Physics Definition and 985 Threads

Hey, I was just contemplating career opportunities after my Undergrad. I am slightly interested in theoretical physics but I can't imagine doing it the rest of my life. My main interests are nano-photonics and quantum technologies and I am planning to do research in these fields. I am not...

Do the contractions affect physics in any frame? Examples: If length contraction reduces mass in the direction of motion, and therefore reduces the total momentum. (from observer's perspective) If in the reference frame of a station, the moving train weighs less than it did when parked...

I know that we can answer it using conservation of energy or using N's 2nd law. Using N's 2nd Law: ##F = mv \frac {dv}{dx}## ##Fdx = mvdv## For spring we have : ##F=-kx## ##(mg-kx)dx=mvdv## We'll get same result using above equation. My question: Average spring force from 0 to x is ##-\frac...

Hi. My story is weird and I need help. Brief backstory: I'm 21 and my brain is completely empty. As a kid, I didn't realize how interesting it was to do science and learn about anything, so I was weird. I'm the same way now. I can talk and talk endlessly about some unusual and difficult topic...

Hello, I am following the paper: https://www.yumpu.com/en/document/read/42212557/exact-exchange-in-density-functional-calculations and I am confused on page 14 where the generalized Kohn-Sham equations are derived. I follow that the ground state energy is The minimization of this step leads...

Hello! My name is Eleonora but you can call me Leo. I'm a girl. I love mathematics and physics and I aspire to become a theoretical physicist one day (or maybe this will change someday, but for now it's my biggest life goal). I still go to school. I want to self-study physics and find fellow...

I have never been sure how to round it according to the rules. My steps: ##\sqrt{5 \cdot 9.81 \cdot 0.10-\frac{1}{4\cdot \pi \cdot 8.85 \cdot 10^{-12}}\frac{(1.0\cdot 10^{-6})^2}{0.150\cdot 0.10}}## In [ ] is number of significant digits using multiplication/adding etc. rules. ##\sqrt{5 \cdot...

It would be interesting to build such a Bomb. "What kind of a Bomb? the Exploding kind!" Peter Sellers.

Force free: ##\mathbf{J} \times \mathbf{B} \sim (\nabla \times \mathbf{B}) \times \mathbf{B} = 0## (N.B. MHD applies so ##\epsilon_0|\partial \mathbf{E}/\partial t|/|\mathbf{J}| \ll 1##). Axisymmetric: can write ##\mathbf{B} = \nabla \psi \times \nabla \phi + B_{\phi} \mathbf{e}_{\phi}##...

I am a physics teacher. Teaching high school physics for more than two decades. I love to interact with colleagues who can share the variations made in the field of physics especially in the high school curriculum. The terms usually change and this effect the exams for students due to the use of...

Hello! Im a 25 years old italian student, currently master degree in quantum engineering. I decided to write in this forum one of my new ideas in physics. Im always very curious and mind open on new arguments!

I hold my identification card on a low-friction surface by one of its edges. I slightly lean it, and it starts to fall. Before it falls over, I place my finger against the card, and this prevents it from falling all the way over. Then, I withdraw my finger without pushing or pulling the card and...

Consider ##n## moles of a gas at a constant temperature ##T##. If we vary pressure ##P## and measure the corresponding values of volume ##V##, we can make a plot of ##P\frac{V}{n}=Pv## against ##P##. This gives us some graph which has some form. Turns out that for a range of pressure starting...

I'm a physics major at central washington university, and this forum looks like something I might be using from time to time :) nice to meet everyone!

Homework Statement: My question is how do you approach a new topic in Physics?, I'm starting grad school next semester and I think that I don't have the best routine studying Physics, so I wanted to know what are your best tips to learn something new in physics? Specially after the pandemic I...

Hey guys it would be great if you could take a look at my statement of purpose for a physics PhD program included below. The "Future Work" section at the end is where I talked about the specific program and faculties and how it will be a great fit for me. Any comments, criticism, advice is...

Several years ago I found your thread (now inactive) called "How can I get rid of air buildup in a syphon system". I am not a physicist, I am a tool and die maker and it really helped me get a better understanding of the problem and confirm what I was seeing. Since then, I have developed a...

Hi everyone, This will be a long post. I spent a few days mulling over what I wanted to say. I’m not sure I have thought of everything, but I covered a good body of what has gone through my mind, with any other details I’ll bring up as they pertain for any good Samaritan who can offer any...

Probably, my last question about isotropy. This is the last thing that I want to double check. We know that mathematically, passive and active transformation are both the same. In passive, coordinate frame is moved and nothing else, while in active frame, objects are moved and coordinate frame...

Yes... Can someone please explain the relativity theory to me in as much simple terms as possible. It's really way in over my head. Thanks.

Heads up, I'm Johnpaul. Came across this forum on Google. And really surprised that it has the exact name I needed. Thank God! I have a real interest in physics but I feel like I know nothing. Yeah the basic stuff such as electricity, Motions, Force, etc are there but the A-level physics is...

To estimate the concentration of fog droplets in the air, I thought of the mass of water in a given volume of air: I searched this value on the net, and I found that it is typically around ##0.05 g/m^3##. The mass of a single fog droplet can be calculated from its diameter and density. Assuming...

I'm pretty sure I understand why q^i u^j + u^i q^i is the stress component (i \neq j) of the Heat Flux Stress/Energy Tensor but I can't think of, or find any explanation for why q^i u^i + u^i q^i = 0. I found one reference in Lightman, Press, Price and Teukolsky - Problem Book in Relativity...

[Can skip everything blue] I have made a few threads in the past trying to get an informed perspective on whether sticking with Physics would be the best thing for me. Although, some of you have made very helpful comments, I am not sure if leaving Physics would be right path for me. I realize I...

During the night, I was traveling by local bus. And as I viewed through the window, the light from the street lights and the headlights of other vehicles appeared curved, as shown in the images below: One common answer is: because of refraction Is there any more explanation for this behavior?

This is going to be long, but I request you to read it completely. I finished my Bachelor's 1.5 years ago and it in 2022, I started studying, but I have been having issues with my family and I had to work part time while I was doing this. I had to care for my ailing grandparents and I many...

Hello Everyone, I am thrilled to join this esteemed Physics Forum, a space where the wonders of the universe are explored and discussed with fervor. Allow me to introduce myself as a dedicated aficionado of all things physics, driven by an insatiable curiosity to delve into the depths of this...

Torque_left = 100 kg * 1 m = 100 kg·m Torque_right = 200 kg * (13 - x) m = 200(13 - x) kg·m 100 kg·m = 200(13 - x) kg·m 100 = 200(13 - x) x = 12.5 meters pivot = 12.5 m

How the physics and science limit our cosmos observation and link it to speed of light? I could not find any equation, study or science that can support and limit our observation parameters.

The container and water inside it are at rest. ##F_{net,y}=ma_y## ##N - (m_{container}+m_{water})g = 0 ## ##N = (m_{container}+m_{water})g## ##m_{container}+m_{water}=700g## ##m_{container}+\rho_{water} V=700g## ##m_{container}+0.8(10*10*8)=700g## ##m_{container}=60g=0.06kg## Now we put a ball...

Hello! I can do this task just using this formula s=u*t+a*t^2/2. But just saw an example where someone used this Galileo toerem. Here is task: "An observer stands on the platform at the front edge of the first bogie of a stationary train. The train starts moving with uniform acceleration and...

Hi Folks. I've been retired for a decade. Waaaaay back in time (1980) I got an engineering degree; in other words, in the mid-70s I took three freshman physics courses: Laws of Motion; Electromagnetics; Relativity/Quantum Mechanics. I doubt that I remember anything at all from these classes...

I've seen this question in a textbook Calculate the following commutator [[AB,iℏ], A] I'm not to sure how you go about it i know [A,B] = AB-BA

In 1994 Frank J. Tipler wrote a book titled: "The Physics of Immortality" which appeared to suggest that physics and religion could be united. Absent religious or anti-religious prisms, if the universe were found to be closed (I know, it's not), is Tipler's physics worthy of serious consideration?

HI, I need help wtih my physics work and dont know where to ask

Hi all! Im gonna try to keep it short but as detailed as possible. First of all, sorry for my lower level english, possible misunderstandings of the physics Im talking about and misusage of the forum, Im not sure if vague threads like this is allowed at all. Please feel free to just answer...

I want YouTube channels that systematically raise my mathematics and physics level

Heyy Guys, I am Rohit Nair, SYBSC physics maths student from st. Xavier's College, Mumbai, India. I have a strong curiosity and thirst to learn and solve maths and physics problems. Currently working under a project on pulsars in TIFR, India's research institute. Also, I am into experimental...

This problem is a reformulation and solution of a problem posted earlier that did not go very far. A streamlined solution is posted here for future reference. The original post had an error which has now been fixed and the solution is, once more streamlined. See posts #4 and #5 for the...

Hello, you can call me V! I just got into highschool and am interested in physics, but I am super bad at math and science... I've been an english and art person my whole life so it's been tough LOL. I joined in the hopes that surrounding myself with STEM related stuff will have a positive...

I was here over 10yrs ago, at the time, I use LaTex. You still using that today or there's something new? I am encouraging my grand daughter to come to this forum as she's going to college soon. I don't want to tell her to learn the wrong thing as it's been over 10yrs already. Thanks Alan

Hello, I am Aiswarya Lakshmi S, from India. Currently, I am pursuing Masters in Physics. I am very much interested in exploring this subject. Looking forward for a great experience!

Hi all, Hope we have some electron beam evaporation specialists in the house. I'm working with an Telemark Electron Beam Source (Linear Multi-pocket and would like some help with the issues I am facing currently. I'm seeing blue light around both sides of the crucible when the e-beam is turned...

Hello I'd like to write my matura project on a topic of physics. But I can't really find a topic. I think I'd like to do something in the field of mechanics with reference to everyday life. The project requires an input of myself in this work, that means, i have to do something empirical and...

I do not understand enough.

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I am curious to understand how the universe works. I love to imagine if I were the universe or a particle why would I behave the way it does. It's a fun exercise. I am currently preparing for IIT JAM exam. I am glad to be part of this community. I am looking forward to getting to know you...

So excited to learn more about physics and to further my understanding! :partytime: This seems like a nice little corner of the internet. :]