Solutions to Problem 213 - Nuclear Energy

[@spectre4403]

As a 14 year old, Nuclear physics fascinates me and this is just beautiful

[@lecturesbywalterlewin.they9259]

super

[@fruityrazzmatazz9183]

Reading your comment makes me have faith in the future of humanity.

[@ANIMEWATCHER-kj8gc]

Same here as a 15 year old i love nuclear physics and i am trying to build a nuclear bomb. I prepared a model which i am gonna test on 2025 jan 5th

[@aswinganji7870]

@@ANIMEWATCHER-kj8gc Bro why is that on my birthday

[@unboxingking7832]

As a student of class X,I have always admired you from my childhood. Not going to say much more about you-sir, because we know what you have done to explain different topics.

[@PradyumnaBeheraGuda]

Hello dear friend where are u from ?

[@alemswazzu]

So glad you're still doing what you love. Helping the next generation.

[@מיכאלקונטרוביץ]

Thank You VERY much Dear Walter!! This is really very pleasingly surprising that you went on those topics which are not covered in your 3 series of the basic university physics courses that you lectured in the past at MIT. I'm really glad to the given opportunity of learning new topic and in particular this topic of nuclear physics. HUGE salut to You Dear Walter!!! Thank you!

[@8ballpoolproproplaying682]

Sir your explanation is wow... I can not find such type of explanation any where And love from india sir ❤❤❤

[@lecturesbywalterlewin.they9259]

I worked a whole week on my solutions which are really a complete lecture

[@Melki]

Thank you Walter for keep posting these blessings. God bless you

[@TanzuroAshitomash]

You are my favorite physics guru of all time sir i am sooo happy to watch your vedios

[@Ryuga756]

As a class 10 student physics amazes me.... And watching your strength and the love for physics just made me fall for it. Keep it up sir. Astrophysics is my favorite subject i wish i could study physics in higher levels when i grew up...

[@TharsanBA]

I am your fan sir and physics too I am jee aspirant I am interested in physics and I always wanted to feel physics

[@Worldofscience-n3h]

Hlo sir, I'm from india.. I love to watch ut videos sir.. And u r the inspiration for my students like me.. Actually I'm studying AS engineering sir..I would like to meet u sir.. How can i contact u sir??

[@riyapradhan7755]

I am a lot of fan of your teaching style. I must to be like you... For indian students❤

[@s.m.1354]

Hello professor, Three years ago I used my knowledge to use 1/3rd of the flux that is currently lost in shielding and moderation for the synthesis of C-14 using moderation in the cold neutron spectrum. C-14 when compressed into a diamond, sliced into slates and layered with nickel, can conduct beta radiation from decaying waste like cesium to produce a small current of energy. Good to see you educate kids but please never discuss the topic of breeding and tampering. Those two topics are classified. Good luck with your lessons!:)

[@SkyLightsUFOs]

Well I for one am happy that you are still alive. Friends are rare and special, do take care.

[@Umainahsadaf]

Thank you sir a lot i have been watching your videos since i am 13. You really inspired me in science. I'm indebted..

[@lecturesbywalterlewin.they9259]

Keep it up

[@AnshikaVerma-i2b]

Hello professor dear Lewin! Thankyou so much 🎉🎉 I am watching your video 2nd time This is a very knowledgeable & information I am UPSC spirant in hindi medium... My English is very bad But I intrested for your video Please sir writing for my preparation tips I watch frst time your video And got many information in your life experience........ that's is mindbloing and wonderful You are meet with Alakha Pandey sir....he is great man ......in India I am Indian...❤❤ Sir your are great in the world 🎉🎉 please take care & love my ideal teacher,,, thanks lot Thankyou being you,,, Love u sir 😘😘🎉🎉

[@Umainahsadaf]

Thank you sir❤❤​@@lecturesbywalterlewin.they9259

[@RickLambert963]

Thank you for your opinion, professor. I agree. Tesla also. Both were very great men who changed the world. That doesn't answer my questions, though. What value for energy? What value for mass? What value for the speed of light squared? Example of a value: The value of Pi is 3.142. The value of Phi is 1.618. My aha moment came about 35 years ago. I was reverse engineering a seal and was calculating density to identify the specific material at the time. The CEO son, who was in university for engineering at the time, walked past my office wearing a t-shirt that had E = mc^2 printed on it.

[@lecturesbywalterlewin.they9259]

E=mc^2 is universal - E and m have no limits, c is also universal as it is a constant throught our universe as far as we know.

[@RickLambert963]

​@lecturesbywalterlewin.they9259 I understand the equation professor. That still doesn't answer my questions sir. Let's try a third time please. What value for energy? What value for mass? What value for the speed of light squared? In the example: Energy is 15. Mass is 3. Light speed squared is 5. 15=3×5.

[@lecturesbywalterlewin.they9259]

@@RickLambert963 *your question is ill-defined* - if E is 15, what are the units. and if you know E, m follows bcoz E=mc^2 and c is always given

[@lecturesbywalterlewin.they9259]

@@RickLambert963 you are crazy E=mc^2 is reality. E is energy and mc^2 is also energy. Energy units on the left ofcoz must be the same as on the right. *I used SI units at first.* The nuclear bomb thrown in Hiroshima is *reality* wake up - take some courses in Physics - *this is my last msg*

[@GHOSTOFTHESHINIGAMI]

Thanks you sir because of you I learned how to imagine physics amd how to execute my imagination on paper. ❤

[@jenish-720]

Dear professor, does the perpetuum mobile behind you works for infinite time or for some years?

[@lecturesbywalterlewin.they9259]

it only works for about 300 years

[@RickLambert963]

​@@lecturesbywalterlewin.they9259E = mc^2 What value for energy? What value for mass? What value for the speed of light squared? The speed of light traveling through a vacuum may be expressed as: 186,282 miles per second. or 300,000 kilometers per second. or 983,571,056 feet per second. or 299,792,458 meters per second. "Today's scientists have substituted mathematics for experiments, and they wander off through equation after equation, and eventually build a structure which has no relation to reality." Nikola Tesla.

[@warfyaa6143]

Very useful, thank you very much.

[@khizirali]

I'm Near to finish your book For the love of physics❤ This is changing my life and converting my ancient enemy into best friend ⭐⭐⭐⭐⭐

[@gustavakerman2566]

“Physics works, and I’m still alive” is still going in the goddamn history books

[@mohsenrezaei5965]

Thank you, sir. I have a question: These questions, with their numbers, refer to what book or what list of questions, and where can I find them? I saw all of your mechanics playlists, and they are helpful.

[@lecturesbywalterlewin.they9259]

I made up this problem

[@markitsche987]

Thanks, Professor Lewin.

[@rafaelpadilla757]

Wonderful mini-lecture! 😊 As always!!!! Why not another on Art of the 3rd quarter of the 20th century? Sorry to bother you again with this Professor but I absorb art knowledge through your physicist's point of view waaay better than any other means. And your Art Quizzes add some bits and pieces but lack the general view of a lecture or a mini-lecture.

[@MuhammadNaeemAkhtar-x9e]

السلام علیکم! ورحمتہ اللّٰہ Respected sir iam from Pakistan and a physics teacher. Iam watching your lectures since 2016-17 and are helpful for me in teaching physics. sir the great please recommend me one of the best book that covers all your lectures.❤❤

[@lecturesbywalterlewin.they9259]

Feynman's famous books

[@MuhammadNaeemAkhtar-x9e]

@@lecturesbywalterlewin.they9259 Bundle of thanks respected sir 💞💞

[@ItsAnkush69]

But You Joined YT In 2024.

[@Udarshan8728]

You are always great sir ❤️ in the world 🌍, coming soon sir❤♥️🔥

[@Krushna10632]

Great Explanation Sir🎉🎉

[@yuganshigupta2299]

Hello sir your vdos facinates me till now❤

[@lecturesbywalterlewin.they9259]

Glad to hear that

[@okayzee2018]

sir please check this question out ------ Can the fundamental forces of nature (electromagnetic, weak, and strong nuclear forces) be unified under a single theoretical framework, and if so, what are the implications for our understanding of nuclear physics?

[@lecturesbywalterlewin.they9259]

they have not been unified yet. understanding nuclear physics will broaden your horizon substantially.

[@Luminousess]

Thankyou sir

[@DarthVader-ir1bx]

Usually they say that neutrons in nuclear reactors emitted through fission have to be slowed down to increase their capability or probability of inducing other fissions, but what about nuclear bombs, do they also require a moderator?

[@lecturesbywalterlewin.they9259]

nuclear bombs do not have a moderator as that would make the bomb too large and too heavy. Fermi built the very first nuclear reactor in 1942 in Chicago. *He used graphite as the moderator*

[@DarthVader-ir1bx]

@@lecturesbywalterlewin.they9259 Yeah, that's what I thought too, not to mention that adding a moderator will reduce the destructive power of the bomb because if the neutrons are slow there will be good chances for some chunks of the nuclear fuel to separate before they fission. Am I right?

[@SureshSuresh-oh9gc]

You is always a legend

[@TheSourav77]

Hi, Prof. Lewin! With the Physics Nobel being awarded to Neural Networks and AI, do you think classical and contemporary physics is slowly losing their significance for the award?

[@unboxingking7832]

Sir I have question what fascinates you more about space and what could be the reason when we put a glass piece in glass full of water that the glass piece is not visible.

[@lecturesbywalterlewin.they9259]

the light passing through the glass and the water will bend at similar angles due to their similar refractive indices, making the glass almost "invisible" to the naked eye; this phenomenon is called refraction

[@unboxingking7832]

@@lecturesbywalterlewin.they9259 Sir the way you explain everything is just astonishing,thanks.Hopefully I will get a chance in future to attend your lectures or meet you.

[@Just_dreaming_of_Success]

Hello sir our great physicst Walter Lewin, sir i know basic maths like: basic calculus, basic trignometry, i know how to solve quadratic equations,i.e. basic maths. Is that sufficient for physics?

[@jacobclassen5608]

Nuclear physics not for me. I try melt aluminum filings but the fuel doesn't get hot enough, because when aluminum oxide [aluminum powder] melts it gets smaller in mass. Therefore its a fission. When I get out the bath and I cannot rest my head because my hair is cold. Its not because my hair is wet but it is because my hair is now transferring energy into the air. As the air gets colder it gets more dense as the nucleus get close together. So its actually fusioned with dense cold. Every thing I see is now energy .

[@The_Green_Man_OAP]

If your powder loses mass, it may be because it's lost oxygen. Bond energy may be transformed to thermal energy of oxygen gas. In your second thought experiment, perhaps intramolecular bonds are formed as water molecules evaporate, leaving cooler ones behind that more easily bond together due to hydrogen & oxygen charge dipole alignments.

[@85481]

No

[@vyshnacv148]

Sir what's your thought about this year nobel prize in physics

[@lecturesbywalterlewin.they9259]

very cool

[@surendrakverma555]

Thanks Sir 👍

[@LEVINCENZO-f8z]

Hello sir glad to know that you're well Can you help me to know what shoud i do to study physics in abroad. Right know I'm a school pass out student searching for colleges

[@lecturesbywalterlewin.they9259]

apply to foreign schools - read their admission websires

[@overmasw8797]

dear professor ! 你好 ！！！

[@YuanLikeLi]

How can I find the exercise's text?😅

[@Ambar_Tomar_official]

🙏Sir I do not have high IQ but I work hard I want to become a scientist (medical Researcher) Is it possible? My teacher said to me you can't do anything in life you are dumb,etc🥺 I'm waiting for ur reply 🙏

[@lecturesbywalterlewin.they9259]

you have a bad teacher

[@LEVINCENZO-f8z]

Sir how can I study physics abroad please guide me for entrances It'll be huge help sir 🙏

[@lecturesbywalterlewin.they9259]

you have to apply - read their admission websites

[@RomanReigns-be9jj]

Can i request you professor, to dubb your mit 8.01 & 8.02 lectures in hindi ?? It can be beneficial for us. As dubbed in Arabic & Turkish is available so, hindi can be next one.

[@lecturesbywalterlewin.they9259]

go ahead - send me the dubb's version - I will then post it

[@Ashishsingh4098-l2e]

Thanks sir

[@lecturesbywalterlewin.they9259]

Welcome

[@hanslepoeter5167]

Niet eenvoudig. Het verhaal van de regelstaven in een reactor is een halve waarheid. Boor wordt gebruikt in het primaire koelmedium als moderator en de regelstaven zitten er normaal niet in. Kan ook niet anders want dan zou de bovenkant van de brandstofstaven niet opbranden en de onderkant wel. Als er iets aan de hand is vallen ze er onmiddelijk in natuurlijk. Misschien leuk om te weten is dat ze in borssele omhoog worden gehouden door elektromagneten. Valt de spanning weg dan vallen ze sowieso.

[@lecturesbywalterlewin.they9259]

Yes, all U-235 nuclear reactors utilize rods that absorb neutrons, typically called "control rods," to manage the rate of the nuclear chain reaction and control the power output of the reactor; this is a fundamental design feature of any nuclear reactor using U-235 as fuel.

[@hanslepoeter5167]

@@lecturesbywalterlewin.they9259 I agree, but as I explained it is used under scram or shutdown conditions. Managing the rate of chain reaction is done by boric acid in the primary coolant for high pressure reactors. if the rate of chain reaction would be controlled by the rods, the fuel rods would end up used on the bottom and unused at the top. That is not the case. Our new government is planning some more nuclear power plants. Borssele is the main foreseen location but Terneuzen and maybe Rotterdam are alternatives. By the time these are operational I'll probably have retired. I work in borssele a few months a year in the electronics. Thanks for the lecture. I'll try the next problem.

[@levikamado9608]

Still alive let's go

[@xyz34418]

Why an electron attact a proton?

[@lecturesbywalterlewin.they9259]

good question, use google

[@xyz34418]

Professor, is there any force exists to bend light? I mean invisibility

[@farhatunjum]

Sir iam preparing for iit jee but the electro dynamics is so boring and the mechanics part is soo interesting but why

[@kumaraakarsh3756]

Its about you. You find a subject interesting because you can grasp it easier than some other subject. Thats all!

[@GPSJhangi]

Hello sir i am crazy for you, please reply me 😢

[@meikejune4009]

Walter Lewin, my Love ❤, tell me is it possible to become a good Physicist if I eat one Quark every day? I eat it with self made blackberry marmalade.

[@lecturesbywalterlewin.they9259]

yessssss if you keep doing that long enough you may even get the Nobel Prize of Physics

[@meikejune4009]

​​@@lecturesbywalterlewin.they9259 Do you miss the Klompen Dance in your life in the US? I found it on KZbin It is so nice, especially the rule of the male klompen-dancer. kzbin.info/www/bejne/Z5nXoIJ9ga-DkK8si=WyLeLvJGhV-rXbub

[@darkomalic5950]

Hello walter! I really enjoy your physics lectures, but I must disagree with you on the last part of this one. I think everything will decay into iron, specifically irom ⁵⁶Fe, even if it takes an unimaginable amount of time (betwenn 10^1100 to 10^32000 years). This is beacuse any nuclear reaction which produces ⁵⁶Fe is spontantenous, and therefore will happen. The kinetics on the other hand, are so slow that we call many elements stable. You may call ⁴He stable (which, for almost all purposes, it really is), but given enough time, it will fuse to form ⁵⁶Fe. Therefore it is misguiding to say that many answers were wrong to say that everything turns into iron. Everything will, given a huge amount of time, many many times more than the age of our universe, turn into ⁵⁶Fe. The same principle applies in chemistry. You may call diamonds stable (beacuse they can exist for a really long time unchanged). But after a really, really long time, they WILL turn into graphite, because the reaction C(diamond) -> C(graphite) is (in most conditions) spontaenous. So, would you or would you not call diamonds "stable"? You do not specify spontaneity of the reaction and stability with relation to kinetics of the reaction, so to call answers which say that everything turns into ⁵⁶Fe wrong is not okay if you don't specify what you mean. P.S. this isn't meant to sound rude, it is just my take on the answer

[@lecturesbywalterlewin.they9259]

*I did mention that half lifes 100 longer (and even more) than the age of the Earth cannot be excluded - I even mentioned the derived half life of Telurium 128 (much longer than the age of the universe.)*

[@lecturesbywalterlewin.they9259]

times like 10^1100 to 10^32000 years are meaningless as the Earth will evaporate in about 5 billion years. For sure there will then still be helium and iron and carbon and many more so called "stable" elements. The universe is now about 8 billion (10^10) yr old and will not even exist anymore in 10^1100 yr. I respect what you wrote - but I already covered the basic idea in my lecture of what you wrote.

[@darkomalic5950]

​@@lecturesbywalterlewin.they9259 Thanks for acknowledging my answer! I will continue to try to solve more of your upcoming and previous questions. Your lectures are awesome!

[@MohitKumar-yg6ed]

sir your reference ID

[@lecturesbywalterlewin.they9259]

%%676**34$

[@clarke3481]

I warmly invite you to explore Islam's profound message of peace, unity, and harmony. Consider embracing its timeless teachings, which have brought purpose and guidance to millions

[@lecturesbywalterlewin.they9259]

I have explored Islam and decided to remain an atheist. Yet I respect your religion as well as many others.

[@Aizensosuke-d2l]

​@@lecturesbywalterlewin.they9259 nice reply sir. Absolutely neutral

[@ItsAnkush69]

Bruh We All Know What Are Radicals Doing In Paris