Sound Definition and 1000 Threads

Homework Statement Two identical loudspeakers are driven in phase by the same amplifier at a frequency of 680 Hz. The speakers are 4.6 m apart. An observer stands 9 m away from one of the speakers as shown. The observer then starts moving directly towards the closest speaker. How far does the...

Homework Statement Homework Equations v = d/t Solve for t. t = d/v The Attempt at a Solution In my General Physics 2 course we are doing sound waves I have the answer to the problem which is 90.8m I am trying to understand the concepts of sound wave. So please correct me if I am wrong, 1...

Homework Statement This is just a question about a question in Serway & Jewett's "Physics for Scientists and Engineers 3rd Ed". It's Objective Question 3 from Chapter 18, building on Example 18.1 from the text. Two identical loudspeakers placed 3.00 m apart are driven by the same oscillator...

Homework Statement .[/B] For a certain type of steel, stress is always proportional to strain with Young's modulus 20 x 10^10 N/m^2. The steel has density 7.86 x 10^3 kg/m^3. A rod 80.0 cm long, made of this steel, is fired at 12.0 m/s straight at a very hard wall. a) The speed of a...

Homework Statement Two in-phase loudspeakers, which emit sound in all directions, are sitting side by side. One of them is moved sideways by 3.0 m, then forward by 4.0 m. Afterward, constructive interference is observed 1/4 and 3/4 of the distance between the speakers along the line that joins...

Homework Statement Sorry, it's not an actual problem, it's just a statement I don't understand from my text - "The density of water vapor is less than that of dry air. Therefore, the higher the humidity (that is, the more water vapor there is in the air), the lower the density of the air. For...

Hi, there is no particular question that I need help on, just something my lecturer told us in lesson which I couldn't quite understand so i'd like to check my understanding on this. I know that the speed of a soundwave is 'c' in undisturbed flow. Suppose the flow velocity is 'U'. If the...

Let's say you have an impulse of noise, eg. via a guitar string, or a resonant bandpass filter, and it decays naturally. If "1" is the maximum initial amplitude of sound, and "0" is no sound at all, what is the equation for decay of sound over time (x)? Is it: y = 1/c^x Or y = 1/(x+1)^c I...

I'm wondering if the sound of two identical horns positioned perfectly in front of each other and emitting the same sounds/pressure will cancel each other out no matter what where the only variable changing is how far apart the horns are from each other. Maybe an example would be two clarinets...

I have a graph measuring 1/3 octave sounds checking if they fall into a range so they are within a defined tolerance. If for example, I have 20 specific 1/3 octave frequencies I am looking at, I can figure out a percentage of which of the 20 frequencies fall in tolerance fairly easily...

How and why do we hear through the brick walls? Does the sound actually penetrate the walls?

Just like a concave mirror concentrates light, it can also concentrate sound waves. Ray diagrams like the following look as if all waves converge to a single point of INFINITE power density which of course is not true, probably because of the wave nature of light or sound. What is the correct...

If a sound wave hits multiple scatterers spaced closer than the wavelength and moving fast but at different velocities how is the reflective beam is affected?

Hello Forum, A sound wave intensity (pure frequency) is proportional to the square of the wave pressure amplitude, i.e. ##I \approx p_0^2##, where ##p_0## is the pressure wave amplitude: ##p_0 sin(\omega t \pm kx)##. This means that the (gauge) pressure value goes larger (positive) and lower...

I would like to be able to triangulate a sound's location based on the inputs of two robotic sensors. I know this involves trigonometry, but I am a little out of practice. I think the practice of triangulation also is useful for radio signals. I would like to create a triangulation algorithm...

Elsewhere there are discussions about the feasibility of killing bugs with ultrasound. All of those discussions consider a situation, presumably, where the bugs are in the air. That seems a tricky problem, but perhaps not the one I wish to discuss. The Problem: So in California we have this...

Homework Statement Stated in the attached file. Homework Equations Wavelength = 2 times length divided by harmonic I don’t know if it’s the relevant equation The Attempt at a Solution I used the equation I wrote. So, if the left side is 10cm longer, I guess it might be 2(10).

I have seen few examples on Doppler effect and i am confused about one such. We are standing on ground. If the source of sound S moves and Object O is stationary. We would presume the frequency as well as wavelength of sound be changed to the obeject O. But if O moves towards or away from S...

Hi everyone, Apologies for what may be a relatively obvious question for you but I'm struggling to understand a concept that was discussed in my introductory Physics class. I would really appreciate any help you could offer. During an explanation of sound, we were told today that a sharp sound...

The speed of sound is 761.2 mph, or, according to my math, 1116.5 fps. If you are 8 ft away from the source, how long does the sound take to reach you? What is the formula for doing this? I divided 8 into 1116.5, and got 139.5 - but that doesn't seem to tell me anything. Obviously, the answer...

Is the speed of sound different through the same piece of metal when it is heated compared to when at ambient temperature?

I try to understand the following graphics with x-axis being the radius of a typical star : I would like to knwo if ##\delta c/c## (y-axis) represents the relative error between theoretical and experimental values or if it represents the fluctuations of speed of sound inside. If these are...

I have some skepticism. All it says is "enhances molecular interaction", which sounds kind of vague to me. They also say it "shapes" the favor. None of which make sense. So either I don't understand how its possible (which is possible) or its some nonsense... which is also possible. Anyways, I...

Homework Statement The sound source of a ship’s sonar system operates at a frequency of 18.0 kHz. The speed of sound in water (assumed to be at a uniform 20°C) is 1482 m/s. What is the difference in frequency between the directly radiated waves and the waves reflected from a whale traveling...

If air is made up real little particles, then why would the waves made up of these particles not bounce off? Here's my attempt at an explanation for the principle of superposition for soundwaves. The wave is transferred by the air molecules hitting the ones adjacent to it. But because air is...

Suppose you have a glass of water, and you beat a spoon on the bottom layer of glass through the mouth of glass, repeated beatings in a regular fashion will cause in increased frequency of sound produced due to the spoon beating?What causes such increase in frequency?

Greetings! I was asked to provide an introduction: I am a retired Professor, in Music of all fields! I come from a family of engineers. I have long been researching sound and it's relationship with magnetic frequencies. I am also engaged in the development of a battery using permanent magnets.

I saw on a web page a video of tiny Agnes Scott College vs Princeton University from 1966 on GE College Bowl.Agnes Scott won (!), but one of the questions that both schools got wrong was asked by the moderator: The speed of sound in air is about 1,100 feet/sec. The speed of sound in steel is...

Hey guys, I’m a junior in Florida studying mechanical engineering. My school currently offers a 4+1 accelerated masters program for mechanical engineering which I’m strongly considering. How feasible is it for me to to do this and then apply for a PhD in electrical engineering to another...

Hi, I have heard much about this, but I'm not an expert. Now I know that mosquito hears by Johnston's organ at antennas. Also that mosquitoes have something like "sound/frequency filter", it means they listen to only some sound/frequency, especially other mosquitoes or other animals. Is it...

I was just wondering (Wondering!? Stop wasting our precious time!) about clapping my hands. *Claps* It's sound energy. A little energy is released as heat. Good. This means that I have used some energy from my body. In making those two energies. Right. <<Mentor note: rant removed>> So, I am in a...

Greg Bernhardt submitted a new PF Insights post Direct Echo-Based Measurement of the Speed of Sound Continue reading the Original PF Insights Post.

A star is kind of a huge nuclear explosion. Things are smashing into each other all the time, bouncing off, and all this movement creates vibrations, so there's actually sound sound inside any star. Pulsars have produced radio waves, which have been converted into audible sound waves, thus...

Imagine a car which has a speaker attached to the back. Speaker is blasting very high volume music towards the reverse direction of the car. Now the car starts accelerating and in a few seconds starts moving faster than the speed of sound. Will a listener be able to hear the sound now. Will...

I measure sound (dB) from a speaker at 0cm and 100cm using a diaphragm microphone. 0cm-100dB, 100cm-30dB diaphragm microphone cinsists of a diaphram, coil and a permanent magnet. the coil is attached to the diaphragm, when a sound wave hits the diaphragm it causes to move back and forth which...

Hello everybody. I am involved in a project aiming to address Physics Misconceptions regarding Sound through the creation of virtual musical instruments. One of the major student misconceptions I have found in bibliography is the fact that students perceive sound pitch and loudness as being the...

If a pulse of light, which has momentum p = E/c, interacts with particles of air, would it not change their momentum over time, causing mechanical energy (sound)? As I understand it, sound is mechanical energy moving through particles as they vibrate. Why can't the momentum of a pulse of light...

Hello, I am on the search for papers, books, etc. on how one can measure the viscosity of viscous materials via the speed of sound. I've searched for a while now and haven't been able to find much on this topic. Any help is greatly appreciated.

Homework Statement Find the sound intensity of a thunderbolt 1 km away. What sound intensity (dB) is it 1 km away? The thunderbolt can be heard up to 20 km away. The sound is spherical. The air absorbs nothing. Homework Equations L = 10 \cdot lg(\frac{I_1}{I_0}) \Delta L = 10 \cdot...

Suppose we have an ultrasonic transmitter and an ultrasonic receiver, separated by some fixed distance ##d##. Both devices are attached to an oscilloscope. The transmitter generates ultrasonic waves at some frequency ##f## that we can change. The receiver is some piezoelectric that translates...

Hello, Wikipedia gave me prior hints as to how the speed of sound depends on viscosity but after searching on Google scholar and Google, I have yet to find any direct equations/findings that give a direct relationship of the speed of sound to the visocisty of fluids and solids outside of...

Note: I'm sorry if I have to use the template, but I already have the solution, I just do not understand it and need help understanding it. 1. Question: A firework explodes at a 40 metre height and gives off a bang which measures at 100 dB at ground level. What is the power of the sound that...

Homework Statement The fundamental frequency of a violin string is 283 Hz. Calculate the frequency of the 2nd harmonic. Known: f = 283 Hz Homework Equations v = fλ f(n) = n*v/2L λ= L v(sound) = 343 m/s The Attempt at a Solution λ = 343/283 = 1.21 m f(2) = 2*343/2*1.21 = 283 Hz. I'm getting...

Hello there! I have a couple of questions regarding the physics of sound (they may seem odd and concerning, but aren't for any malicious purposes, I promise, these questions just popped up in my head ) First, I'd like to understand how soundprofing works, the science behind it and how well can...

Homework Statement Two amplifiers can be used to power a sound system. Amplifier 1: Has a fixed power output of 300 W. Amplifier 2: Has a variable power output of between 15 W and 175 W. You may assume that the power output of the amplifier is equal to the power of the sound waves that are...

Homework Statement A radio speaker produces sound when a membrane called a diaphragm vibrates, as shown above. A person turns up the volume on the radio. Which of the following aspects of the motion of a point on the diaphragm must increase? a) the max. displacement only b) the average...

I collected this data by moving a sound level meter slowly through a total length of 0,75 meter between two speakers pointing towards each other. The wavelength of the sine waves was 0,343 meters and the frequency was 1000 Hz. The sound level meter measured the sound in dbA 20 times a second...

Hi guys I am having trouble determining a quite spot based on where you stand in respect to distance from the speakers. I have solved the question below but I need someone to explain to me how the "n" value can be used to determine a quite or not-quite spot. Am I looking for whole numbers? If n...

What is the reason making this sound?? ( Rotary lobe pump)

Homework Statement A person turns up the volume on a radio. Which aspects of the motion of a point on the diaphragm must increase? a. maximum displacement only b. average speed only c. both maximum displacement and average speed d. neither maximum displacement nor average speed Homework...