What is Sound?

[@huntingresonance]

Brilliant brilliant brilliant... there isn't another video on the internet that I've seen that goes into as much detail as this for longitudinal waves. It really is tough so times for students to grasp the relationship between different animations and representations. Thank you, this is spot on!

[@FlippingPhysics]

Thank you! I am really proud of the way I was able to start with the tuning fork animation, transition to the speaker, show the air molecules, and bring it back to the tuning fork animation. Glad you appreciate it!!

[@huntingresonance]

Genuinely though... it's really difficult to piece this all together and I really appreciate the effort you've gone to here to get it right and clarify it first time round.

[@freedomhq4075]

It is pretty great👍🏻 I agree

[@coachprovo]

This is way better than all of the "professional" videos that are out there. This is explained in the way that actual physics teachers talk with their students in their own classrooms. Thanks for putting this together!

[@FlippingPhysics]

You are welcome!

[@learningisecstatic9348]

As always I fall short of words to express my gratitude to your gigantic effort and passion to teach us. So just thank you again.

[@FlippingPhysics]

You are certainly welcome, again. 😀

[@lakshyatiwari1513]

Your pedagogical skills are really amazing. I never get bored in your lectures.

[@FlippingPhysics]

High praise. Thank you!

[@nn-tz7yw]

As a hs student and even now, I always valued understanding of a concept above simple memorization of test materials. Hence, I really love how you answer all these questions that aren't necessary for school, but help comprehend the phenomena intrinsically. As a student learning physics, I've always had deeper questions than what my teachers used to teach in class, but could only think of them to myself most of the time. Watching your videos truly quenches that thirst and fuels my "joy of understanding". I really appreciate your work and enthusiasm.

[@FlippingPhysics]

Thank you for your kind words!

[@LECityLECLEC]

your work is so beautiful!

[@zr7951]

All those animations are so hypnotic

[@joshuawilliams3221]

Absolutely amazing animations! Great work, thanks so much!

[@FlippingPhysics]

Thanks. I put a lot of time and effort in to them and I am glad you think it shows. Trying to play the all the air molecules moving in simple harmonic motion around the tuning fork actually crashed my computer forcing me to export 1/16th of it (20 degrees) and then duplicate that. Very proud, I am.

[@saketupadhyay]

Thanks a lot. What a crisp and visually appealing presentation. Keep making such videos❤🎉

[@sajidhaniff01]

Thanks! Awesome video

[@4568522012]

I love your socks and you make learning fun!

[@Kitchyyy]

love these videos

[@M2T6U8]

AMAZING!!!!!

[@jeffhampton6972]

This is excellent! I particularly like you qualifications of statements you make, and how careful you are with your language. This is really informative! I hope you don't mind, but I'm going to show this to my students today. :D

[@FlippingPhysics]

Please do! I make the videos specifically for teachers to use with their students. Thanks for the kudos!

[@shyamdas6231]

Thank you,sir!

[@FlippingPhysics]

You are welcome!

[@jlpsinde]

This is just amazing and genius. Thanks!

[@FlippingPhysics]

Thanks for the love!

[@shivpratapsinghsengar3743]

You sir is a legend 💪.damn you would be supper super famous if you were to teach in India.and yes insanely rich as well.great teachers get huge respect and bucks in here.

[@FlippingPhysics]

Perhaps I can be super famous in India even if I don't live there. Any clue where I can post my JEE/NEET playlists for better visibility in India? Thanks for the support!

[@srushtipednekar1136]

@@FlippingPhysics KZbin is a good platform sir... We would be really glad if you made vedios for JEE/NEET you make learning simple

[@FlippingPhysics]

​@@srushtipednekar1136 Almost 100% of the videos I have made and posted on this channel cover topics on the JEE/NEET. I even have playlists specifically dedicated to those curriculums. I think the issue is people studying for the JEE/NEET do not readily find them because they are more general and not JEE/NEET specific.

[@danielchen9841]

greate explanation

[@shailakamath9832]

What a fantastic approach to learning science.Just the way it should be done by asking every question that crosses your mind as you naturally try understanding the subject.These days science teaching in higher grades is mostly about memorizing a bunch of formulas to crack SAT and the like.One is much better off not taking that path as it simply kills our curiosity and enthusiasm towards learning this beautiful subject.

[@FlippingPhysics]

Thanks for the love!

[@ninoputso7265]

amazing video1

[@BoZhaoengineering]

When learning wave, we should have had this video for interpretation of sound as pressure wave.

[@ethanbruh3476]

3:00 A bee flew across the left speaker!

[@FlippingPhysics]

Actually, I am not sure what sort of flying insect it was. But realize, you are watching it fly by 32 times slower than real speed. I was amazed I caught it on camera.

[@wolfgang9190]

Fantastic!! Thanks a lot!!

[@FlippingPhysics]

You’re welcome.

[@saliqgowhar395]

Masterpiece

[@silverruby2003]

excellent

[@antoniodibacco8178]

Fantastic

[@ericperalesofficial8594]

So compressed and rarified? Don't they both mean to make something dense.?

[@darz_k.]

Is it technically possible to produce a tuning fork, with each tine cancelling out the other because of phasing, thereby creating a tuning fork that seems to make no sound when clanked?

[@kb98765]

Brilliant video. Teaching needs empathy foremost. You nail it with the three levels (level here doesn't mean intelligence) of students. Individually we all have questions of all three students. I have one query: how did you make that air molecules animation of linear and circular kind showing compression waves? I want to make something like that with shock waves. I was looking for non-linear wave steepening which leads to shock waves. I can't find it. So I want to make one. Advise please.

[@RedVenomProductions]

If I’m not mistaken, the complex waveforms that come from our voice box or other sounds should just be the addition of sin waves at different specific frequencies and at possibly different amplitudes. Though cool video though. Pretty nice improvement.

[@FlippingPhysics]

What you have stated in your comment, and what I said in the video, "most sounds are not a simple sinusoidal wave form like the one created by the tuning fork. For example, the sound wave created by my voice right now is very different than a sinusoidal wave, however, it is still comprised of changing air pressures which also has a wave form, it is just that wave form is much more complicated than a sinusoidal wave." Are not mutually exclusive.

[@carultch]

What you are referring to, is called the Fourier series. The concept that other shapes of waveforms can ultimately be treated as a superposition of sine wave component waveforms, that add up to form the exotic shape of a waveform, like that in a human voice or a musical instrument. The way you can tell the difference between a flute and a trumpet both playing the same note, is by perception of its Fourier series and wave shape.

[@arandomone12]

These videos are super helpful! Also, do you make your animations using After Effects? Thanks!

[@ishaansubudhi7248]

I just realised that your students are the same person!!!

[@FlippingPhysics]

Are you sure? flippingphysics.com/making-a-video.html

[@carultch]

@@FlippingPhysics I thought Billy, Bobby and Beau might've been three of your brothers who look similar to you. That's impressive how you've video-clone yourself and act out the roles of the three different characters.

[@matteo5399]

Thank you for the really useful video ! On the graph you showed for the pressure of a sound wave, what would the variable in the x direction be ? Is it the displacement from the sound source? Is it time ?

[@FlippingPhysics]

The truth is the horizontal axis could be either distance from the sound source or time.

[@aliabas2121]

Can you make a video on speed of sound at diferant temperatures mathematically

[@carultch]

The speed of sound in general is sqrt(bulk modulus / density). Bulk modulus is a measure of volumetric stiffness: i.e. how much pressure it takes to change an object's volume, per unit volume. For gasses, there are two types of bulk modulus at any given condition. There is the isothermal bulk modulus (constant temperature), and the adiabatic bulk modulus (no heat transfer). We can either consider compressing gasses slowly that all possible heat is exchanged with the surroundings, or we can consider compressing and expanding gasses quickly that no heat has time to transfer. It turns out, that it is the adiabatic bulk modulus that matters for speed of sound in gasses. Isaac Newton tried to determine the theory of the speed of sound in air, assuming an isothermal bulk modulus, and was unsuccessful at getting it to be consistent with experimental results, consistently with a 20% error. Laplace was the one to figure it out what Newton missed, and by using an adiabatic model, could determine the true theory behind the speed of sound. From the theoretical model of speed of sound in an ideal gas, speed of sound is given through c = sqrt(gamma*R*T/M). The value of gamma is the adiabatic index or heat capacity ratio (1.4 for diatomic gasses like air), R is the ideal gas constant in J/kmol-K, T is the Kelvin temperature, and M is the average molar mass in kg/kmol. Since sqrt(1.4) is close to 1.2, this explains why Newton consistently had a 20% error.

[@Gàurav-v2x9h]

What is energy.

[@fynriel2678]

I have a stupid question: Why do the particles move back at all? They are pushed away/displaced and hit another particle. And then they travel backwards? Why?

[@carultch]

If the particles were not moving at all, the blood in your hand would freeze solid if you touched such an object. It would be at absolute zero, at 461 F (273 C) below zero. The thermal energy of an object takes the form of its molecular motion. The thermal motion is scattered and chaotic, and on net, the molecular motion of a stationary object adds up to zero, which is why you don't see static air masses actually moving. Sound waves propagating are a form of organizing this energy in compression and expansion patterns, displacing it from its steady state pattern that it would otherwise have, if there were no sound.

[@fynriel2678]

@@carultch I appreciate you replying. Thank you so much. However, I still don't understand what causes the air molecules to compress and expand. Once a molecule is hit "from behind" and pushed forward, as seen at 3:30, what makes it return to its original position? Why wouldn't it simply return to its chaotic movement pattern?

[@carultch]

@@fynriel2678 The air molecules are having elastic collisions with each other. I.e. a collision that restores all kinetic energy, like ideal billiard balls. The air molecules initially pushed forward by the speaker membrane, have a collision with the initially "stationary" molecules directly in front of them. This collection of elastic collisions will "passes the baton" onto the next group of molecules to carry the wave. The previous molecules will become "stationary", as the new molecules carry the wave. The reason the molecules eventually move back to their original position, has to do with why I put stationary in quotes. No group of molecules is really stationary, but there is a Maxwell-Boltzman distribution of speeds among them. Some are initially moving backwards, some are initially moving forwards, and on-net, their motion adds up to zero for air masses that I'm calling "stationary". Those molecules that were initially moving backwards in the subsequent air mass, will cause the original sound-carrying air mass to bounce backwards and fill the void they would otherwise leave behind.

[@fynriel2678]

@@carultch Okay I think I’m beginning to understand it a little better. So is it correct to say that: 1. The molecules are moving about randomly even after they collide with the ones in front of them, and only some of them happen to also move backwards (where they will them then collide with the original sound carrying air mass)? 2. Since air was displaced it needs to fill the void thay was created immediately (why is that btw?) so that would be another reason why some molecules have to move backwards again?

[@carultch]

@@fynriel2678 Yes, both explanations are correct. As for why the molecules will fill the void, in concept, they don't necessarily have to fill it. It is just statistically likely that they will, given the massive number of molecules in each milliliter of air. It would be big problems for the second law of thermodynamics, if air molecules were "lucky" enough to all of a sudden form a void, completely by happenstance. As crazy as this sounds, the kinetic molecular theory doesn't directly forbid it from happening. The second law of thermodynamics that is what ultimately requires air to expand to fill voids, is more of a law of what is statistically likely to happen, and for all practical purposes, tells us whether it is possible or not at the macroscopic level.

[@MIS491]

if tree falls in the forest and no one is there to here it, does it make a sound? wanna know though

[@BanValsimot]

I have a tinitus, I hear high frequency sound waves all the time. But my question is: if I make a sound with a friction, if I move the brick over the stone surface or whatever, will this pressure waves that make a sound be created by oscilations of the objests surface molekules or by something else? What else can be vibrating there to make the air vibrating? Or will surface roughness of the objects compress the air between two objects and that air compression will spread? How does it work? :/

[@gurnoorarora1850]

For more attention from JEE preparing viewers kindly add JEE along with the title . It will help :)

[@FlippingPhysics]

I've been trying that with all the videos I have released in 2020 and my SHM playlist. As far as I can tell, it has not increased views from those preparing for JEE/NEET. Did you find my videos through a KZbin Search for JEE?

[@gurnoorarora1850]

@@FlippingPhysics I am preparing for jee but I found your channel much before than that.. Btw thanks for making physics videos like these I really enjoy watching them& even my friends do watch them thanks!

[@FlippingPhysics]

Best of luck on the JEE!!

[@gurnoorarora1850]

@@FlippingPhysics thnx!

[@davidkatuin4527]

Best breakdown l have seen. Is the energy kinetic energy? I have another visualization with a pool table and some billiard balls. My brain sometimes won't let me sleep. Thanks for your animation . It should allow me to sleep for now.

[@carultch]

Sound waves are ultimately kinetic energy. In solids and liquids, sound is a continuous exchange between elastic potential energy and kinetic energy. In gasses, it is completely kinetic energy, except for the tiny nanosecond (could even be less time than that) when the molecules rebound off each other, where it temporarily is potential energy. No individual sound molecule necessarily makes it from source to receiver. Instead, it is a wave of elastic collisions among the molecules that carries the sound energy.

[@christosnettos9493]

Does anyone know which program does he use to create this animated videos?

[@danielchen9841]

greate class with greate teacher all the student are greate🤣🤣

[@neyvickzallescardenas5327]

Hey profesor could you make a video about guitar coils and how they change the sound to a voltage please!!!!! And maybe explain the frecuency that certain coil works please!! Fuking love your vids!! Also the ecuations.. (sorry for my english not native speaker)

[@FlippingPhysics]

That concept is outside the curriculum I am currently working on. At some point I will certainly make that video, however, it is going to be a while.

[@neyvickzallescardenas5327]

@@FlippingPhysics thats ok ill be waiting

[@carultch]

@@neyvickzallescardenas5327 The fact that the strings are steel is part of the reason. The strings can be any ferrous metal. Steel is the most common choice, although nickel electric guitar strings exist as well. If you strung an electric guitar with non-metal strings like nylon, or non-ferrous aluminum or silver strings, it wouldn't work. The strings have no initial magnetism of their own, but when allowed to interact with magnetic sources, they will influence the magnetic field. What happens is that the guitar string becomes closer and farther away from the magnetic pickup, that it influences changes in the magnetic field surrounding the permanent magnets. When changes in the magnetic field are detected, Faraday's law of induction picks up an induced EMF as a result of the time-varying magnetic field. The coils in the pickup act like the secondary of a transformer, collecting this EMF as a voltage waveform, that is representative of the sound wave corresponding to the vibrating string. The electric signal directly from the guitar isn't enough to power a speaker. As such, the amplifiers will use an operational amplifier circuit (op-amp) to boost the signal. You can set up the amplifier circuit to either boost the signal in an exact proportion as the original signal picked up in the coils and get the clean sound. Or you can amplify beyond the capacity of the circuit, and clip the tops and bottoms of the wave, to get that characteristic rough distortion of electric guitar music.

[@ahmed13566]

I want ask you one question if you don't mind. You know that any material has molecules and any molecule has atoms. So any molecules of any material in a state of constant motion ✍️ So you know that the middle is a matrial. So the molecules of the middle in a state of constant motion. How they say that the molecules of the middle that the wave move from not move it just make vibration around her resting place. Can you answer on my question??

[@ahmed13566]

And I want know what the mean of vibration If it mean move from one place to anther or what.

[@tejabavanari8534]

hw has a really damn steady hand tho

[@FlippingPhysics]

so true

[@Gimpenn]

My teacher asked us what sound is and every time we said like with sound waves and air he just said “How”

[@zakiatabassum9549]

I have so many questions for whoever it is that disliked this video...

[@FlippingPhysics]

Yeah. I wish I could ask them...

[@pokemaster6101]

Stop hearing it at 17k :(

[@emilyli5179]

*cannot hear the sounds after 15000Hz*

[@FlippingPhysics]

Yep. That's presbycusis. Hopefully not voluntary, early-onset presbycusis.

[@kixdeafmonkeys2743]

Your room sounds in B :)

[@ahmed13566]

And anther question : Any wave comes from vibration okay and it makes vibration for the molecules of the middle it will move from. So it comes from vibration and akes vibration. Is that what happen in realistic life or what? And if that true what I said how does Electromagnetic wave comes from vibration If they mean that it comes from vibration of her magenitic field and her electrician field It not makes any vibration of any middle as it can move in space. Ao why they say in the definition of the wave that the wave comes from the vibration of any molecules of the middle. But what about Electromagnetic wave Or they mean if there is a middle it makes a vibration of it And if threr is no middle it can move in space. It is not care about that. 😂😂😂 I know it is alot of questions but what can I do they must clear any theory or any law they put in the life