What Exactly IS a Cross Section pt. 1: Cross Sectional Area
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- čas přidán 27. 08. 2024
- Today I I break the world record of longest video explaining cross sectional areas. I spend a good deal of time deriving and giving geometric arguments for the equations most textbooks would simply define for the cross sectional area if one has a single target, or sheet of targets.
Pretty sure a cross section is when Babish cuts a sandwich in half and shows the camera but ok
Grad students:- Ah sh*t. The jackson.
Future grad students:- Ah sh*t. The dotson. :)
By the way
This is amazing. Looking forward to the next part.
I'm an undergrad so I don't know anything about this , but the way you explain things is addictive
thank you!
Exactly, i'm not even a physics major but this is so entertaining.
When you need to understand well cross sections for a close nuclear physics exam and Andrew reads your mind and upload a lesson.
What else? Thanks
I don't know if Im supposed to feel proud to even know this type of stuff.
- any physics student
14:54 NO SIR DON’T ERASE YET! I HAVEN’T FINISHED MY NOTES!
I like that as I progress through my undergrad, this type of video slowly starts to make more sense!
your hair screams physics.
?
I mean, you're not wrong!
it screams quarantine
Can do a video on the physics of a Flowbee. I think there's a lot we can learn here.
Andrew Dotson lmaoo
Andrew, i'm on my last semester at undergrad physics and i just got to know your channel! I appreciate how you keep your content funny without lowering the level of the jokes that require advanced physics knowledge to understand. You're really putting a smile on my face during this lockdown! Thanks!
I hope coronavirus will let me graduate one day
Your beard gets 40x larger each video. I aspire to be like you.
Awesome work as always!
I can feel how he's slowly descending into madness over the years of studying physics
bruv
In the next video, don't hold back on the math please!
His videos will hold back on views then.
Sahil, tbh it's not the case anyways that Dr. Andrew would want to attract high schoolers through arbitrary black holes like a certain other guy. I really don't think that his view count would stop him from presenting math in his videos. CZcams is probably not his long term ambition.
When I searched for cross sectional area looking for some explanatory video and find that Andrew have one doing so, bro thats happiness. Good video!
it would be a good exercise to estimate the average cross-sectional area of your beard
hold on let me measure the cross sectional area of the incident light first lol
The topic of cross section is worth a video and indeed more, since it's where theory meets experiment!
As such, it's not only a major player in high energy physics but it's also a fundamental in chemical kinetics.
It is? Can you refer me to some sources to read about that?
@@AgusMastex Hirschfelder et al., "The Molecular Theory of Gases and Liquids”, Wiley, (1964)
The analogy of the beam to the darts used in the Pi approximation was extremely intuitive and helpful. I'm about to start my undergrad so certainly a lot of this went over my head but that helped me grasp this topic. I love that way of approximating Pi, I recently wrote a program to do it in Java! Great video!
"The cross-section might be larger than the cross-sectional area of what you're hitting"
This is the most impressive idea I learned in this video. Thanks.
here to support my physics boi
:)
:(
You are like a big brother who is already doing what I wanna do and getting me ready for things to come.
Perfectly timed video, as always. I'm just listening to Nuclear and Elementary particles physics for the first time and those popped of immediately
OMG!!! thank you!!!!, I was just looking into cross sections, you saved my life!!. One quick question, how does this relate to probability of an interaction between small particles or atoms and how would you define a barn, Im still really confused in what does the barn unit mean
Thank you for making a mini series on this!! I’ve asked this question so many times, but it helps when many people explain it.
I cannot thank you enough for your video! It is so clear, deep, and kind all throughout!!! Can't wait to watch part 2!!!
Just this December I started a project on Cross section and now you have this. I'm so freaking excited dude! I'm looking for part 2 boi! Keep it going dude!
i m feeing happy to subscribed you...
I was always waiting for this type of video for understanding cross section
Currently trying to teach myself particle physics. So happy someone finally explained this whole cross-section idea that these other videos keep throwing around without much explanation.
This was incredibly helpful. I am doing a particle physics internship right now and was struggling a lot with this concept. Thank you!!!
Just started my grad program in nuclear engineering with only a background in chemical engineering... Thank you Andrew. This was definitely needed.
Omg I've made introductional videos about cross section too. But they're in Italian 🙈🙈❤
Great video and excellent analogies! I'd say that you can do Part 2 in a similar way to part 1 in the sense that you can maybe refer people who don't want to got through the math to various parts in the video. I'd go for the full on math approach with relevant links/references where needed. The concepts will still be there even if we can't follow the math from time to time.
Yeah I think that's what I'll end up doing
Most clearly described the idea behind the scattering cross section . Nice bro !
thanks a lot!
Wow. This video was definitely worth the wait Dr.Dotson!!
can't wait for part 2 !! keep up the great work andrew😊
Very nice explanation!
I had a jerk reaction to close the ad when the formula for dOmega appeared ^^
Go for the maths in the next one, but maybe sandwich the computations between beginning warning and summary, such that even if we don't get the details, we'll get the general ideas. As if we could "collapse" the development if not needed.
I really thought you would spend more time deriving stuff with dSigma/dOmega as we did in mechanics class and I remember being confused, but that's the difference between classes and videos, no exam to do at the end ^^
Yeah I wasn't sure how much I wanted to get into impact parameter stuff because, well, I never actually use it in any calculations. It's a very impractical variable to pretend to be able to control in nuclear/particle physics experiments from what I can tell.
I can see that this boi will become a physicist that everyone will bow down to
That's cool. Good to see derivations textbooks just omit.
This is so amazing thank you! Your explanation is incredibly easy to follow and very well presented! I hope some day you become a professor and I hope someday I can hear one of your lectures!!
For the next video don't hold back on the maths!
Great video, loved it. Always nice to recap cross section stuff :D
Looking forward to the next video, I will watch it tomorrow :D
Definitely go down the rabbit hole. We love to see insane level math.
The video I needed but not the one I deserved
Thank you this was very helpful! I recently got involved in particle physics research and there’s a lot I’m unfamiliar with, this topic being one of the biggest head scratchers
Dude I don’t know why but these videos are super motivating to study for the MCAT so thanks!
You are a good teacher sir, this is like dirty talk to me
Pls, go nuts with the details in your next video. In currently struggling with scatering in my QM course and i have an exam in a couple weeks. This video has already cleared a couple missconceptions i had, and im sure next one will be as helpful if not more. Thank you for such an amazing content :)
Such a good lesson, Andrew. Thanks.
thanks a lot for giving such an explanation. This and the tensor lectures are helping me greatly.
Hey first year undergrad here!
gr8 explaining you did there.
would like to see how the impact parameter relates to the differential cross-section in the next video
Pretty relaxing to have that as background while working
I know this is a bit stupid, but it would be great if you added the timestamps in the video description. Recently, CZcams started to show them (together with their names) in the video's "progress bar" if they appeared there.
This is legit because I JUST did a Monte Carlo scattering simulation!
do you play brawl stars?
@@sahilbaori9052 Hmm, that definitely follows from what I just said
Great video. I understood very little, but the way you explain is great!
This was really well-explained and really cool! Can't wait for the next video
Please both do a super-complicated version and also a simple version so both parts are happy. Because I really wanna see something complicated, but I'm not sure if I'd be able to follow...
Great video as usual. Please go down the rabbit hole for the next video. We need you at all guns blazing.
Great video!!! These videos are getting better and better
This would have helped so much in March while taking intro of engineering when I had to a volume flow rate lab and calculate the cross sectional area of bottles and pipes, my engineering professors was the typical engineering professor who just leaves you more confused when you ask for help...... I figured it out but man this would’ve helped
This was very informative (and a very good length so don’t worry about that)! You mentioned gold foil and talked about how objects don’t really hit each other; any chance you plan on going over the scattering of Rutherford‘s experiment? That was the one we talked about in my Modern Physics class and I always felt I was missing a few details.
Hey! I am a physics Undegrad and I'm trying to learn ForTRan. I love your videos, and in your PhD Vlog, you mentioned using FORTRAN. I think it will be GREAT if you could make a video on your work using fortran and maybe give a small tutorial, like you did with Python. HUGE REQUEST. Respect from India.
Thanks Andrew, you made my time storming the radio tower to take it back from team rocket much more educational
I am gonna pretend that is a perfect shadow of a ball if you let me pretend I know what you're talking about XD, but thanks for this cool video!
Bro, I found your content by accident and all I've being saying is "What." But still subscribed.
A Cross section is exactly what the Term says. It is the area That will scatter. If there is a probability going through without scattering the Cross section is smaller Then the Projected Disc - however Disc is something related with Short Range interaction. For coulomb Forces Cs can be big. Differential CS is Accounting for the propability beeing scatter to a certain angle (3d angle Element) . For Uniform scattering dcs=CS/4pi.
Andrew could you progess step by step mathematically and then do the heavy math stuff. Also could you point out the resources about how particle properties are found using particle accelerator
Visually this reminded me of how in the image of the black hole at the center of m81 we can only see the "shadow" of the black hole, the area encompassed by a schwarzschild radius, and is bigger than the black hole itself. But then again how else do you observe a black hole, when all that's emitted is light from the disk, jets or gravitational waves.
Your the best
Get a load of THIS guy
Perfect timing! Just starting my REU this summer this is will be helpful!
Oh where at?
Andrew Dotson Boston University, I was fortunate the program was able to transition online despite what is currently going on in the world right now.
Such a handsome physicist.. with incredible knowledge,,👏
Nice video! One question: what classical mechanics textbook should I pick up? I’m a high school senior (last year high school), but I alredy took calculus.
Next step would be a general physics textbook for first level classical mechanics (like high school physics, but maybe more calculus, depending on your high school) after that, for higher level but still undergrad, we used "Classical Dynamics of Particles and systems" by Marion and Thornton. You will need a bit more math than calc 1 for that, prerequisites are usually calc 1, 2, 3, and differential equations. But that doesn't mean you cant take a stab at it and learn as you go. Hopefully others will comment with better ideas.
Demtröder, Experimentalphysik 1 is a very good book imo, it's german though
Taylors classical mechanics is really good imo
May I please know your area of expertise? Cause a few days back I asked a question to a scientist at Fermilab but he said that he does particle physics...not nuclear physics😅
I don't want that to happen to you too whenever I ask you questions. BTW I am a 12th grader Science (Biology) student (that means I get Physics, Chemistry and Biology in my course + some side subjects) from India and I get this in my Physics course...just look at all the chapters (theory) for both class 11th and 12th, practicals are to be taught no more (quarantine times) + I get calculus too (just integrals and derivatives though and yeah...vectors too) [[[PDF LINK to all the chapters]]]
www.google.com/url?sa=t&source=web&rct=j&url=www.ncert.nic.in/rightside/links/pdf/syllabus/syllabus/desm_s_Physics.pdf&ved=2ahUKEwiYh7DgweTpAhWLILcAHc1dAD0QFjAAegQIChAB&usg=AOvVaw2alaME5CRRmAP4cHwYwJTk
Dude! Dude!
1:40 I think we are describing projection area this whole time.
As a mechanical major, I think cross sectional area is -- area that you get by cutting a body with some other surface (usually a plane). And most of my thermal physics, fluid dynamics, engineering drawing courses would agree with me here.
I don't care if I don't understand the math. I just want to watch another video by Andrew
I don't understand a word he's saying in any of his videos, but he's so freakin' handsome that I'm hooked.
Your videos make me wanna major for physics
edit: im a pure math guy
Do it.
Could you include bibliography in the description?
Great Video Andrew!
For the next one please don’t hold back on the math. Also would love if you talked about recoil mass techniques
I have no idea what you're talking about. But still watched the entire video.
Imperial Porter decanted into vessel? Check. First sip down me neck? Check. Ok, let's do this.
i was confused about scattering matrix in a course in quantum field theory , this seems promising
Very helpful video!
great work...really helpful ...
Im14 and your my idol ❤️❤️❤️❤️
you are
Hey Andrew, I know this isn't related but what LaTeX editor do you use? I'm trying to find one but I'm having a hard time.
There's a link in the description of this video of his: czcams.com/video/sIpj_D3VfzE/video.html
Or just go here:
www.wellesley.edu/lts/techsupport/latex/latexwin
The only CS tutorial I can understand
Hey what about Lorent invariant phase space any plan to make a video on that...if possible please mention that for cylindrical coordinator one also.
Thanks again for the great video
If you are doing any lecturing (like SI), could you record it? Sounds like that would a fun video
Excellent well tought out.
I have a question, maybe someone around or Andrew has an idea. You said in some long ago video something about "is going to be an experientialist" "is going to be a theorist". Now I fall very much into being really interested in theory when it comes to the courses and what I learning about. However I have found that I don't actually like sitting in front of a computer all day, I really miss my lab days, I make too many careless mistakes to compute things analytically. But I have almost only done theory courses in grad school because except of actually doing experiments, I really don't like experental courses. Now I need a master's thesis topic... And I don't know what to do. Where to go?
Good video Drew. Love you ~ Mom💕
Hi, thanks. It seems unclear how your N=Nb(1+t/tau) works, since N and Nb have different dimensions: 1/sm^3 and 1/sm^2 and you never assumed beam length to be 1 sm or so. Is there some secret or I get the idea wrong?
Where were you 3 months ago? 😭😭😭 haha Great explanation! Better to have it clear post-exam than never 😅
It was very helpfull sir
I love you sir💝💝💝
Even as a physics major, I still don't have a good understanding of something like cross sections.....I mean, I don't understand almost anything about physics and yet I'm doing this.....That's what life is.....Anyway, thanks Andrew.
Could you do a fundamentals of LaTex video. I started using it for my engineering classes but I would like to see how you use it and what do you recommend.
Please. Thank you
Can you do the derivation of the differential scattering cross section as a coordinate transformation from the impact parameter coordinates b, phi to the spherical coordinates theta, phi after scattering?
I started this video just for fun and ended up watching all thru it.
Basically, you tricked me into studying in this quarantine and i will never forgive you for that. Never.
me, an engineer: roadway plan go brrr
if u happen to give a lecture or 2 atleast u can be the only teacher in the world who doesnt say "Im not good at drawing, so bare with me"
29:28 you mentioned in the single target case that flux is (nvb)*(Ab)*(v), but in the case of multi-target 'Ab' is not a part of the flux. That is the only thing that confused me.
Can you explain that part?