What is Heat? (Thermal Physics)
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- เผยแพร่เมื่อ 14 มิ.ย. 2024
- The concept of Heat (noted Q) is central to many areas of physics: thermodynamics and thermal physics of course, but also astrophysics, materials science, engineering and many more. It is heavily used also in other subjects like chemistry, biology, geology etc.
In this video, you will discover what heat is exactly: a non-mechanical transfer of energy from a hot object to a cold object. This is why, in the first section of the video, a precise definition of temperature is provided. Then, the concept of heat is detailed by looking in detail what happens at the contact-interface between two solids at different temperatures.
*** Content of this video ***
0:00 What is Heat? - Introduction
0:47 What is temperature?
2:29 What is Heat? - interface between two adjacent solids at different temperatures
6:11 What is Heat? - Official definition and discussion
7:23 Behind the scenes…
*** Credits ***
Music by Edouard Reny.
*** More Info ***
This video is produced and presented by Edouard Reny, Ph.D. in solid state chemistry and private tutor in Physical Sciences.
For access to great resources that will help you with your studies of high school Physics, visit and subscribe to the "Physics Made Easy" website:
www.physics-made-easy.com/
Edouard provides one-on-one private tuition in Physics (face to face or by Skype). If you wish to contact him, visit his website: www.physics-tutor.nl/
Sir, you are the real Messenger of physics on earth! God bless you!
The messenger of Physics on Earth? That might be a little too much haha, but someone that loves Physics and wishes to inspire the fascination for our the universe works to other, yes :-)
I wonder why your channel don't have enough subscribers because it's always been useful for me in my studies and I understand the concept so clearly
Hats off your Teaching!!
Thank you Prachi for your comment: It shows that I am reaching my goals :-)
This channel deserves more appreciation ❤️🔥
Thank you for your kind words Zoe!
This channel is so underrated... It's so sad.
I love this channel and it makes physics easy for me... I am really more thankful to him than my college teacher... Big Respect... And love and prayers. ❤️
Thank you for your kind words. I am glad my work allows you to get a better grasp of Physics!
You are really making physics easy , thks
I appreciate your contribution. It's really fun and a great way to learn physics. Thank you so much
Hello Ramsaha, thank you for your kind words. I am happy you enjoy the way I approach teaching physics.
Absolutely love the way you explain everything! Thank you.
You are welcome Fatyma. I am glad you enjoy my work.
I have been studying from videos of yours, your teaching is amazing and excellent. I salute you, professor.
Hello Minty, thank you very much for your encouraging words :-)
Finally i found experienced mentor who made things simple and clear!
Question: can we consider oscillation of molecules gives heat and oscillation of electrons gives Electromagnetic waves?
Thank you for your kind words Ajay !
If a particle (or a spring) oscillates it means it has energy (when you position yourself outside of that system, this energy is called internal energy). Thus, a molecule A that oscillates has energy.
If the surrounding molecules oscillate less than molecule A (lower temperature), then molecule A will transfer some of its energy to the surrounding (like a fast ball hitting a slow ball gives it some of its kinetic energy). That energy transfer is called heat : Molecule A heats up the surroundings.
If that molecule is charged, the electric field it generates, seen from a fixed point, will appear to fluctuate. From that fixed point you will perceive an EM wave.
The amplitude of the oscillations will be larger for an electron than a charged molecule, because the electron is lighter (F=ma). This is why we usually refer to electrons oscillating because they contribute the most for example in reflection. However molecule oscillations can have a strong impact in certain areas (this phenomena is responsible for the green house gases effect).
A very cleaned presentation.thanks a lot
You are welcome Mayu!
Thanks for the help..🙂
You deserve more subscribers!
Super video sir. Thankyou very much !!!
Perfect information keep up... Thanx
Thank you Jassar for the encouragement!
Great video Edouard
Merci Victor ;-)!
Very helpful video. I was looking for a good explanation of how heat works and I found it. I look forward to checking out more of your videos on your channel.
Thank you Eric, I am glad you found this video useful :-).
Nice lesson Prof.
Great job! Thanks a lot. A very clear and concise lecture.
Thank you, I am glad you enjoyed it.
Amazing video. Yes, I imagine editing is a pain! Must take 100x effort involved in simply shooting content. The layering of concepts was very succinct and effective for me (from the individual particle bond to the nature of a system, for example). I particularly appreciate you highlighting the misleading term "non-mechanical." Many of your videos (from my vantage point) highlight nuances well beyond textbook physics, which is just really cool because it for me it creates room to ask questions that otherwise were not possible or perceptible. I will have to find the other example of such a nuance I am recalling but in general I keep seeing it in this content and it is really awesome and keeps us viewers thinking newly. Thanks for the hard work and time. Incredible channel.
By the way - my personal opinion - I do not feel the animation was lacking. I think the ideas/architecture behind the animation are very thought out and precise, so simplicity is actually helpful for me in my learning style. Ie - no excess information in language or visually.
Thank you Nimisha for the very kind words. I am really glad that my videos allow you to develop your own thoughts about how this amazing world we live in works. I appreciate also how you recognise the thought process behind the structure of the videos: You are not just gobbling up, but being quite attentive to the content and its meaning, and that I value highly!
Fascinating content. Thank you, professor, from Albuquerque, USA
Hello Randall. you are welcome, I am glad my fellow science enthusiasts the other side of the pond appreciate my work :-)
Good job❤, it is really helpful and beautiful.
So good
Thank you for the videos sir.
You are most welcome!
what a smooth explanation. informative, interesting and concise. 👌
Thank you Gurmel, I am glad you enjoyed the approach I took in this video :-)
What a great presentation on this topic!
Thank you for your feedback. I am glad you appreciated the video :-)
This actually makes me consider studying physics
Hello Aaron,
Studying physics is like a rough hike in the mountains. Tough to get to the top, but once you're there, you get amazed by the view. (It had this effect on me: physics was rough for me as a student, but I held on, and didn't regret it!).
Enjoy!
So simple explanation. Thank you and may God bless u. Lots love from me...💚💚
You are warmly welcome Muhammad. Thank you for your praise :-)
Hey man, You are brilliant! from India
Thank you Bilujiluaju :-)
The topic is presented and explained well, looking forward for your other videos 😊
Thank you Misty
Thank you sir
You are really awesome, u r really making physics easy.
Thanks a ton for your kind words Sudhir!
THANK YOU really helps😊
very clear explanation
Thanks!
Your videos are just INCREDIBLE
Thank you Ahmed! Most appreciated!
Thanks for your effort
Thank you Amri!
Great video, keep it up!
Thank you Nick :-)
great!
Awesome video...keep up the great work
Thank you Anik
Your teaching style is excellent.Waiting for your more videos
Thank you Rodney
I can't thank you enough for the 'Work' you've put into your channel! Your videos help en'Light'en me to perceive our physical world through a clearer lens. Thank you!!!!❤🔥
Merci Felizel! These were beautiful words to read. I am glad you enjoy my videos :-)
Lovely video 🙂
Thank you Man!
You are the best❤
awesome video
Thank you Unique
Thank you very much!
You are welcome Cartel
Well explanation sir🙏 watching from India
Thank you Mahanthesha. Greetings from France :-)
good explanation.. I watched your many video,every video was excellent.
Hi Khalid, I am really glad you enjoy my work! Thanks!
Thankyou so much .I got great opportunity from this 🙏
Nice explanation.. kindly upload more lecture
You are welcome Rajeev. Will do and don't hesitate to explore the channel for what's already there!
This is a really good video thank you so much, you have some of the best explanations I can find!. God bless ^^.
I am glad I could help Chris. Thanks for the encouragement.
Thank you!
You are welcome Caprice :-)
Keep going sir!!!!
Thank you for the encouragement Adhih
Best one!!!! ❤️❤️❤️
hot / cold in an every day context can also be defined as the perception of difference in particle movement compared to your body. uncomfortably hot means so hot that the subatomic processes in your body are affected negatively by being forced to move quicker than ideal to a point where it hinders subatomic reactions in molecules in your body. the same is true for cold, only that it slows them down to a point where the subatomic particles are prevented from or at least hindered to perform their reactions properly or at the right time, speed or rate.
The reason it feels nice to be exposed to heat after waking up, in the shower or when you were exposed to the cold is because the body requires less energy to maintain your body temperature so its produces hormones to reward you for staying in the heated area, especially when your metabolism is trying to wake up and come online after being shut down over night. Thats why cold showers are stupid in the morning. they force your metabolism to accelerate much quicker than with room temperature so the body has to work a lot harder, and the body can not keep up for a while, which is why its so uncomfortable. Instead, people should start out with warm water to help speed up enzymes and reactions before your metabolism is fully awake, and then after its fully working, then you should progressively lower the temperature to make it go beyond the normal level. you avoid all the uncomfortability and when you are exposed to room temperature again, you will be much more awake and capable for a while compared to just cold showers.
Hi, very good comment!
I especially agree with your last statement about the morning showers! When the weather is warm (Spring/Summer/Autumn), this is what I do in the morning to 1/be kind with my body and 2/ wake it up! :-)
Thank youl
I am an engineer since 9 years .. and I find your videos very informative .. specially those talking about em propagation and light ...
please keep up the great work :) .. now looking for Enthalpy and Entropy (if I won't be demanding :D) .. THANK YOU SO MUCH
Hi Ibrahim. I love reading these kinds of words from experienced engineers and scientists. It is basically praise from my peers! Yup, enthalpy and entropy. That's a good idea. I'll put it on the list to keep it in mind. Thanks for the suggestion!
@@PhysicsMadeEasy 🌹🌹
Please don't stop making those videos. Thanks for reading.
Thank you Alan! I am currently ultra busy, but hopefully by beg next year, I will be able to resume :-)
Respected sir, I have some questions, it would be very helpful if you could answer for me,.... 1)Is it possible to produce em waves by oscillating the magnet to certain frequency?....are we producing em waves in faradeys law to induce EMF in another circuit? please explain how it works sir
2)Can we produce em waves by oscillating the vandegraff generator?
3)where does the energy of em wave come from? How accelerating charges losses it's energy so that it gives to the em wave? if I take an electron and jiggle it... How do I lose energy to give to em wave....
4) how can an object obsorb the em wave...what does black body do when em wave falls on it,why does atoms of black body does not oscillate to the incoming em and produce its own em wave, does it produce out of phase light wave which destructively interfere on incident wave...how can a em wave be obsorbed/destroyed?
5) according to classical model of atom, how electron rotating around nucleus losses energy...it's accelerating but what's the OPPOSING FORCE that causes the ENERGY TO DECREASE/ tangential velocity to decrease and fall into the nucleus??
6) does all AC circuits produce em waves, will AC circuit glow visibly when its frequency is frequency of visible light....why DC current does not produce em waves.... even though electrons collide with nucleus of the conductor and losses energy and ACCELERATES?
7)Why cannot neutral objects (Eventhough having positive and negative charge) does not produce em waves ...is it possible to produce em waves by shaking the a ball with our hands or machine to vibrating the neutral object to certain high frequencies...??
Thank you sir
1)Is it possible to produce em waves by oscillating the magnet to certain frequency?\
Yes, but this is not because it is a magnet… all materials contain electrons, so all materials would emit EM waves if the material is subject to a physical oscillation. Note though, that the EM waves of positive charges and negative charges in the object would interfere, but not completely due to phase differences. (all charge carriers are not at the exact same location)..
....are we producing em waves in faradeys law to induce EMF in another circuit?
In a dynamo for example, where you produce AC current, yes, because an AC current is electrons are oscillating around a central position
2)Can we produce em waves by oscillating the vandegraff generator?
In a VdG generator, yes but indirectly: it produces a very high Potential difference, by ionising the molecules, sparks are generated, which emit light.( EM waves).
The current itself, even if DC, is a motion of charged particles, therefore, it can generate a change in the electric field in the space surrounding the electronic flow at the condition that such current is not perfectly stable.
3)where does the energy of em wave come from?
The fluctuating electric field (EM wave) is generated by the oscillation of charge carriers. In order to generate this oscillation (and maintain it), some work must have been done (and be done) on the charge carriers.
4) how can an object absorb the em wave...what does black body do when em wave falls on it,why does atoms of black body does not oscillate to the incoming em and produce its own em wave, does it produce out of phase light wave which destructively interfere on incident wave...how can a em wave be obsorbed/destroyed?
Many question Gowri! Check my videos on black bodies.
The black body phenomena is basically a quantum mechanical effect, that can only be partially explained using classical physics: the energy of the absorbed EM wave is converted to the kinetic energy of the BB’s particles. Therefore the internal energy of the BB increases (that includes the KE), thus temperature. Consequently, the particles move more, and because they carry charges, they emit light.
5)can linearly accelerating, circulating, spinning charge produce light? How will that light look like?
A charged particle accelerating, or even just moving, will create a change in the E Field strength at the points around it, so yes. For spinning particles, it depends of the distribution of the charges within it (if perfectly homogeneous, it can be considered like a point charge not moving, therefore, no EM fluctuation)
You are maybe referring to probably to synchrotron radiation (charged particles circulating in a loop). I invite you to search for this term on internet.
6) does all AC circuits produce em waves, will AC circuit glow visibly when its frequency is frequency of visible light....
Yes
why DC current does not produce em waves.... even though electrons collide with nucleus of the conductor and losses energy and ACCELERATES? \
Yes they do, but these are not wave-like, more like EM fluctuations.
7)Why cannot neutral objects (Eventhough having positive and negative charge) does not produce em waves ...is it possible to produce em waves by shaking or vibrating the neutral object to certain high frequencies....how black bodies produce em waves??
Even if an object is neutral, it does consist of charged particles (electrons, quarks). So yes, if you were able to jump up and down a quadrillion times per second, your body might glow! But as mentioned in the answer to your first question, the signals from + and - charges would interfere destructively, because oscillating with the same amplitude and frequency. However, a small phase shift due to different position of these charge could allow you to detect a weak signal (the interference is not fully destructive). In other words, the glow of your body would be barely detectable. ;-)
@@PhysicsMadeEasy THANKS A LOT SIR, FOR SPENDING YOUR VALUABLE TIME TO ANSWER MY QUESTIONS...YOUR ANSWERS ARE GREAT🎉👍🌟🌟👌🙂
Waiting for more videos.. 🥺🥺
You and others have made me move myself, there is a new video coming out soon!
Thank you for producing such clear videos. I have a question. When heat is transferred to a molecule, is the energy stored by the electron and\or nucleus jumping to a higher energy level? 💫 Any insight as to what is going on at the fundamental level would be appreciated. Thank you.
It is possible for heat to make an electron jump to a higher orbit, i.e. to the atom to jump an energy level, that is what happens at the surface of stars (some absorption lines therefore disappear leading to categorizing stars in spectral classes).
But at theses temperatures, molecules do not exist. heat provided to a molecule will increase the KE (and the PE) of its bonds. However, because some modes of vibrations can be favored, it is possible to consider defining their energy with quantized levels. In solids, we even talk about phonons (this is not a typo, phonon with a n), as particles of soundwaves...
Awesome video on heat! Would you be able to make a video on enthalpy and its relation to heat? I believe enthalpy is the energy within molecular bonds, so it would be interesting to see how that is related to heat.
That is a good idea, I will put it on the list. But as a quick fix, the relation of enthalpy with heat is that the change of enthalpy of a system is equal to the heat provided by the system, when the system is at constant pressure (example: when the system is open to the atmosphere).
At P = constant: dH = dU+PdV = dQ+dW+PdV= dQ-PdV+PdV = dQ
Heat and Freeze, is the Two Legs,
the Stuff-side of Life, 'Walk On',
they is Stuff-side of Eternal Abilities,
Gravity and Feeling, Instinct keep them
in a balanced tension.
Wow… love and respect from India 💯😍
Thank you!
A very good presentation. Thanks! By the way I’ve bought your course on the basics of electricity on Udemy. It would be a good idea if you will make other Physics courses on Udemy.
HI, Thanks! I hope the course was useful to you, don't hesitate to post a question on Udemy if you have one.
Yes, I know, I should create more courses, but these take a huge amount of time to produce, and I have to take care of my real life students and many other things going on in my life these days :-)!
I would love to do more. and I plan to do so. The one I have in mind for the continuation of the one you purchased is electricity Part 2 (Electric potentials, electric potential energy and circuits).
But it 'll have to wait a little...
Thanks for your encouragements!
@@PhysicsMadeEasyThank you Sir , may Allah Power to accept Islam❤🇵🇰
Hey sir...for the first time in my life I started to feel EM waves by watching your video...can u please make more videos upon the phenomenons of waves like interference, diffraction and all....please..
Hello Adarsh, thank you for your words. There are already quite a few videos about waves. See the Waves playlist of the channel:
th-cam.com/play/PLU0ETLdKNmc5W6gduim48-b1hP5nGa1EH.html
Thanks also for your suggestion. Adding a few more 'Wave' videos is on my plate for 2022...
@@PhysicsMadeEasy thanks sir
Sir you are really amazing...i had some wrong preconception regarding heat...Hope u are working more on your animation skills....ciao
Yo Johan, thank you for your kind words.
As for the animation skills... it's stagnation lol! And besides, having limited tools at my disposal forces me to remain creative :-)
Finally I got Answere! 👍
Super! My work reached its objective!
Great Explanation Video..Thank You Sir. ❤️ From India.. Sir it will be great for us if we get more concept videos for JEE and Neet from You.. Humble Request 🙏🏼
Hi Swarup, i actually focus most of the lesson videos on the basics of physics, which are common to all curricula. I prefer teaching the real foundations, and then at the light of the new understanding these provide to students, students can review their own notes. They can use what they learn with me to understand better what is taught in class.
I try to make my videos conceptual pillars on which students can cling too, but its up to student to adjust to his curriculum philosophy!
@@PhysicsMadeEasy That's great Sir..We appreciate.. Concept is the most important while solving a numerical...Thank You Sir... Eagerly Waiting for more videos to know something new and the basic concepts...We are getting the answer of why and how from your videos.Thank you for that sir
*The Heat: 🚨*
*Heat:🔥*
Respected sir 🌟,, As galaxies and planets , Stars near our solar system is moving away from us in an INCREASING RATE In the expansion of universe(due to dark energy).....Will Astronomy(observing of stars planets and galactic events) become more and more difficult in future days?
Thank you sir 🌟
Hi Gowri, absolutely… at the condition that the acceleration keeps on (which, today, is believed to be the case as dark energy doesn’t seem to be diluted with the expansion of space),
But non worries, we , or the Earth, or even the Sun will not be there to observe this darkening of the sky.
Imagine though if humanity had emerged much later in the life of the Universe when the observable universe was limited to our galaxy… We would have never had the chance to understand the cosmos as we do!
Thx you soo muchhh it's helped me so muchhhhhhhh ,😭😭😭😭😭😭😭
Hello Rizna... please don't cry, if it helped, you should be happy! thanks for your comment :-)
Sir I am from India..I really like and love the way you teach physics. But Can you please make a video on Simple Harmonic Motion, rotational motion and related concepts and on mechanical properties of fluids and solids. I haven't found those videos on you channel.
Thank you!
Hi Rajin, thanks for the suggestions and put on the wish-list. You might find some circular motion videos in my very first videos. I produce a video when I have some time to spare (1 video = about 40 -50 hours work), so of course you will not find all of physics on that channel. But step by step, little by little, the catalog gets thicker :-)
@@PhysicsMadeEasy Okay Sir..
Sir, I always struggled to understand how transfer of energy between particles takes place inside of an object when two molecules or atoms in any object don't physically touch each other.
Does it mean that electromagnetic radiation takes place within the object as well?
If it is the electrostatic repulsive force that pushes the neighbor atoms/molecules then how do the particles (electrons) on the surface (opposite to high energy surface) radiate energy if they didn't absorb any energy? Vibration of bonds and atoms and molecules does not explain how electrons are absorbing energy (quantized energy) to radiate the energy in the form of EMR.
NOTE: I may have not been able to explain very well what I mean but I am sure there are others also who don't understand this.
In the video, I was considering energy transfer by conduction (a model where particle actually collide with one another). I understand you are referring to radiative energy transfer. Watch my video « What is an EM wave » and you will understand how this works.
The confusion that you experience might come from the fact that you are blending notions of classical physics and quantum mechanics. In classical physics, radiative transfer is considered to be occuring via an EM Wave (See the video « why does light reflect ») for an example. In quantum mechanics, radiative energy transfers occure by exchange of photons between the interacting particles (i.e. exchange of quanta of energy that we perceive as light).
Does this answer your question ?
i am from india sir you are great
Thank you Nishant
I love this presentation because explains the heat in the case of solids in a easy to understand way.
Thank you :-)
Dear sir, I want to ask you one question please reply , when a particle move then it's mass increases, does this mass increase refer to matter increase or this is just because mass is a relative physical quantity , does movement add new particles to the moving object?
Hi Rahul,
Mass is the property of an object or particle. It does not in any way represent the amount of matter (saying so is just an approximation practical for low energy sciences like chemistry).
You have to see mass as a form of potential energy. At rest, this energy guarantees the cohesion of the particle. It is called rest mass.
When you accelerate a particle, you transfer energy to it and it gains Kinetic Energy 0.5mv^2. At low energies, what increases in the formula is the speed v. But if you transfer more and more energy, you realize you will hit a problem: You cannot increase the speed more than the speed of light, so where does the energy go? It is converted into mass.
The process is progressive actually. Larger the speed, large the fraction of the energy that is converted to mass instead of motion. Approaching the speed of light, most of the energy is converted to mass. More info? Check this link:
courses.lumenlearning.com/boundless-physics/chapter/relativistic-quantities/#:~:text=The%20kinetic%20energy%20is%20equal,the%20velocity)%20of%20the%20body.
I hope this helps!
Sir can you please explain difference between potential and potential energy.
Hello Ganganna.
Potential energy is an energy and is expressed in Joules.
Potential is an energy per unit charge (or per unit mass). It is assigned to a position, not an object. It corresponds to the potential energy an object would have placed at that position per unit charge (or per unit mass).
Example: A position in an electric field has a potential of 5 joules/Coulomb (= 5 Volts). A charge of 3 Coulomb placed at this position would have a potential energy of 5 x 3 = 15 Joules. (15 joules of energy were required to bring it there from infinity)
Check this video where I deal with this question in detail: th-cam.com/video/j3GrOKre__0/w-d-xo.html
Sir I have a question about centripetal acceleration.
The formula that we are provided to calculate centripetal acceleration is v²/r. But sir as we know that when an object is moving along a circular path with a constant linear velocity it's direction only changes but the magnitude remain the same sir but when we calculate the centripetal acceleration through this formula then we get a neumerical value ,say 1m/s² but my question is that what it conveys to us as the speed is constant so there is no magnitude acceleration and how it tells about the change in direction?
Hi you have to think in two dimensions: the centripetal acceleration (v^2/r) is perpendicular to the velocity of the object in circular motion. This is why the speed doesn't change. On the other hand the acceleration will 'pull' the object towards the center., this is why the velocity changes direction.
In fixed cartesian coordinates it is much more complicated to define than in a moving cartesian coordinate system (as we do in a circular motion perspective). But it can help answer your question:
Imagine you throwing an object, this object will move horizontally, but gravity will pull it down at the same time. You are using here a fixed coordinate system. Now imagine you throw it very hard, with a very large initial velocity so that the curvature of the earth is too small so that the object falls continuously (the object is in orbit). Now think about what happens in time to the coordinates of the velocity vector within a fixed cartesian coordinate system. You will then realize that the magnitude of the velocity vector stays constant, but its direction changes.
😍🥰
Would dried food and roasting is better or fresh steam food. Because frozen food and canned food seems like dead food? Because no heat to begin after frozen
I love to cook, But I cook French (I am French), so your question is a little out of my knowledge!
An example: Bread. Baguettes, it's nicer when just fresh from the baker.
If I deep freeze it and then heat it up, it's not as good.
Except, when I let it unfreeze slowly under the rays of the Sun. Then, it's better than fresh. I do not know why, but I find this little thing I discovered amazing!
Respected sir 🌟, Its know that Diffraction is an property of wave, but light behaves as particle (photons) at shorter wavelengths...Compton scattering using X rays is an example of particle nature of light....then how does X rays(very short wave length)produce Diffraction pattern in crystallography? How can same X-rays interact differently in these two cases?
Thank you sir 🌟
Hi Gowri,
"but light behaves as particle (photons) at shorter wavelengths"
It also behaves as photons at longer wavelength (think photoelectric effect with visible light)). All is a question of the experiment you are carrying out.
The diffractive nature of light will show up most when the size of the slits (for X-Rays, the interatomic distances) is of the order of magnitude of the wavelength. That's why we use X-Rays to probe the structures of materials.
Sir plz make one video on Alternate current we want to feel that too...
Thank you Adarsh for the suggestion. I added it to my "would like to produce" list
@@PhysicsMadeEasy thank u sir
@@AdarshKumar-gq9bwufjvhkl
I have a query but it is off topic
→in our textbooks there was a formula *work done=(force)(displacement)
But if we consider a vaccum for example space than, if we apply a litte force it will start to move and as there is no friction at all so it will move in a particular untill an external force act on it, so displacement will approach infinity. It means work done = infinity ♾️.
But on another hand if we consider a heavy box on a surface with a higher amount of frictional force (static) let's say 1000N and if we try to move it with a force less than 1000N, it will not move, but in this case we have chemical energy in our body and we are using that energy to apply the force, but the box is not moving. So the work done = 0, but where does the chemical energy went. Is it violating the law of conservation of energy?
Be careful W = F * Displacement during which the force is applied on the object: In space, you apply a force of 100N for 10 meters on an object initially at rest, then the work done is 1000J, and that will be the kinetic energy of the object. Once your stop pushing, the object will continue to move (to displace) with a KE of 1000J until another force modifies its motion. If no forces show up on the way, it will move for infinity as you say, but the work done (and the KE) remains 1000J because you applied the force for only 10 meters.
For the second question: The box remains still but stuff is still happening. At the interface friction acts like a reaction force opposite to the applied force. You are actually compressing the box, as if you were pushing it against a wall. Think of the box as a spring of very high spring constant. The chemical energy you used goes into the internal potential energy of the box. No violation of the law of conservation of energy in sight ;-)
@@PhysicsMadeEasy Thank You Sir
I am very grateful to you for solving my doubt.
And your explanation is outstanding and no one can copy you.😀😀
Sir video is very nice and sir please make a video on quantum field theory and please tell us ,are fields real or just mathematical construction to understand the particles
Hi, a video on quantum field theory? Maybe one day, but until then, if you are interested in that topic, check the PBS space time channel. They have great videos on that topic!
As for the reality of fields... this is a big question, philosophical even. imho, they do exist physically. Particles, on the other hand, do not really: these are just what we perceive of the localised fluctuations of fields (I know, it is counterintuitive, but more we learn about reality, more it becomes strange... ;-) )
@@PhysicsMadeEasybut sir there could be an one unified field and particles would be exitations in that one field with different frequencies and it would be easier to understand why there is need to make different fields and it rises question that what makes that fields different from each other
Work can also change the potential energy and kinetic energy of gas molecules when work is done on system gas compress how internal increase as potential energy of molecules decrease but kinetic energy is increased
Respected sir, what does energy per unit volume of electromagnetic wave intuitively mean....we derived energy per unit volume of electric field For AN SYSTEM(capacitor) WHERE E field is CONFINED....electric field is present in FINITE VOLUME AND UNIFORM BETWEEN CAPACITOR....but this quantity would not make sense if we have CHARGE ARRANGEMENT WHICH DOES NOT PRODUCE AN CONFINED E field...eg E field of an dipole.... similarly for magnetic field(inductor).... EVEN THEN WHY DO WE USE THIS STATIC FIELD ENERGY of these charge arrangement TO AN DYNAMIC EM WAVE ENERGY CALCULATION..I believe the energy of em wave comes from the source which tries to accelerate the charge, energy lost by source = energy of em wave...(am I correct?)....I am still unable to know why we static energy density of fields to calculate ENERGY OF EM WAVE...
Thanks you sir 🌟 your answers helped me a lot🙂
I am not super familiar Gowry with this type of calculation, but this is my two cents:
If you take a snapshot in time of the EM wave and focus on a single point, then I understand your concern, because E and M fields are not static (Like the E field in a capacitor).
EM waves, are dynamic but remember, they follow a symmetry (sine or cosine) that can be averaged. Therefore static equations should work out with minimal tweaking when calculating energy densities within the EM wave.
Check in your calculation if there no averaging somewhere versus space or time.
Maybe you can think of an analogy with electric circuits: When you calculate power of an AC (dynamic) circuit. I and V need to be 'rmsed' when you do so… The only difference is a simple factor of SQR(2) for I and V because of that symmetry. This operation is realised In order to make a comparison with the power generated with DC (static) circuit, and you can use the same formulas (DC: P = VI, AC: P = Vrms*Irms = VI/2).
Maybe this can help understanding why calculations of energy densities in dynamic sinusoidal fields leads to the same algebraic relations than for static fields?
Sir I have another question about the work, well I have asked about it earlier but sir not it's a bit different.
Sir consider a weightlifter who is lifting a weight of thousands of Newton, but the general formula says that the displacement is zero so the work done by the weightlifter on the object is also zero but sir after 2 or 3 minutes the weightlifter will feel very exhausted and tired and he will lose some of his chemical energy went?
We can relate it with our example also whenever we try to lift objects a compass for an hour refill very pain in a hands due to the loss of chemical energy so where does this energy went? Also I have one more question for the same as I have considered that we are lifting a box against the force of gravity so we have to apply some force so that the object can move at higher potential energy and when it reaches a certain height we stop lifting so the potential energy is also constant my question is that if the potential energy is constant then why we are feeling tired after sometimes lifting the box because it is constant it means that it has taken some certain amount of energy from our body and now it is in just same state then why we are continuously losing the energy?
Also I have another question and it is about light and fires,
Sir in usual campfire whenever we try to look through the fire we see objects but they are not still it seems that the light is bending and then coming one can say that the light is wobbling my question is that why it occurs?
Sir I have one more question, whenever the LPG cylinder gets exhausted we usually fill it with another help of a gas refill adaptor. My question on this is that whenever we try to fill an empty cylinder from another by putting the second one on the top of the cylinder and connected with a gas refill adaptor than the second one in which the LPG is transferred gets very cold?
images.app.goo.gl/kbCtLtzvvvZbu8s4A Why it is so?
Hi, so many question! And good ones!
1/ The weightlifter
The weightlifter does work... but not on the object he is holding above his head… This object will remain at the same potential energy, so now work is done on the object. What happens actually, is that in order to hold the object, his muscles need to develop a force (to counter gravity), and tense up. This tensing up generates a lot of heat (That’s why he is sweaty). The weightlifter is actually working on the molecules of air surrounding him speeding them up (the air around him increases in temperature). Same story with the other examples you gave.
You can also see it that way. Imagine a motor making a wheel rotate. Start the motor, but block the wheel with a solid piece of wood: the wheel is not turning, the motor doesn't do any work on the wheel. But the motor heats up…
2/ Light and Fire:
The fire eats up the air: the density of air changes around the fire. This creates a chaotic movement of the air from high density to low density regions. The refraction index of the air depends on its density, it is therefore fluctuating, bending the rays of light that go through that air. This is why things looked across the fire appear wobbly…
3/ LPG cylinder
When you fill an ‘empty’ LPG cylinder (container A) with the gas contained in another one (Container B), you are making the gas in B work against the remaining gas in container A: Gas B pushes the gas in A, and therefore the particles of gas B lose kinetic energy, in other words, the temperature of the gas lowers. This interpretation is within the ideal gas model (In that scope, if container A was truly empty (vacuum), gas B wouldn’t be pushing against nothing and remain a constant temperature.)
@@PhysicsMadeEasy thanks a lot Sir
Sir,Why does object fall towards the earth,is it because of potential energy or gravitational force? Please make video on this or comment the answer.
Hi Satyawati. they are both facets of the same thing: the effect of a gravitational field... If there is potential energy, there is always a force involved...
Your question reveals there is something you do not clearly get, maybe about forces. A Force is just a practical conceptual tool that was invented to reflect an acceleration (here in that case due to the conversion of energy of position (= potential energy) to energy of motion (Kinetic Energy). I invite you to check some of my videos that can help (What is Work, what is Energy and Why is gravitational potential energy negative). These could help clarify things in your head.
Just curious, is there a possibility of 2 different types of material have a different reaction to hot and cold? Meaning if you set 2 different objects on one another could there be a different outcome then equalizing? Just wondering if its a law it has to react that way in all circumstances. I'm sure time for it to equalize differs from object to object like steel to steel as steel to aluminum or copper. I was just wondering if it could make it completely opposite. I hope im making sense. I'm just new
Hi, what can differ with the types of materials is the rate of transfer of the heat (in other words, the time it takes for thermal equilibrium to be reached). factors that can intervene in that are for example the specific heat capacity and the conductivity of the materials.
On the other hand, the reverse process (the cold piece becoming colder while the hotter becomes hotter) is strictly forbidden by the second law of thermodynamics that implies that heat always 'flows' from hot to cold.
Does this answer your question?
@@PhysicsMadeEasy it does thank you. I kinda figured that was the out come but wanted to be sure. It would of been interesting to see if a material/atom had a different reaction. For instance if heated up the atoms reacted to heat in a very negative way by increasing the speed even when the heat is removed until it melted or exploded. One more question if you don't mind. Is there a max freezing point that can only be achieved? When you keep applying heat a object ends up melting. If you could freeze a object with no limit would the object shatter?
@@lovetolearn5253 Hey.
The shattering of an object when freezing comes from the speed at which you freeze it. If you decrease the temperature gradually, allowing the atoms to set themselves comfortably (a sufficient time for the materials stresses to get released), then, you can freeze it up to the lowest humans can freeze objects without anything noticeable happening on the macroscopic scale.
*Respected sir ,I have a question* .It would be really helpful if you could answer it for me . →What is the maximum theoretical limit possible temperature could we have in the universe .
As we all know that there is a lowest limit of possible temperature (-273°C)(If I AM not wrong here ) bcoz the movement of all molecule and particles almost STOP . the point to be noted here is that - temperature depends on the movement of particles.
Here, it seems that (motion/movement/ VELOCITY OF THE PARTICLES) is the contributing factor for deciding the limit
SIMILARLY ,if we perform a thought experiment on this Principle and set the value of PARTICLES upto OR almost to the "SPEED OF LIGHT". Bcoz as far as my knowledge is concerned Nothing can go Faster than light .
So from this can we tell that we can reach/Calculate the maximum theoretical temperature possible
Hi Adnan,
Intelligent question. But be careful… Temperature is not a measure of speed of particles but of their kinetic energy…
Kinetic energy also involves mass (1/2 * m * v^2). The maximum speed in our universe is the speed of massless particles (photons for example), referred to as speed of light.
Special theory of relativity mentions that when an object is provided kinetic energy, it speeds goes up, but also its mass…(When you run, your mass increases, even if it is by a micro-tiny amount!). When increasing the KE of an object, the work done is distributed between the speed of the object and its mass. When the speed approaches the speed of light, most of the KE comes from the mass of the object. not its speed.
So there is no real maximum theoretical temperature. Or you could say that the maximum temperature could be defined for an hypothetical massive particle that absorbed all the energy of the universe….
As a fun fact, the maximum temperature reached by man is 6 000 000 000 000 Kelvin (6 trilliion Kelvin). This is obtained by smashing two heavy ions moving close to the speed of light. Most of the Energy transferred by the accelerator as KE to these particles went into their mass before they smashed into each other
@@PhysicsMadeEasy ... thank you sir ...now I got it. Really Love your videos.you are one of the best teachers on TH-cam.plz keep up this amazing work. Thanks again.💖 From India
Please also explain latent heat in which temperature of system do not change and remain constant why ????
See my answer to your other question.
Respected sir🌟, consider we have an Stern gerlach DETECTOR oriented right to left , IF WE PASS AN SINGLE SPIN UP ELECTRON (detected UP by another detector) it would be either DEFLECTED RIGHT OR LEFT in our detector....IF WE DO NOT OBSERVE IT AND MAKE IT TO PASS THROUGH....EVEN THOUGH WE DO NOT OBSERVE....THE GERLACH DETECTOR WOULD EXPERIENCE AN NET FORCE OPPOSITE TO THE DEFLECTION DIRECTION OF ELECTRONS(Newton's law) RIGHT??
IS THAT AN MEASUREMENT???
DOES IT COLLAPSES THE WAVE FUNCTION???
Does gerlach DETECTOR always MEASURES while DETECTING??
what is the difference between detection and measurement.... Quantum mechanics?
Why detection does not collapse wave function but MEASUREMENT DOES ??
THANK YOU SIR 🌟
I don’t understand all the details of your question Gowri.
What is absolute though, is that once it is found out what the spin of the electron would be, the wavefunction has collapsed (or appears to have collapsed, I don’t believe in Copenhagen interpretation)…
In other words, as soon as any external entity in the environment has interacted with the electron, such as we can reconstruct / define the spin of the electron from the behavior of that entity, the measurement has been made, and the wave function has collapsed.
Sir I have a doubt related to the measurements of energy,
Sir we have taught that to measure the kinetic energy we can use the formula {1/2×mass×(velocity)²}, so in the case of kinetic energy or potential, it is clearly understandable that when a body is displacing with a definite velocity then it has certain energy.
But in the case of light energy, whose formula is given as (plank's constant×frequency) or {h×c/lamda},
if we consider a light bulb that is emitting red light , that it's energy would be around 3.06×10^-19 joules ( according to the above formula ).
Sir so my question is that, what is meant by this value, means if there is another red bulb with high intensity that how would the light energy related to intensity of light and time.
Because an average bulb has 10 watts, means it consume 10 joules/ sec, so what can we understand by that?
I am really confused that what can we understand by the formula of light energy.
Hi,
Your confusion comes from the fact that you are blending two radically different perspective on Physics:
The KE formula is related to Newtonian mechanics. Plank’s formula is related to quantum mechanics (QM), a revised version of physics developed in the beginning of the 20th century. Classical mechanics works well at the human scale, but breaks down when we go to a scale smaller than that of the atom, that’s why when humans started to look at tiny things, a quantum understanding of reality showed up!
In QM, light is made of photons. Plank’s formula gives you the energy of one single photon.
In your example, the 10 Watt bulb emits 10 joules per second of red light. A photon of red light according to your calculation, holds 3.06 x 10^-19J, so you can deduce that the bulb emits 10/3.06x10^-19 = 3.27x10^19 photons per second… Does this clarifies your understanding?
@@PhysicsMadeEasy again you clarified my doubt.
I am really obliged of you sir, your explanation is too good ,{(tha nk you)^Infinite} for this.
@@dspopnrendi1725 You are welcome :-)
so the temprature depends on the nature of what we are dealing with and its particules ?
Hi Flexn, temperature is a measure of the average kinetic energy of the particles (Kinetic theory approximation). When you provide heat to a material, increasing its Internal energy, some of it goes into potential energy of its particles, and the rest into kinetic energy of its particle. The structure of the material will define how this energy is shared between the two (the property that expresses this is its specific heat capacity).
So yes, how the temperature of a material changes when you heat it does depends on the material itself.
@@PhysicsMadeEasy thank you very much :D
Can you please give the solution this relativity paradox...an long train is move on an bridge with an gap(hole) in the track ahead... stationary observer sees train falling into the gap due to length contraction but in the train frame gap is very small so that train can easily pass by....??? What's wrong here???
Hi Gowri, The issue here is supposing that the train remains "rigid" in the frame of reference of the person on the train. The train will actually fall in the gap in both frame of references.
See this pdf link for more details: home.agh.edu.pl/~mariuszp/wfiis_stw/stw_rindler_lcp.pdf
Sir , work is mode of transfor of energy in mechanics is heat is also a mode of transfor of energy in thermodynamics at microscopic level. second question sir why we called heat is thermal energy .please answer
First question: Correct. Heat is the transfer of energy at the microscopic level (it is actually the sum of all works of individual particles).
Second question: Thermal energy is actually the kinetic energy contained in an object due to the motion of its particles (The kinetic part of internal energy), and this is what is transferred via heat.
I did cross some text books that refer to heat as being called thermal energy, maybe you have too. Maybe by abuse of language, this lack of rigor has spread...
@@PhysicsMadeEasy thank you sir
Sir if object A has thr temperature of 90 units and object B has the temperature of 10 units so,if they are touched by each other will object A loss temperature or object B gain temperature? Please answer.
Hi Astro. Both.
You have 4 apples, and give 1 to a friend. You lost one apple, and your fiends gained one... It's the same here (temperature represents average kinetic energy of particles, so if your system (A+B) is isolated, then conservation of energy applies).
Please note that you must also consider context: If one or both objects are in a phase transition, then the statement is only correct for total energy (Kinbetic + potential), not for temperature.
@Physics Made Easy Thank you so much sir I got a 98% in my exams because of you!
Well again I have a small doubt sir and that is about friction force. Sir does friction force depend on the pressure of the body?
I feel so because when we thought two bodies ,with same mass and on same surface, but the area in contact with the surface is different,
Then the one with less area in contact will have high pressure on the surface and that of the another one will be comparatively lesser, so the first one will interlock with the surface more nicely as compared to the second one then the friction should have increase in the first one but according to our standard formula it only depends on the normal reaction which is same in both. Is there any mistake in my thinking or something else?
Also there are many substance like tape which sticks easily on the surface, my question for this is that which force is responsible for this act?
Hi
I imagine two identical rectangular prisms, A and B, laying on the same surface (for example the same table). One (A) is laying on its larger area, and the other one (B) on its smaller area. You are wondering why the friction should be the same, because the pressure provided by B on the surface is larger than that of A, therefore, the imperfection at the interface are more interlocked with B. Did I understand your question well?
You are correct in saying that B exerts a higher pressure on the table and that in consequence the imperfections on table/B interface are more interlocked. the friction resulting from this will be larger for B than for A PER UNIT AREA.
A will be subjected to a friction lower than B per unit area, but it has a bigger area in total: if you sum this friction per unit area over the whole area for each individual prism, you will get the same total friction…
For your second question: All forces you experience in daily life are either of gravitational or electrical origin. For the cellar tape, it is electrostatic interactions between molecules that provide the force at the origin of the stickiness (This force is called Van Der Valls force).
I hope this helps!
@@PhysicsMadeEasy What can I say ? I am feeling very pleasurable. My doubt is clear. Thank you is nothing before you. 🙏🏿🙏🏿
Paaye laagu
Also I want to know more about the van der Waals force , so will you please explain it in your later videos.
@@PhysicsMadeEasy Also I have an another shilly shally, and that is about the gravitational force.
Well when we are talking about a black hole we talk about its density that is too much strong that even light can't escape from it. But if we consider a star that has same mass like that black hole but it's density is comparatively very low as compared to that of the black hole then it doesn't capture the light. so my question is that does the gravitational force anyhow link to the density of an object?
Because in the case of a black hole the light was not able to escape from its gravity but a star of same mass but very low density is not capable to trap the light with its gravitational pull, although both have the same mass and according to newton gravitational formula the gravitational force is only dependent upon the product of masses not even linked to the density of the object.
@@dspopnrendi1725 I am glad I clarified things. for you. Van der Walls forces... it's more relevant to chemistry but it is borderline to physics too, so why not. I'll put it on the list. Thanks for the suggestion.
@@dspopnrendi1725 You are forgetting that the gravitational force depends also on the distance between the object and the center of mass of the source of the gravitational field!
Take a large star of 10 solar masses (Like Betelgeuse), it’s radius is around a half a billion km. Take a black hole of the same mass: it’s radius would be of just a few tens of km. let’s say 30 km.
If a particle passes at less than 30k from the center of the black hole, it would not be able to get away. Now, what If that same particle passes at less 30 km from the center of mass of the star (it is actually inside the star), it would feel a force pulling it towards the center, but also a force pulling it outwards (by the matter located between itself and the external boundary of the star). Actually, the net gravitational force it experience would be quite small. And even zero, at the exact center of the star…
Respected sir,We calculate energy per unit volume of electric field of electromagnetic waves with
capacitor arrangement...I tried really hard to understand why do use, energy required to charge the capacitor and we divide by volume of capacitor to calculate energy per unit volume of electric field.... they say the energy is stored in electric field BUT the energy gained by an CHARGE Q in electric field depends on magnitude of Q; (ENERGY GAINED=Q×Electric field×Distance moved in E field;) then how can we predetermine the energy of
electric field per unit volume??(1/2)CV^2 and (1/2)Q^2/C...It's just the energy required to make the E
field in capacitor HOW CAN THIS BE EQUAL TO ENERGY GAINED BY AN CHARGE Q IN THAT FIELD?? CAN YOU EXPLAIN ENERGY PER UNIT VOLUME OF E AND B FIELD INTUITIVELY WHAT DO THEY MEAN??
Thank you sir
Hi Gowri,
Do not worry, your question shows that you have a good understanding. In physics there are often abuses of language for practical reasons. This is one of those.
The energy stored in a capacitor is equal to the work created to place the charges on the plates (done by a battery). This energy is the charge moved on the plates multiplied by the difference of potential energy per unit charge (i.e. potential difference) at the position of the two plates ( W = Q x DELTAV).
Let’s do a mind experiment. Disconnect the capacitor from the battery, and imagine you let a charge little q cross the gap between the plates. The charge q would follow the field line towards the negative plate and gain KE. At the same time, the potential difference between the plates would decrease because the charge difference between the plates would also have decreased: Some of the energy in the capacitor would have been converted to the KE of charge little q.
The abuse of language is to say that the energy is contained in the electric field, and not in the charges creating that field. On the other hand, it has a practical side to say so, because if you know the value of the energy (or energy density) of the field you do not have to care about the charges creating it.
I hope it helps!
Respected sir🌟🌟, During interference of EM wave... electric field adds up like vector....if two electric field of EM wave of same amplitude ,frequency,inphase...when added by vector gives,E+E= 2E, but when we add Energy of E field WHICH IS PROPORTIONAL TO E^2...it contradicts (€E^2=2€E^2)....
Similarly for distructive interference of two similar PLANE Em wave of PHASE DIFFERENCE of π interfering DESTRUCTIVELY COMPLETELY... IF E field becomes ZERO EVERY WHERE.....
WHERE DOES ITS ENERGY GO?what is wrong here?
Thank you sir 🌟
Think in average versus time. These vectors are dynamic (in an EM wave, the electric field strength vector changes becase it oscillates)... At a given point when there is a destructive interference, later at the same point there will be a constructive one. You can also average this in space. At one point where there is DI, there will be a CI at a point next to it…
I have a question, my dear professor. I understood that heat is a mechanical process, but what about infrared radiation?
Be careful otto, heat is a more of the sum of mechanical process: there are so many interactions between so many particles, that heat is better described as a statistical process. And actually, in text books heat is described as a 'non mechanical' transfer of energy (to emphasize its statistical nature opposed to a single mechanistic interaction).
Infrared radiation can be seen as light energy. IR radiation transports energy through space until it is absorbed. Usually it is absorbed by resonance by molecules that then jump to a higher vibrational and rotational energy level (understand they move more after absorbing the IR). In that case, the IR radiation increases the internal energy of molecules, providing the same effect as heating them.
@@PhysicsMadeEasy Thank you very much professor. My mind is too short to understand this phenomena at the level I would want. But your response helped me a lot.
I have question teacher
what is the difference between heat and kinetic energy
Kinetic energy = energy of motion of a specific system (a single particle, a car, a planet)
Heat: transfer of internal energy between two systems. Internal energy of a system = sum of potential energy and kinetic energy of all the particles of a system.