Physics Forums: Science Discussion, Homework Help, ArticlesJoin Physics Forums, where students, scientists, and enthusiasts come together to explore and discuss the current understanding and practice of various scientific fields.Thu, 21 Mar 2024 08:58:08 +0000Thu, 21 Mar 2024 08:58:08 +0000Physics Forums: Science Discussion, Homework Help, Articles
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Easy ways you can support Physics ForumsThu, 21 Mar 2024 08:56:58 +0000
https://www.physicsforums.com/threads/easy-ways-you-can-support-physics-forums.813856/
813856invalid@example.com (Greg Bernhardt)Greg BernhardtWe are all members of an amazing community of science and math passionate people from all over the globe. However, "amazing" doesn't just happen over night or by itself. "Amazing" happens when members take pride and responsibility for the health of the community. It's like a tomato plant. The...
Read more]]>98Infinite momentum is impossible, boundary term in integration by partsThu, 21 Mar 2024 08:49:28 +0000
https://www.physicsforums.com/threads/infinite-momentum-is-impossible-boundary-term-in-integration-by-parts.1061055/
1061055invalid@example.com (George Keeling)George KeelingI am meeting the momentum space wave function ##\Phi\left(p,t\right)## in chapter 3 of Griffiths & Schroeter. I have an integral which I can integrate by parts:
Read more]]>10RIP Eric Carmen 1949-2024Thu, 21 Mar 2024 08:48:49 +0000
https://www.physicsforums.com/threads/rip-eric-carmen-1949-2024.1060889/
1060889invalid@example.com (pinball1970)pinball1970
https://www.theguardian.com/music/2024/mar/13/eric-carmen-obituary]]>4Supremum of a set, relations and orderThu, 21 Mar 2024 08:46:37 +0000
https://www.physicsforums.com/threads/supremum-of-a-set-relations-and-order.1061076/
1061076invalid@example.com (lys04)lys04Hello, found this proof online, I was wondering why they defined r_2=r_1-(r_1^2-2)/(r_1+2)? i understand the numerator, because if i did r_1^2-4 then there might be a chance that this becomes negative. But for the denominator, instead of plus 2, can i do plus 10 as well? or some other number...
Read more]]>1Wordle Lovers - Play the NYT Daily GameThu, 21 Mar 2024 08:44:56 +0000
https://www.physicsforums.com/threads/wordle-lovers-play-the-nyt-daily-game.1016903/
1016903invalid@example.com (fresh_42)fresh_42This thread is for all who like the daily Wordle game of the New York Times as much as I do.
The rules:
1) https://www.nytimes.com/games/wordle/index.html
2) Post your result.
3) Do not spoil the answer.]]>3758Derive trig equations 4, 5, and 6 from 1, 2, and 3Thu, 21 Mar 2024 08:41:23 +0000
https://www.physicsforums.com/threads/derive-trig-equations-4-5-and-6-from-1-2-and-3.924245/
924245invalid@example.com (jfnn)jfnn
Homework Statement
Hi again, I will re-write this on behalf of a request. I am struggling trying to derive these equations for a physics lab. The equations asked to derive are the equations that describe a perfectly elastic collision between objects of identical mass.
These are given...
Read more]]>10Proving the gravitational force of a solid sphere using integrationThu, 21 Mar 2024 08:34:45 +0000
https://www.physicsforums.com/threads/proving-the-gravitational-force-of-a-solid-sphere-using-integration.1061083/
1061083invalid@example.com (Sam Jelly)Sam Jelly
This is my attempt at the solution. x from the equation dF = GmdM/x^2 represents the distance between the circular plate’s center of mass and mass m.]]>5Contrapositive of theorem and issue with proofThu, 21 Mar 2024 08:27:57 +0000
https://www.physicsforums.com/threads/contrapositive-of-theorem-and-issue-with-proof.1061077/
1061077invalid@example.com (psie)psieConsider the following theorem:
Theorem Suppose that ##f:X\to Y## is a continuous map between two topological spaces ##X## and ##Y##. Then ##f(X)## is connected if ##X## is.
First, I don't know how to take the contrapositive of this statement. I'm not sure if the opening...
Read more]]>2ChatGPT Examples, Good and BadThu, 21 Mar 2024 08:21:20 +0000
https://www.physicsforums.com/threads/chatgpt-examples-good-and-bad.1048757/
1048757invalid@example.com (anorlunda)anorlundaI've been experimenting with ChatGPT. Some results are good, some very very bad. I think examples can help expose the properties of this AI. Maybe you can post some of your favorite examples and tell us what they reveal about the properties of this AI.
(I had problems with copy/paste of...
Read more]]>98Random Thoughts 7Thu, 21 Mar 2024 08:14:45 +0000
https://www.physicsforums.com/threads/random-thoughts-7.1056780/
1056780invalid@example.com (Evo)EvoTime to start a new thread.
Here is the last page of part 6.
https://www.physicsforums.com/threads/random-thoughts-part-6.875108/page-317#post-6960672]]>447Cantilevered and line-loaded steel beamThu, 21 Mar 2024 08:11:11 +0000
https://www.physicsforums.com/threads/cantilevered-and-line-loaded-steel-beam.1060989/
1060989invalid@example.com (Kalle)KalleI found the internal force Vxy 25 +6 =31kn. , bending moment Mmin -qb2/2 , M min- 14 kNm. delta =M/W I can't find Mmax and tau= V/As. So I need help to find Mmax and As wall area, how to find.]]>17is the power delivered by 1 no. of 3 phase systemThu, 21 Mar 2024 07:52:34 +0000
https://www.physicsforums.com/threads/is-the-power-delivered-by-1-no-of-3-phase-system.1061085/
1061085invalid@example.com (Jasper12)Jasper12
You
is the power delivered by 1 no. of 3 phase system equal to the power delivered by 3 nos. of 1 phase system? Assuming same voltages and amps ratings]]>0Escape Velocity of Earth starting from its CentreThu, 21 Mar 2024 07:50:54 +0000
https://www.physicsforums.com/threads/escape-velocity-of-earth-starting-from-its-centre.1061057/
1061057invalid@example.com (Priyo137)Priyo137What is the minimum velocity (theoretically) of an object located at the CENTER of the Earth to move it outside its gravitational field?]]>27Stress in cylinders due to thermal expansionThu, 21 Mar 2024 07:20:47 +0000
https://www.physicsforums.com/threads/stress-in-cylinders-due-to-thermal-expansion.1060528/
1060528invalid@example.com (ATT55)ATT55I have two concentric thick cylinders in close tolerance (currently 50 micron gap), with a thin layer of glue between them.
Internal cylinder is made from steel and external cylinder is made from ceramic (so the thermal expansion coefficient is not the same)
The assembly is headed form inside...
Read more]]>15Second order differential - Tanks in series cooling coilThu, 21 Mar 2024 07:17:25 +0000
https://www.physicsforums.com/threads/second-order-differential-tanks-in-series-cooling-coil.1060915/
1060915invalid@example.com (gmaverick2k)gmaverick2kI'm stuck on a problem:
T1 = dT2/dt + xT2 - y
T2 = (Ae^(-4.26t))+(Be^(-1.82t))+39.9
I'm unsure how to proceed]]>25Change in entropy of reversible isothermal processThu, 21 Mar 2024 07:02:24 +0000
https://www.physicsforums.com/threads/change-in-entropy-of-reversible-isothermal-process.1061027/
1061027invalid@example.com (Aurelius120)Aurelius120So I had to find change in entropy of system in reversible isothermal process.
$$T\Delta S_{sys.}=Q\implies \Delta S_{sys.}=nRln\left(\frac{V_2}{V_1}\right)$$
This was good because for isothermal process ##\Delta U=0\implies Q=W##
Read more]]>10I solved few questions on kinematics. Is my working correct?Thu, 21 Mar 2024 06:15:59 +0000
https://www.physicsforums.com/threads/i-solved-few-questions-on-kinematics-is-my-working-correct.828842/
828842invalid@example.com (Aichuk)Aichuk So the first question is:
A student standing on the platform of a railway station notices the first two carriages of an arriving train pass her in 2.0 s and the next two in 2.4 s. The train is decelerating uniformly. Each carriage is 20 m long. When the train stops, the student is opposite...
Read more]]>4Race car suspension ClassThu, 21 Mar 2024 06:15:16 +0000
https://www.physicsforums.com/threads/race-car-suspension-class.326355/
326355invalid@example.com (Ranger Mike)Ranger Mikereferences _ Paved Track Stock Car Technology by Steve Smith
Tune to Win by Carroll Smith
Software - Suspension Analyzer by Performance Trends
In order to understand the complexity of a Formula Cars suspension, a basic knowledge of the stock car suspension should first be mastered. When...
Read more]]>1690Electric field at the edge of half planesThu, 21 Mar 2024 05:47:40 +0000
https://www.physicsforums.com/threads/electric-field-at-the-edge-of-half-planes.1061051/
1061051invalid@example.com (Bling Fizikst)Bling FizikstI assumed the plate areas to be ##S## , then electric field at ##P## should be $$E_P=E_{+\sigma}-E_{-\sigma}=\frac{k\sigma S}{h^2}-\frac{k\sigma S}{(h+d)^2}\approx \frac{2k\sigma S d}{h^3}$$ but i think it's wrong here as ##P## lies at the edge , so it won't recieve electric fields in a way...
Read more]]>19Do I have a shot at top HEP-th programs?Thu, 21 Mar 2024 05:22:25 +0000
https://www.physicsforums.com/threads/do-i-have-a-shot-at-top-hep-th-programs.1061049/
1061049invalid@example.com (Laoki)LaokiI'm in my second year of undergrad at a top school and am seriously worried about my chances at grad school for HEP-th or HEP-ph.
I had pretty average/bad grades in my first year. I took classes lower than my actual level but got bored and unmotivated. I got mostly B's, a couple of A-'s, one A...
Read more]]>10Height of a balloonThu, 21 Mar 2024 05:17:08 +0000
https://www.physicsforums.com/threads/height-of-a-balloon.1061084/
1061084invalid@example.com (tremain74)tremain74ay = -9.8. Vy = -9.8 + v0*Sin0. y = -4.9*t^2 + v0*t*Sin0. By using formula of y, my solution was -4.9(10s)^2 + (10m/s)(10s)Sin0. I assumed that y was equal to 0. Since -4.9 is m/s^2 the answer would be -490m + 100m*Sin0. Therefore I assumeed Sin0 = 490/100.]]>3Neutron Star vs Black holeThu, 21 Mar 2024 04:34:27 +0000
https://www.physicsforums.com/threads/neutron-star-vs-black-hole.1060907/
1060907invalid@example.com (davLev)davLevIn the following article it is stated:
"We're seeing the gas whipping around just outside the neutron star's surface," said Edward Cackett (University of Michigan), in a press release. "And since the inner...
Read more]]>30Medical StudentThu, 21 Mar 2024 03:23:42 +0000
https://www.physicsforums.com/threads/medical-student.1061075/
1061075invalid@example.com (Create2028)Create2028Hello everyone]]>4Cover songs versus the original track, which ones are better?Thu, 21 Mar 2024 03:05:50 +0000
https://www.physicsforums.com/threads/cover-songs-versus-the-original-track-which-ones-are-better.1050205/
1050205invalid@example.com (pinball1970)pinball1970Which songs were performed, arranged or produced better in a cover than the original version?
Which songs should have been left well alone?
Also, I think restricting the covers just to released singles will restrict some interesting stonkers and stinkers so album tracks are allowed.]]>901Hoop rolling down a hillThu, 21 Mar 2024 03:03:13 +0000
https://www.physicsforums.com/threads/hoop-rolling-down-a-hill.1061082/
1061082invalid@example.com (lsie)lsieI've worked out how to derive the formulas for a solid cylinder and a solid sphere rolling down a hill.
E.g., for a cylinder:
Emech = KE + PE
mgh = 1/2 mv^2 + 1/2 Iw^2
gh = 1/2 v^2 + 1/2 (1/2r^2) v^2/r^2
gh = 3/4 v^2
v^2 = 4/3 gh
I then performed a derivative with respect to time and found a...
Read more]]>4U.S. Solar Eclipses - Oct. 14, 2023 (Annular) & Apr. 08, 2024 (Total)Thu, 21 Mar 2024 02:51:08 +0000
https://www.physicsforums.com/threads/u-s-solar-eclipses-oct-14-2023-annular-apr-08-2024-total.1051127/
1051127invalid@example.com (Borg)BorgThe 2017 total eclipse was awesome and we're going to get another opportunity at totality in the U.S in just over a year from now on Apr. 08, 2024. There will also be an annular eclipse on Oct. 14 this year. Time to start working on those travel plans before all of the hotels...
Read more]]>35Does anyone make zero-flicker computer monitors?Thu, 21 Mar 2024 02:11:44 +0000
https://www.physicsforums.com/threads/does-anyone-make-zero-flicker-computer-monitors.1060952/
1060952invalid@example.com (robengine)robengineAre any of the low-flicker monitors completely flicker free, not just low enough flicker to meet some low-flicker certification. Ideally I’m looking for something completely flicker-free like the LG EVO OLED TVs but smaller. I do not know all the terminology but some things I’ve been told to...
Read more]]>2How do I make Browserify work with Puppeteer?Thu, 21 Mar 2024 01:11:43 +0000
https://www.physicsforums.com/threads/how-do-i-make-browserify-work-with-puppeteer.1061081/
1061081invalid@example.com (Darkmisc)DarkmiscHi everyone
I am using Visual Studio Code with Node.js 18.17.1. I installed Puppeteer 22.5.0 with the following command:
Npm install browserify -g
I tried creating a bundle with the following command:
Browserify index.js -o bundle.js
This error message came up:
fs message:
Error: Can't walk...
Read more]]>0The inclined plane paradox (proved)Thu, 21 Mar 2024 00:54:52 +0000
https://www.physicsforums.com/threads/the-inclined-plane-paradox-proved.1061069/
1061069invalid@example.com (migyonne)migyonneHello, I invite you to watch this video.
This is a simple experiment, which has never been carried out and which proves that momentum can undergo a 'repartition'...
What do you think of this phenomenon ?
What conclusion can we draw from...
Read more]]>12Kitten Lovers: Cuteness OverloadWed, 20 Mar 2024 23:02:06 +0000
https://www.physicsforums.com/threads/kitten-lovers-cuteness-overload.130472/
130472invalid@example.com (Evo)EvoThis was just so damned cute, it deserved it's own thread.
Whenever I see cute kittens I can't help thinking of MIH, Tsu, Ivan, and Integral, and now Moonbear.
Moonbear, how's the kitty doing? We need an update!
This is quite the socially adept kitten, covering a yawn.
]]>3735Stokes' theorem in the planeWed, 20 Mar 2024 23:01:12 +0000
https://www.physicsforums.com/threads/stokes-theorem-in-the-plane.1061074/
1061074invalid@example.com (runinfang)runinfangThe question is a problem from Leithold's calculus book. I didn't understand the (x = 5 \cos(t)). Shouldn't it be (x = 2 cos(t))? I'm referring to item b.
i tried this way. i don't know what is wrong.
]]>1YouTube Classics, Part DeuxWed, 20 Mar 2024 22:42:41 +0000
https://www.physicsforums.com/threads/youtube-classics-part-deux.826985/
826985invalid@example.com (lisab)lisabA continuation of YouTube Classics.
Playing trombone to 'wildlife':
]]>717About nature of superposition of statesWed, 20 Mar 2024 22:39:17 +0000
https://www.physicsforums.com/threads/about-nature-of-superposition-of-states.1060603/
1060603invalid@example.com (HighPhy)HighPhyFor quantum mechanics, a certain property of a subatomic particle, e.g. the spin of an electron, which can be either up or down, is a "superposition of states," and one of the two conditions, e.g. the fact that it has spin up or down, doesn't manifest itself until the situation is...
Read more]]>119Calculate this Integral around the Circular Path using Green's TheoremWed, 20 Mar 2024 22:26:36 +0000
https://www.physicsforums.com/threads/calculate-this-integral-around-the-circular-path-using-greens-theorem.1061044/
1061044invalid@example.com (runinfang)runinfangIs my resolution correct? I can't identify.
Calculate the line integral ∮C(2ydx+3xdy), where C is the circle x2+y2=1, using the Green's Theorem.
Green's Theorem:
Let M and N be functions of two variables x and y, such that they have continuous first partial derivatives in an open disk B in...
Read more]]>3Galaxy recession and Universe expansionWed, 20 Mar 2024 22:23:35 +0000
https://www.physicsforums.com/threads/galaxy-recession-and-universe-expansion.1060849/
1060849invalid@example.com (cianfa72)cianfa72Hi,
I'm aware of the measured recession of the galaxies in our universe and the universe expansion itself cannot be understood as an "ordinary" velocity/speed (for instance in the FRW solutions of Einstein's equations).
Can you kindly help me clarify this topic ?
Thank you.]]>85Classifiers, threshold, and ROC curveWed, 20 Mar 2024 22:08:17 +0000
https://www.physicsforums.com/threads/classifiers-threshold-and-roc-curve.1061073/
1061073invalid@example.com (fog37)fog37Hello,
A classifier is a ML model that can classify between 2 or more classes. Some classifiers are called probabilistic in the sense that they output a probability score that is then compared against a threshold value (usually 0.5) to make the class decision. Other classifiers are not...
Read more]]>0Our Beautiful Universe - Photos and VideosWed, 20 Mar 2024 22:04:31 +0000
https://www.physicsforums.com/threads/our-beautiful-universe-photos-and-videos.800540/
800540invalid@example.com (DennisN)DennisNThis thread is dedicated to the beauty and awesomeness of our Universe. If you feel like it, please share video clips and photos (or nice animations) of space and objects in space in this thread. Your posts, clips and photos may by all means include scientific information; that does not make it...
Read more]]>2175Photographing a solar eclipse with a smartphone (safely)Wed, 20 Mar 2024 21:51:36 +0000
https://www.physicsforums.com/threads/photographing-a-solar-eclipse-with-a-smartphone-safely.1060765/
1060765invalid@example.com (Andy Resnick)Andy ResnickI've been getting a lot of questions (at work and home, etc.) about using a smartphone to photograph the eclipse. I don't own one, so I thought I'd check in the group here about 2 items:
1) I have been telling people if they place a (ISO 12312-2) solar viewer over the smartphone lens...
Read more]]>25Random PhotosWed, 20 Mar 2024 21:38:41 +0000
https://www.physicsforums.com/threads/random-photos.994801/
994801invalid@example.com (morrobay)morrobayA topic for random photos: Ko-Larn island 7 km West of Pattaya]]>1792Collection of Lame JokesWed, 20 Mar 2024 21:18:19 +0000
https://www.physicsforums.com/threads/collection-of-lame-jokes.25301/
25301invalid@example.com (quddusaliquddus)quddusaliquddusLamest joke you know ... :zzz:]]>18582Eye protection while watching a total solar eclipseWed, 20 Mar 2024 21:17:32 +0000
https://www.physicsforums.com/threads/eye-protection-while-watching-a-total-solar-eclipse.1060822/
1060822invalid@example.com (DrClaude)DrClaudeI got myself some glasses for the upcoming solar eclipse, but they are very dark! They work fine for looking at the Sun in all its glory, but I suspect I won't ne able to see anything of interest during the eclipse.
Does anyone have experience filtering out the harmful UV while still being...
Read more]]>33Isotopic exchange and SIMS diffusion profile measurementWed, 20 Mar 2024 21:15:19 +0000
https://www.physicsforums.com/threads/isotopic-exchange-and-sims-diffusion-profile-measurement.1061068/
1061068invalid@example.com (Dario56)Dario56Suppose there is a cylindrical (pellet) sample in the oxygen atmosphere as shown on the photo attached. Oxygen diffuses from the outside to the sample interior everywhere on the outer surface of the sample. From the photo, it can be seen that diffusion profile of oxygen is measured in the axial...
Read more]]>1Is My Sci-Fi Story's Scientific Premise Believable?Wed, 20 Mar 2024 20:00:55 +0000
https://www.physicsforums.com/threads/is-my-sci-fi-storys-scientific-premise-believable.1004340/
1004340invalid@example.com (unsaint32)unsaint32Summary:: Can you tell me if my sci-fi story's scientific premise is remotely believable?
I am writing a sci-Fi novel. The scientific premise of the story is like this...
The creature in my story is created in a lab by a quantum physicist. With a quantum computer, and electron...
Read more]]>17Waste Container Handling Crane -- Why are we getting this lift offset?Wed, 20 Mar 2024 19:54:13 +0000
https://www.physicsforums.com/threads/waste-container-handling-crane-why-are-we-getting-this-lift-offset.1060660/
1060660invalid@example.com (AlanThomas)AlanThomasI am dealing with a waste container handling crane. Waste container is 12000kg. It is lifted by a grapple by twist locks at each corner. Height of lift is 14m. The contents of the container leads to an offset c of g which cannot be avoided. The containers are to be stacked 6 high.
The crane...
Read more]]>12Logical representation of prime numbersWed, 20 Mar 2024 19:45:56 +0000
https://www.physicsforums.com/threads/logical-representation-of-prime-numbers.1060706/
1060706invalid@example.com (lys04)lys04One of the discussion questions for my class this week was to express the condition "p is a prime number" using formal logic.
The answer my uni's got is (∀d∈N)[(d>=1∧p≠1)∧(d|p⇒((d=1)∨(d=p))]. My interpretation of this is all the natural number d that (satisfy d>=1 and prime number is not equal...
Read more]]>15Electron motion on axis of a charged ringWed, 20 Mar 2024 19:40:17 +0000
https://www.physicsforums.com/threads/electron-motion-on-axis-of-a-charged-ring.1061045/
1061045invalid@example.com (Ben2)Ben2Showing the motion is simple harmonic seems routine. The 5th equation on p. 674 gives ##E=frac{1}{4\pi\epsilon_0}frac{qx}{(a^2)+(x^2)}^frac{3}{2}##, but matching expressions for ##\omega=k/m## yields only ##x=frac{ea^2}{2}##. Something in the model is escaping me. Thanks for any help offered!]]>7Two Celestial Bodies in Orbit (Centripetal & Gravitational Forces)Wed, 20 Mar 2024 19:26:39 +0000
https://www.physicsforums.com/threads/two-celestial-bodies-in-orbit-centripetal-gravitational-forces.1061070/
1061070invalid@example.com (amandela)amandelaSo I did set the two above equations equal for the solution. But is that not in effect ignoring one of the m's in the orbital motion? I feel like it should be F_c = 2ma. How should I think about it?
Thank you.
]]>2Studying Maths at UniWed, 20 Mar 2024 19:23:06 +0000
https://www.physicsforums.com/threads/studying-maths-at-uni.1061005/
1061005invalid@example.com (ParentUK)ParentUKHi all.
I'm looking for some insight from parents/teachers/uni lecturers about predictors that might indicate a student is talented enough to do a Maths degree and excel at it. My little girl is now in year 10 and about to do her GCSEs next year and is trying to figure out what she wants to do...
Read more]]>8Weird News CompilationWed, 20 Mar 2024 19:14:39 +0000
https://www.physicsforums.com/threads/weird-news-compilation.878428/
878428invalid@example.com (Evo)EvoI'm always finding weird things in the news and thought it might be fun if we all shared odd stories we came across. Please feel free to post odd, funny or unusual stories in this thread.
Turns out that Zoobyshoe beat me in posting about this in another thread, so he will officially be known...
Read more]]>1695Operators On Multivariable Wave FunctionsWed, 20 Mar 2024 19:03:20 +0000
https://www.physicsforums.com/threads/operators-on-multivariable-wave-functions.1061071/
1061071invalid@example.com (flyusx)flyusxI know the way to solve the first part is to find <ψ|Αψ> and compare it with <ψΑ|ψ>. This comparison can be done through an integral representation where we take ψ* and act A on ψ to be the integrand, or act A on ψ* and multiply by ψ for the integrand. If the integrals are the same, then the...
Read more]]>0[Griffiths Electrodynamics] Finding the electric flux through this quarter cylinderWed, 20 Mar 2024 17:15:35 +0000
https://www.physicsforums.com/threads/griffiths-electrodynamics-finding-the-electric-flux-through-this-quarter-cylinder.1061006/
1061006invalid@example.com (physics_student01)physics_student01TL;DR Summary: Confusion in φ cap direction for Left & Back face
The image of the question is shared at this Imgur link - The only issue I'm facing in this particular problem is in calculating the flux through the "Left" & "Back" faces of this quarter cylinder.
More...
Read more]]>9Can Earth or any spherical object in space act as a particle collider?Wed, 20 Mar 2024 16:53:59 +0000
https://www.physicsforums.com/threads/can-earth-or-any-spherical-object-in-space-act-as-a-particle-collider.1061067/
1061067invalid@example.com (adhd_wonderer)adhd_wondererThis is most probably a dumb idea as I'm far from deep physics knowledge but I was thinking.
What if Earth is hot inside not because of the pressure and the radioactivity but because it's mass attracts particles (similarly to gravitational lensing) and they collide right in the Earth's center?]]>2Who am I?Wed, 20 Mar 2024 16:18:54 +0000
https://www.physicsforums.com/threads/who-am-i.1061041/
1061041invalid@example.com (Seth_Genigma)Seth_GenigmaI would like to be called Seth Genigma, you can use nicknames I don't mind if you choose to. I am a student in Waitaki boys high school and I love all sciences. I learn easily and am interested in a lot of things.]]>2IntroWed, 20 Mar 2024 16:16:23 +0000
https://www.physicsforums.com/threads/intro.1061050/
1061050invalid@example.com (Laoki)LaokiHi, I'm currently a second-year undergrad from the US perpetually stressed about grad apps. I'm interested in high energy theory and phenomenology.]]>2Seeking a platform to discuss physicsWed, 20 Mar 2024 16:14:37 +0000
https://www.physicsforums.com/threads/seeking-a-platform-to-discuss-physics.1061056/
1061056invalid@example.com (Priyo137)Priyo137As a physics enthusiast high-school student, I often run into troubles engaging with physics problems. In PF, I am going to seek a place for physics discussions. Thanks.]]>2Hello everyoneWed, 20 Mar 2024 16:13:12 +0000
https://www.physicsforums.com/threads/hello-everyone.1061054/
1061054invalid@example.com (MrAndrew)MrAndrewHello everyone,
I heard about PF from Reddit. I'm a mechanical engineering enthusiast and looking forward to engaging with everyone here!]]>2Functional Analysis for Physics in 2024Wed, 20 Mar 2024 15:52:24 +0000
https://www.physicsforums.com/threads/functional-analysis-for-physics-in-2024.1061058/
1061058invalid@example.com (psterphysics)psterphysicsPhysicists provided the motivation for studying functional analysis (FA) 100 years ago. But is an in depth understanding of FA necessary in 2024? A slightly different way of putting it would be: is there any important work being done by physicists that requires working knowledge of all the...
Read more]]>7Doppler and Searchlight (Headlight)Wed, 20 Mar 2024 15:49:12 +0000
https://www.physicsforums.com/threads/doppler-and-searchlight-headlight.1061003/
1061003invalid@example.com (Albertgauss)AlbertgaussThe images below were taken from the website
Read more]]>21Share Animal Pictures: For Animal LoversWed, 20 Mar 2024 15:39:27 +0000
https://www.physicsforums.com/threads/share-animal-pictures-for-animal-lovers.583729/
583729invalid@example.com (micromass)micromassPost your favorite animal pictures here!]]>2665Collection of Science Jokes P2Wed, 20 Mar 2024 14:53:11 +0000
https://www.physicsforums.com/threads/collection-of-science-jokes-p2.847743/
847743invalid@example.com (Greg Bernhardt)Greg BernhardtOld thread: https://www.physicsforums.com/threads/science-jokes.4463/page-44
My wife just drew this
]]>3371Experiment on the variation of weight with temperatureWed, 20 Mar 2024 14:49:15 +0000
https://www.physicsforums.com/threads/experiment-on-the-variation-of-weight-with-temperature.1060797/
1060797invalid@example.com (MartinG)MartinGHello !
According to what I have read on the internet, the weight of a body varies with temperature, its mass remaining unchanged according to the theory of relativity.
My question is what experiment is done to corroborate that the weight of a body increases with the increase in its...
Read more]]>20Loss of gaseous volume because of fuel combustionWed, 20 Mar 2024 14:43:52 +0000
https://www.physicsforums.com/threads/loss-of-gaseous-volume-because-of-fuel-combustion.1061053/
1061053invalid@example.com (Zardo)ZardoHi,
1st and general case:
2 H2 and 1 O2 take up 1 liter of volume at, for example, 20°C, before combustion. After combustion and cooling down to 20°C, how much volume do the exhaust gases take up?
Since the stoichiometric relationsship is 2 mols of H2 for every mole of O2, so those...
Read more]]>2How to select a pump for a venturi injector?Wed, 20 Mar 2024 14:42:33 +0000
https://www.physicsforums.com/threads/how-to-select-a-pump-for-a-venturi-injector.1061065/
1061065invalid@example.com (Saut Renato)Saut RenatoI'm building a fertigation system using 1 inch venturi injector with ball valve at the end to simulate drip irrigation system pressure requirement. i have read to start an injection you need 30% pressure difference between injector inlet and outlet. the pressure I'm simulating is around 10 meter...
Read more]]>0New cosmological neutrino mass constraint: sum<0.09 eV at 95% CLWed, 20 Mar 2024 14:40:52 +0000
https://www.physicsforums.com/threads/new-cosmological-neutrino-mass-constraint-sum-0-09-ev-at-95-cl.1005042/
1005042invalid@example.com (mfb)mfbarXiv: On the most constraining cosmological neutrino mass bounds
From neutrino mixing we know that an inverted order (two "heavy" neutrinos, one light neutrino) needs a sum of masses of at least ~0.09 eV, while the normal order (two light, one "heavy") can have a sum as low as ~0.05 eV...
Read more]]>6Why does my ceiling glow in the dark?Wed, 20 Mar 2024 14:34:06 +0000
https://www.physicsforums.com/threads/why-does-my-ceiling-glow-in-the-dark.1061034/
1061034invalid@example.com (fro2g)fro2gCan you explain this for my grandmother?
Four years ago I rented an apartment for her on the 7th floor in a new building. I then decided to take care of my grandmother, so I lived with her. Everything was fine, but a year later the light bulb in the guest bathroom burned out. Since I'm the...
Read more]]>11Who is your favorite Jazz musician and what is your favorite song?Wed, 20 Mar 2024 14:20:14 +0000
https://www.physicsforums.com/threads/who-is-your-favorite-jazz-musician-and-what-is-your-favorite-song.1051251/
1051251invalid@example.com (BadgerBadger92)BadgerBadger92I have always liked Jazz music (and blues, electric blues to be particular)
Who is your favorite musician and song?
I’ve always liked Herbie Hancock, especially his song “Maiden Voyage.”
]]>0What ever happened to Classical Unified Field Theory?Wed, 20 Mar 2024 13:41:49 +0000
https://www.physicsforums.com/threads/what-ever-happened-to-classical-unified-field-theory.1061062/
1061062invalid@example.com (Rick16)Rick16Are there currently professional physicists who work on Einstein’s quest to unify the gravitational field and the electromagnetic field (as classical fields), or has this idea been completely abandoned? Is it simply a hopeless endeavour?]]>0Displacement operation acting on individual quadrature componentsWed, 20 Mar 2024 12:13:21 +0000
https://www.physicsforums.com/threads/displacement-operation-acting-on-individual-quadrature-components.1061015/
1061015invalid@example.com (waadles)waadlesHi all,
I have a naive understanding of how operators work and wondered if someone could help me. I have tried to understand this myself, but alas, I think my knowledge is too premature to understand what I am reading online. Is someone able to explain?
I want to perform the operation...
Read more]]>3Double experiment: "Falling ball viscometry" and viscous flow in an horizontal pipeWed, 20 Mar 2024 11:26:08 +0000
https://www.physicsforums.com/threads/double-experiment-falling-ball-viscometry-and-viscous-flow-in-an-horizontal-pipe.1058683/
1058683invalid@example.com (HighPhy)HighPhyTL;DR Summary: Analyze, with the help of @Chestermiller, the importance of viscous interactions in a vertical geometry ("Falling ball viscometry") and in an horizontal viscous flow.
The following double experiment was conducted by me a few weeks ago. @Chestermiller and I discussed...
Read more]]>28Rotations on the Bloch sphereWed, 20 Mar 2024 10:31:37 +0000
https://www.physicsforums.com/threads/rotations-on-the-bloch-sphere.1061047/
1061047invalid@example.com (kelly0303)kelly0303Hello! I am curious about how different rotations on the Bloch sphere are done in practice. For example, assuming we start in the lower energy state of the z-axis (call it |0>), a resonant rotation on the Bloch sphere by ##\pi/2## around the x-axis will take you to ##\frac{|0>-i|1>}{\sqrt{2}}##...
Read more]]>1Work energy theorem problem -- Block sliding up a curved inclineWed, 20 Mar 2024 09:12:29 +0000
https://www.physicsforums.com/threads/work-energy-theorem-problem-block-sliding-up-a-curved-incline.1061046/
1061046invalid@example.com (tellmesomething)tellmesomething
I did: Work done by gravity+work done by applied force= KE(final)- KE(initial)
Work done by gravity should simply be -mgh
=100*5=-500J
For work done by applied force we know:
W=∫F⋅ds
which can also be written as
W=∫Fdscos(θ)
since F is constant i can take that out
W=Fcos(θ)∫ds
here...
Read more]]>10Eddy Current DampersWed, 20 Mar 2024 08:51:06 +0000
https://www.physicsforums.com/threads/eddy-current-dampers.1061040/
1061040invalid@example.com (Juanda)JuandaThis post is somewhat of a continuation of this other post. I would like to better understand induction and be able to link the electrical equations with Newton's.
For reference, this is a paper about the Eddy Current Damper I would like to study first.
I think these components are...
Read more]]>3Why isn't there an effort to name non-stellar celestial objects?Wed, 20 Mar 2024 07:56:14 +0000
https://www.physicsforums.com/threads/why-isnt-there-an-effort-to-name-non-stellar-celestial-objects.1048995/
1048995invalid@example.com (Nathi ORea)Nathi OReaI find it kind of strange that some of the brightest star clusters (and probably other things too), do not have official names or seemingly no names at all.
For instance there are 3 really bright clusters around the Carina Nebula:
- NGC 3532: Which seems to be called a bunch of different...
Read more]]>21A question from a paper on perturbation theoryWed, 20 Mar 2024 07:35:19 +0000
https://www.physicsforums.com/threads/a-question-from-a-paper-on-perturbation-theory.1061052/
1061052invalid@example.com (Safinaz)SafinazWhere ##\delta \phi## is the first-order perturbation of a scalar field, ##\Phi## is the first-order perturbation of the space-time metric, and ##H## is the universe’s scale factor. It’s mentioned that this relation is given in reference:
Read more]]>0Are all biological catabolic reactions exergonic?Wed, 20 Mar 2024 07:07:23 +0000
https://www.physicsforums.com/threads/are-all-biological-catabolic-reactions-exergonic.1060796/
1060796invalid@example.com (mktsgm)mktsgmGenerally it is said that all biological catabolic reactions are exergonic. Famous example is ATP hydrolysis is exergonic. That's why it is called energy currency. Similarly breaking of glucose molecule into pyruvate also releases energy to form ATP.
But in chemistry it is said that breaking of...
Read more]]>8Is this a valid representation of a derivative?Wed, 20 Mar 2024 06:12:46 +0000
https://www.physicsforums.com/threads/is-this-a-valid-representation-of-a-derivative.1061042/
1061042invalid@example.com (docnet)docnetIf ##f(g(x)) =f(x+h)##, then ## \lim_{h\to 0} \frac{f(g(x))-f(x)}{h}= \lim_{h\to 0} \frac{f(x+h)-f(x)}{h}=f'(x) ##.
What if we let ##g(x) = x+\sin(h)##?
Then ## \lim_{h\to 0} \frac{f(g(x))-f(x)}{h}= \lim_{h\to 0} \frac{f(x+\sin(h))-f(x)}{h}##
This is not equivalent to that the standard...
Read more]]>12Higher Chance to get Lightning Strike by Large Power Consumption?Wed, 20 Mar 2024 06:10:53 +0000
https://www.physicsforums.com/threads/higher-chance-to-get-lightning-strike-by-large-power-consumption.1061048/
1061048invalid@example.com (physicsdick)physicsdickAssume there are two tall building with same height, and the materials are the same, having same distance away from the storm cloud.
Will the one building with extreme high consumption of electricity cause higher chance to get struck by lightning than the one building without ?
Thanks!]]>1Computer Communication Theory & Information Theory - A name change?Wed, 20 Mar 2024 02:51:02 +0000
https://www.physicsforums.com/threads/computer-communication-theory-information-theory-a-name-change.1061035/
1061035invalid@example.com (Lou Arnold)Lou ArnoldRetired computer engineer here. I have a professor's unpublished notes, back to 1974 entitled "Computer Communication Theory" that containing a great deal of probability, random variables, and Markov chain sections as well as old Bell Systems Journal notes about hardware and protocols. Has this...
Read more]]>3For a translating block with slipping find the maximum force FWed, 20 Mar 2024 02:40:06 +0000
https://www.physicsforums.com/threads/for-a-translating-block-with-slipping-find-the-maximum-force-f.1061043/
1061043invalid@example.com (annamal)annamalFor this translating block problem, below is the solution. I was wondering why if I took the moment about the center of gravity G, the answer for F would no longer be the same because ##I_G \alpha = -\mu_k N (h/2) + N (b/2) - F*d = 0## because ##\alpha = 0##
$$F = \frac{-\mu_k mg (h/2) +...
Read more]]>2Einstein - de Haas EffectWed, 20 Mar 2024 01:51:46 +0000
https://www.physicsforums.com/threads/einstein-de-haas-effect.1060770/
1060770invalid@example.com (Swamp Thing)Swamp ThingThis effect is (apparently) always explained in terms of a "book-keeping" need to conserve angular momentum. I totally get that (as the kids say these days), but it doesn't provide a chain of cause and effect that leads to the observed rotation of the iron rod.
Is there a classical...
Read more]]>20How do equivalent ratios work in practical terms?Wed, 20 Mar 2024 01:35:20 +0000
https://www.physicsforums.com/threads/how-do-equivalent-ratios-work-in-practical-terms.1061032/
1061032invalid@example.com (SHASHWAT PRATAP SING)SHASHWAT PRATAP SINGmy doubt is that let's say we have a ratio 5:10 now the equivalent ratio for this would be 1:2 but what I am not able to understand is - let's say we have a situation in which it is given that the ratio of girls to boys is 5:10 which means for every 5 girls we have 10 boys but if we see the...
Read more]]>19What kind of technology will be available in a million years from now?Wed, 20 Mar 2024 00:36:44 +0000
https://www.physicsforums.com/threads/what-kind-of-technology-will-be-available-in-a-million-years-from-now.1057172/
1057172invalid@example.com (Uri Zlatnik)Uri ZlatnikWhat kind of technology will be available in a million years from now? Is the world going to be a better place in a million years from today?
Will it be possible to solve chess or have completely self-driving cars and self-driving trucks in a million years from now?]]>60Iceland warming up again - quakes swarmingWed, 20 Mar 2024 00:11:42 +0000
https://www.physicsforums.com/threads/iceland-warming-up-again-quakes-swarming.1056831/
1056831invalid@example.com (davenn)davennIceland warming up again - quakes swarming
]]>59Biographies, history, personal accountsTue, 19 Mar 2024 22:35:02 +0000
https://www.physicsforums.com/threads/biographies-history-personal-accounts.1060020/
1060020invalid@example.com (sbrothy)sbrothyHere's another physics history/philosophy paper. I admit (to my shame)I haven't heard of her and I'm not gonna read it until tomorrow. But yeah....]]>25Fundamental electrokinetics problem calculation using Ohm's LawTue, 19 Mar 2024 22:09:24 +0000
https://www.physicsforums.com/threads/fundamental-electrokinetics-problem-calculation-using-ohms-law.1061039/
1061039invalid@example.com (annin)anninFor a consumer with a resistance of 2 ohms, it has an internal resistance of 0.3 ohms and a voltage of 130 Vwe switch on the power source. The resistance of each connecting thread is 0.15 ohms. What is the voltage drop on the line and what is the terminal voltage?]]>4Fast Food Discussion: Mexican Pizza at Taco BellTue, 19 Mar 2024 21:49:55 +0000
https://www.physicsforums.com/threads/fast-food-discussion-mexican-pizza-at-taco-bell.1015976/
1015976invalid@example.com (kyphysics)kyphysicsThis thread shall be a place where we can talk about anything fast-food related.
Does anyone here actually dislike fast food? I know it's not healthy, but it's sure darn good.
...The Mexican pizza is back at Taco Bell. I like certain items at Taco Bell, but this is not one of them. I...
Read more]]>298"Wave-particle duality" and double-slit experimentTue, 19 Mar 2024 20:33:25 +0000
https://www.physicsforums.com/threads/wave-particle-duality-and-double-slit-experiment.1060884/
1060884invalid@example.com (HighPhy)HighPhySorry to open a new thread.
There are plenty of threads on PF dealing with the issue of "wave-particle duality".
Although not unanimously, many agree that the concept of "wave-particle duality" is outdated. Electrons, photons and all of the underlying entities are neither waves nor particles...
Read more]]>40New member here, please be patient with me 😅Tue, 19 Mar 2024 20:12:38 +0000
https://www.physicsforums.com/threads/new-member-here-please-be-patient-with-me.1061007/
1061007invalid@example.com (physics_student01)physics_student01Hi all,
New PF member. Currently a sophomore Physics student.
I encounter niggling conceptual difficulties in this journey. I was referred to this site by my senior, that the people/mentors here are very kind and would help me navigate this journey provided I am ready to grind & wrestle with...
Read more]]>2Jack JackTue, 19 Mar 2024 20:06:10 +0000
https://www.physicsforums.com/threads/jack-jack.1061024/
1061024invalid@example.com (Jack Jack)Jack JackHi amateur scholar here learning new things
Thanks for having me]]>2Old engineer and physicist...Tue, 19 Mar 2024 20:01:59 +0000
https://www.physicsforums.com/threads/old-engineer-and-physicist.1061029/
1061029invalid@example.com (Sargon38)Sargon38I've been a long-standing member of PF a few decades ago, and now I take up things again after more than 10 years of absence.
I'm into nuclear scientific instrumentation, with a special interest in theoretical physics (but not as theoretical as in my younger years).
I've a degree in electrical...
Read more]]>2Loss of atoms from the surface of the material: How does it work?Tue, 19 Mar 2024 20:01:23 +0000
https://www.physicsforums.com/threads/loss-of-atoms-from-the-surface-of-the-material-how-does-it-work.1060963/
1060963invalid@example.com (PatrickP2)PatrickP2Good morning! A question from a mere layman, so I hope you won't eat me :D
Some time ago I read that every time one solid body makes some contact with another solid body, several billion atoms are lost from the surface of both the first and the second. On the Internet, I once read a post...
Read more]]>14New Member, I look forward to contributing and your kind cooperationTue, 19 Mar 2024 19:52:30 +0000
https://www.physicsforums.com/threads/new-member-i-look-forward-to-contributing-and-your-kind-cooperation.1061031/
1061031invalid@example.com (madladkaiser)madladkaiserHello there, fellow physics enthusiasts, I am a mechanical engineer looking forward to pursuing physics academically.
I am interested in gaining knowledge from this forum and connecting with students and scientists.
Have a nice day, Madladkaiser]]>2Estimating the force exerted by a water jet on a flat plate - Bernoulli vs Momentum EquationTue, 19 Mar 2024 19:46:07 +0000
https://www.physicsforums.com/threads/estimating-the-force-exerted-by-a-water-jet-on-a-flat-plate-bernoulli-vs-momentum-equation.1061036/
1061036invalid@example.com (Pra_S)Pra_SHi,
Case 1:
Imagine a steady liquid water jet with unit cross sectional area - incompressible and inviscid. density D and uniform velocity V. Operating atmospheric pressure is 0.0 Pa.
The jet is in air ( no air resistance ) and hits a stationary flat plate perpendicularly.
Applying momentum...
Read more]]>1Today I LearnedTue, 19 Mar 2024 19:04:18 +0000
https://www.physicsforums.com/threads/today-i-learned.783257/
783257invalid@example.com (Greg Bernhardt)Greg BernhardtEvery day we learn new things. Sometimes it's just a small fact or realization. No matter how trivial or random, let's start recording our daily lessons.
Please start off with "Today I learned". Keep commentary to a minimum and just LIKE posts. I'll start!
Today I learned that you clean...
Read more]]>5813Assume that if the real-valued function h(x) is Lipschitz continuous...Tue, 19 Mar 2024 18:18:14 +0000
https://www.physicsforums.com/threads/assume-that-if-the-real-valued-function-h-x-is-lipschitz-continuous.1060972/
1060972invalid@example.com (docnet)docnetI think the answer is no, since the requirements for Lipschitz continuous and epsilon-delta continuous are different.
The reason I'm asking such an odd question is, I made a mistake by writing a proof of the Lipschitz continuity of ##g(h(x))## using the assumption that ##h(x)## is Lipschitz...
Read more]]>22Can a permeable but non-magnetic rotor be used in an electric motor?Tue, 19 Mar 2024 18:12:27 +0000
https://www.physicsforums.com/threads/can-a-permeable-but-non-magnetic-rotor-be-used-in-an-electric-motor.1060888/
1060888invalid@example.com (ksh93)ksh93Let's say, the disc has a circumference of 1m, made of steel, or copper if you like.
The stator has a north and a south pole facing the surface of the disc, let's say at the perimeter of the disc, one perpendicular to the left and one perpendicular to the right ie opposite sides of the spinning...
Read more]]>11Question about PositronsTue, 19 Mar 2024 17:50:22 +0000
https://www.physicsforums.com/threads/question-about-positrons.1060835/
1060835invalid@example.com (Physicsislove30)Physicsislove30I was researching on the Anderson cloud chamber that discovered the positron in 1932. I couldn't help but wonder, if positron annihilates upon contact with an electron, how was it able to get till the cloud chamber without annihilation? Shouldn't the 2 photons be the only thing observed in the...
Read more]]>5Need some help in complex algebraTue, 19 Mar 2024 17:11:33 +0000
https://www.physicsforums.com/threads/need-some-help-in-complex-algebra.1061033/
1061033invalid@example.com (MatinSAR)MatinSARQuestion 1: Find the modulus and argument of ##z=-\sin \frac {\pi}{8}-i\cos \frac {\pi}{8}##.
The modulus is obviously 1. I can't prove that the argument is ##\frac {-5\pi} {8}##. I think ##\frac {-5\pi} {8}## is not correct ...
What I've done:
$$\tan \theta=\cot \frac {\pi}{8}$$$$\tan...