming). However, since i am...

I don't recall ever trying a mystery sound competition. So, in the fashion of other competitions, whoever can name the source of the sound picks out the next mystery. The imagery in this video is irrelevant and not intended as a clue or a false lead...

Homework Statement You see a neighbour in a cottage across the lake chopping wood. He is 2 km away and you see that it takes 2 s to hear each chop after you see it happen. Calculate the air temperature. (v= 332+ 0.6 T) Homework Equations v=d/t The Attempt at a Solution v= 1 km/s...

why is sound heard more clearly in night than at day?

Like on a hot day, cars make these clicking sounds on the surface? Does having a silver or white-colored car make it worst? Because I've seen black -colored ones do that too

Okay, I have this problem worked out, but I have no clue if my answers are right. Could someone please check my work and give me some confidence or show me where I may have messed up. Homework Statement Two loudspeakers, one of them generates sound with 400 W power the other with 100 W. The...

http://arxiv.org/abs/1108.4389 Gauge Theories Labelled by Three-Manifolds Tudor Dimofte, Davide Gaiotto, Sergei Gukov (Submitted on 22 Aug 2011) We propose a dictionary between geometry of triangulated 3-manifolds and physics of three-dimensional N=2 gauge theories. Under this duality...

can we hear the sound of our steps in moon?

So, I'm writing a music A-Level dissertation, but because of my love for physics, I've based it on the physics of sound. I didn't think this should go into the homework section because it's not so much homework that I need help with. Whilst working through some fundamentals on my board, I...

when light rays fall perpendicularly on a separating surface between two media it doesn't refract according to Snell's law and it is the same with sound waves how to prove something like that mathematically?? Thanks in advance

what is the mechanism of small holes in auditorioms used as sound absorbers

Homework Statement I am writing my Extended Essay for IB, where I look at the possibility of obtaining accurate results in open system of a school, by accounting for all energy losses that occur during the investigation. Before conducting my experiments (which included an air track with two...

I am doing a module to adjust the noise in a motor such that motor inside piston stroke is touching some mechanical part leads to small noise. I would like to adjust these by using sound sensoror presser or vibration sensors. I don't know which one to use in that sistuation but my guess is sound...

1-why does sound intensity increase at night? 2-what makes diffraction of sound more observable than diffraction of light? 3-reflection of sound takes place when it falls on a reflecting surface whatever the distance between the vibrating source and the surface but in case of echo there are...

ive got two basic questions. 1: Does density effect viscosity, as in is it possible to have a highly dense but low viscosity fluid and vice versa. 2: I know in space there's no sound but can you hear your own heartbeat and other internal vibrations?

Homework Statement A student holds a 325.6 Hz tuning fork near the end of a pipe that is closed at one end. He notices that resonances can be heard for several different lengths, one of which is 55.5 cm. He gradually lengthens the pipe to 92.5 cm where he detects the next resonance...

Homework Statement Henry and Tom see a flash of lightning and then hear the resulting clap of thunder. Henry measures the sound level of the thunder as 65 dB while Tom, who is 800 m further from the event, measures it as 63 dB. Homework Equations The Attempt at a Solution I_H /...

According to the equation c=√(C/ρ) where c is the speed of sound, C is the coefficient of stiffness and ρ is the density of the medium throughout which a sound is played the speed of sound should acctually decrease with an increase in density. Why is this so? I would've thought that increasing...

3rd Semester Schedule Introduction to Differential Geometry Introduction to Real Analysis - using Rudin Advanced Linear Algebra Symbolic Logic (philosophy course) Intro Programming (Java) I have some experience with proofs in LA, read up on basic techniques of proof over summer...

Postulate a parcel of air that is transmitting sound waves. Can that parcel ever be considered to be in a state of equilibrium? I maintain that it cannot. How say you?

So I was wondering how to create a sound activated LED circuit for each of my speakers. I want the red LEDs to light up when the subwoofer is activated and the blue LEDs to light up when the left and right floor speakers are activated. I had a thought about wiring the LEDs parellel to in input...

Sound Intensity-- just need someone to check my work :) Homework Statement While enjoyable, rock concerts can damage people's hearing. In the front row at a rock concert, 5m from the speaker system, the sound intensity is 145 dB. How far back would you have to sit for the sound intensity...

Greeting Physics Forums; my first post here. Thanks in advance for your time! Approximately how many soundwaves compose what we can say is a single noise, like a drumbeat? I know there are multiple frequencies involved and our brain interprets this in it's own way. There is interference...

Is there anything that focuses sound like is done with a lazer? That is where you wouldn't be able to hear anything unless you were in the beam path and maybe the intensity would be magnified.

Homework Statement A sound wave with frequency 2 MHz is propagating through water and hits a ship hull made out of steel. The effective value (RMS?) of the acoustic pressure in water is 1kPa = P0w. The acoustic impedance Zw for water is 1.46*106 and for steel Zs it is 4.03*107. The wave...

Homework Statement Find the sound intensity level of a thunder bolt, if a person is standing 200 m from the spot it hits. The bolt hits the ground vertically and the height of the bolt is 1500 m. The bolt has an electrical current of 20 kA and a voltage of 30 MV. It discharges thrice, each...

I noticed that in water, sound travels faster than in air, but when light hits water, its velocity decreases. Is this because sound is a longitudinal wave and light is a transverse (electromagnetic) wave??

Hi, I'm sure the question is quite naive but I'm having a hard time getting around the fact that the sound of a symphony orchestra can be emitted from a speaker. That a large collection of sounds of vastly different tonality, playing simultaneously, can be reproduced by a single sound source...

I'm trying to wrap my head around shock waves produced by bullets and their properties. In particular I'm interested in what affects the duration of the shock wave in time. Say someone shoots at me, the bullet passes near me, and I hear the shock wave produced by the bullet. If you look...

Hello everybody, I'd really like to be able to explain what I hear in terms of wavelengths. My question could be split into a few, but I will try to focus on the main issue so it's more simple to answer. Situations in real life: It comes to my mind when I'm in live shows, the loud ones...

Hello all, I come from musical sciences, but I'm trying to learn something about acoustics, so here I am, asking for some help about the impedance tube sound absorption coefficient test. I have and impedance tube, two microphones technique (ISO 10534-2), B&K microphones connected to the...

Ok after searching google through and through I have decided this is the closest related place I could ask about my situation that I could find. After this happening Friday morning I have been unable to stop thinking about it and would like to hear someone else's views. On this past Friday...

I'm not sure whether to put this in Earth or Astrophysics. How far would these sound vibrations/waves travel? Do they just stay within the Earth, or is it possible for them to travel through space; and if so, how or why or is it possible for these vibrations to attract asteroids?

http://www.ted.com/talks/honor_harger_a_history_of_the_universe_in_sound.html?utm_source=newsletter_weekly_2011-06-29&utm_campaign=newsletter_weekly&utm_medium=email" Honor Harger http://www.ted.com/talks/janna_levin_the_sound_the_universe_makes.html" Janna Levin Ringing of space... then...

Hi. I apologize if this thread is in the wrong location, as you see: My knowladge of Physics is (probably) at the level of a 10th grader... or maybe less... which is what I am. I won't bore you with how I got into such a theory, but before I start I'd like to state that I start this topic for...

I plan on adding a 5th class to my semester (which is already quite packed), however I was wondering if this sounded like the Thermodynamics class that everyone on PF always complains about: "ENGR 251 Thermodynamics I (3 credits) Prerequisite: MATH 203 (Cegep Mathematics 103 [Calculus 1])...

While studying the Doppler effect at school, it struck me as strange that the following two problems have different solutions: a) you are moving at 40 m/s toward a source that is making a sound with a frequency of 1000 Hz. What frequency do you hear? (speed of sound= 340 m/s) b) The...

I made a youtube video explaining it. I fell on my elbow and now I am almost without pain, but this sound makes me nervous. The sound is a nonevent for my doctor, but for me it is. Can someone help? Had someone the same thing? thx

Homework Statement [PLAIN]http://www.antonine-education.co.uk/Physics%20A%20level/Options/Module_8/Topic_6/cars_4.gif What is the speed of sound, relative to: A - B - C - Homework Equations None. The Attempt at a Solution For B, since B is a stationary reference point...