<?xml version="1.0" encoding="utf-8"?> <rss version="2.0" xmlns:atom="http://www.w3.org/2005/Atom" xmlns:dc="http://purl.org/dc/elements/1.1/" xmlns:content="http://purl.org/rss/1.0/modules/content/" xmlns:slash="http://purl.org/rss/1.0/modules/slash/"> <channel> <title>Physics Forums: Science Discussion, Homework Help, Articles</title> <description>Join Physics Forums, where students, scientists, and enthusiasts come together to explore and discuss the current understanding and practice of various scientific fields.</description> <pubDate>Tue, 18 Feb 2025 00:56:24 +0000</pubDate> <lastBuildDate>Tue, 18 Feb 2025 00:56:24 +0000</lastBuildDate> <generator>Physics Forums: Science Discussion, Homework Help, Articles</generator> <link>https://www.physicsforums.com/</link> <atom:link rel="self" type="application/rss+xml" href="https://www.physicsforums.com/forums/-/index.rss"/> <item> <title>Asteroid 2024 YR4 has a 1% risk of a multi-megaton impact in 2032</title> <pubDate>Tue, 18 Feb 2025 00:35:42 +0000</pubDate> <link>https://www.physicsforums.com/threads/asteroid-2024-yr4-has-a-1-risk-of-a-multi-megaton-impact-in-2032.1078241/</link> <guid isPermaLink="false">1078241</guid> <author>invalid@example.com (mfb)</author> <category domain="https://www.physicsforums.com/forums/astronomy-and-astrophysics.71/"><![CDATA[Astronomy and Astrophysics]]></category> <dc:creator>mfb</dc:creator> <content:encoded><![CDATA[<div class="bbWrapper"><a href="https://en.wikipedia.org/wiki/2024_YR4" target="_blank" class="link link--external" rel="noopener">Asteroid</a>, <a href="https://cneos.jpl.nasa.gov/sentry/details.html#?des=2024%20YR4" target="_blank" class="link link--external" rel="noopener">Data</a> - 1.2% risk of an impact on December 22, 2032. The estimated diameter is 55 m and an impact would likely release an energy of 8 megatons of TNT equivalent, although these numbers have a large uncertainty - it could also be 1 or 100 megatons.<br /> <br /> Currently the object has...<br /> <br /> <a href="https://www.physicsforums.com/threads/asteroid-2024-yr4-has-a-1-risk-of-a-multi-megaton-impact-in-2032.1078241/" class="link link--internal">Read more</a></div>]]></content:encoded> <slash:comments>11</slash:comments> </item> <item> <title>The initial density of an object and its compression into a black hole</title> <pubDate>Tue, 18 Feb 2025 00:30:54 +0000</pubDate> <link>https://www.physicsforums.com/threads/the-initial-density-of-an-object-and-its-compression-into-a-black-hole.1067287/</link> <guid isPermaLink="false">1067287</guid> <author>invalid@example.com (i walk away)</author> <category domain="https://www.physicsforums.com/forums/astronomy-and-astrophysics.71/"><![CDATA[Astronomy and Astrophysics]]></category> <dc:creator>i walk away</dc:creator> <content:encoded><![CDATA[<div class="bbWrapper">The other day, a friend and I had a discussion about black holes, namely how the density of a body affects the process of its transformation into a black hole.<br /> <br /> My friend and I have too little collective knowledge in the field of theoretical physics regarding black holes, so the discussion has...<br /> <br /> <a href="https://www.physicsforums.com/threads/the-initial-density-of-an-object-and-its-compression-into-a-black-hole.1067287/" class="link link--internal">Read more</a></div>]]></content:encoded> <slash:comments>14</slash:comments> </item> <item> <title>Lightning rod how confusing can they be?</title> <pubDate>Tue, 18 Feb 2025 00:30:42 +0000</pubDate> <link>https://www.physicsforums.com/threads/lightning-rod-how-confusing-can-they-be.1078630/</link> <guid isPermaLink="false">1078630</guid> <author>invalid@example.com (Noka22)</author> <category domain="https://www.physicsforums.com/forums/electromagnetism.302/"><![CDATA[Electromagnetism]]></category> <dc:creator>Noka22</dc:creator> <content:encoded><![CDATA[<div class="bbWrapper">Two professors had a discussion one physician and the other eletrical engineer. The first one sad that during a experiment he observed a lightning rod avoiding any discharge, saying that lightning rods when well grounded should avoid discharges and not attract then. The engineer sad that...<br /> <br /> <a href="https://www.physicsforums.com/threads/lightning-rod-how-confusing-can-they-be.1078630/" class="link link--internal">Read more</a></div>]]></content:encoded> <slash:comments>1</slash:comments> </item> <item> <title>Banned member: AlexB23</title> <pubDate>Tue, 18 Feb 2025 00:03:59 +0000</pubDate> <link>https://www.physicsforums.com/threads/banned-member-alexb23.1078628/</link> <guid isPermaLink="false">1078628</guid> <author>invalid@example.com (DaveC426913)</author> <category domain="https://www.physicsforums.com/forums/feedback-and-announcements.19/"><![CDATA[Feedback and Announcements]]></category> <dc:creator>DaveC426913</dc:creator> <content:encoded><![CDATA[<div class="bbWrapper">I notice that @AlexB is banned. <br /> <br /> On first blush, I suspect that this is part of a test; he spoke to me about wanting to be blocked temporarily as an experiment. Did he also speak to the moderators about a similar experiment?</div>]]></content:encoded> <slash:comments>2</slash:comments> </item> <item> <title>What's the best major between Physics &amp; Chemistry for entering MS in Nuclear Engineering?</title> <pubDate>Mon, 17 Feb 2025 23:54:39 +0000</pubDate> <link>https://www.physicsforums.com/threads/whats-the-best-major-between-physics-chemistry-for-entering-ms-in-nuclear-engineering.1078631/</link> <guid isPermaLink="false">1078631</guid> <author>invalid@example.com (Binura Chathumina)</author> <category domain="https://www.physicsforums.com/forums/stem-academic-advising.139/"><![CDATA[STEM Academic Advising]]></category> <dc:creator>Binura Chathumina</dc:creator> <content:encoded><![CDATA[<div class="bbWrapper">I am currently a first-year undergraduate student at the University of Sri Jayewardenepura in Sri Lanka. My majors are Physics, Chemistry, and Polymer Science &amp; Technology. <br /> <br /> In our program, we study these three majors during the first two academic years. After that, we must select one major to...<br /> <br /> <a href="https://www.physicsforums.com/threads/whats-the-best-major-between-physics-chemistry-for-entering-ms-in-nuclear-engineering.1078631/" class="link link--internal">Read more</a></div>]]></content:encoded> <slash:comments>0</slash:comments> </item> <item> <title>Forward-in-time analysis of delayed-choice entanglement swapping</title> <pubDate>Mon, 17 Feb 2025 23:52:48 +0000</pubDate> <link>https://www.physicsforums.com/threads/forward-in-time-analysis-of-delayed-choice-entanglement-swapping.1078114/</link> <guid isPermaLink="false">1078114</guid> <author>invalid@example.com (Sambuco)</author> <category domain="https://www.physicsforums.com/forums/quantum-interpretations-and-foundations.292/"><![CDATA[Quantum Interpretations and Foundations]]></category> <dc:creator>Sambuco</dc:creator> <content:encoded><![CDATA[<div class="bbWrapper">Hi,<br /> <br /> I was following some discussions here about delayed-choice entanglement swapping (DCES) and its implications regarding causality. I&#039;m recently came across the following <a href="https://www.sciencedirect.com/science/article/pii/S0039368124000542" target="_blank" class="link link--external" rel="nofollow ugc noopener">paper</a> where the authors provides a forward-in-time analysis that seems to avoid any backwards influence due to the...<br /> <br /> <a href="https://www.physicsforums.com/threads/forward-in-time-analysis-of-delayed-choice-entanglement-swapping.1078114/" class="link link--internal">Read more</a></div>]]></content:encoded> <slash:comments>202</slash:comments> </item> <item> <title>Recommend architecture/protocol to sync data between MCUs</title> <pubDate>Mon, 17 Feb 2025 23:40:26 +0000</pubDate> <link>https://www.physicsforums.com/threads/recommend-architecture-protocol-to-sync-data-between-mcus.1078243/</link> <guid isPermaLink="false">1078243</guid> <author>invalid@example.com (A.J.710)</author> <category domain="https://www.physicsforums.com/forums/programming-and-computer-science.165/"><![CDATA[Programming and Computer Science]]></category> <dc:creator>A.J.710</dc:creator> <content:encoded><![CDATA[<div class="bbWrapper">This started out as a simple controller only but kept advancing without ability to change the existing architecture and now it&#039;s getting too messy. I&#039;m seeking recommendations on architecture or C libraries or anything to help clean this up because a major change is needed and I&#039;d like to seize...<br /> <br /> <a href="https://www.physicsforums.com/threads/recommend-architecture-protocol-to-sync-data-between-mcus.1078243/" class="link link--internal">Read more</a></div>]]></content:encoded> <slash:comments>12</slash:comments> </item> <item> <title>Random Photos</title> <pubDate>Mon, 17 Feb 2025 23:10:17 +0000</pubDate> <link>https://www.physicsforums.com/threads/random-photos.994801/</link> <guid isPermaLink="false">994801</guid> <author>invalid@example.com (morrobay)</author> <category domain="https://www.physicsforums.com/forums/general-discussion.14/"><![CDATA[General Discussion]]></category> <dc:creator>morrobay</dc:creator> <content:encoded><![CDATA[<div class="bbWrapper">A topic for random photos: Ko-Larn island 7 km West of Pattaya<img src="https://www.physicsforums.com/attachments/img_20200717_114141-jpg.270934/" class="bbImage " style="" alt="IMG_20200717_114141.jpg" title="IMG_20200717_114141.jpg" width="600" height="800" loading="lazy" /></div>]]></content:encoded> <slash:comments>2597</slash:comments> </item> <item> <title>How does detergent lysis work and how to use it?</title> <pubDate>Mon, 17 Feb 2025 22:51:23 +0000</pubDate> <link>https://www.physicsforums.com/threads/how-does-detergent-lysis-work-and-how-to-use-it.1078629/</link> <guid isPermaLink="false">1078629</guid> <author>invalid@example.com (addiven)</author> <category domain="https://www.physicsforums.com/forums/chemistry.83/"><![CDATA[Chemistry]]></category> <dc:creator>addiven</dc:creator> <content:encoded><![CDATA[<div class="bbWrapper">I have a project for school, I want to analyse and compare the protein contents of some different species of fish. The problem I&#039;m stuck with, is just separating the protein from nucleic acids and other organic matter. I want to get the concentration by either using the Biuret test, or using...<br /> <br /> <a href="https://www.physicsforums.com/threads/how-does-detergent-lysis-work-and-how-to-use-it.1078629/" class="link link--internal">Read more</a></div>]]></content:encoded> <slash:comments>0</slash:comments> </item> <item> <title>Confused regarding Electricity Basics; Helping Kid with Project</title> <pubDate>Mon, 17 Feb 2025 22:49:39 +0000</pubDate> <link>https://www.physicsforums.com/threads/confused-regarding-electricity-basics-helping-kid-with-project.1078576/</link> <guid isPermaLink="false">1078576</guid> <author>invalid@example.com (Bluesy)</author> <category domain="https://www.physicsforums.com/forums/electromagnetism.302/"><![CDATA[Electromagnetism]]></category> <dc:creator>Bluesy</dc:creator> <content:encoded><![CDATA[<div class="bbWrapper">Hello,<br /> <br /> My 10 year old is doing a science project in which he places a zinc nail and copper nail in a liquid, hooks each nail up to a voltmeter and then measures the recorded voltage for each substance.<br /> <br /> Liquids include lemon juice, distilled water and ammonia. <br /> <br /> The book from which he got the...<br /> <br /> <a href="https://www.physicsforums.com/threads/confused-regarding-electricity-basics-helping-kid-with-project.1078576/" class="link link--internal">Read more</a></div>]]></content:encoded> <slash:comments>10</slash:comments> </item> <item> <title>Official Response to "Allegations of AI misuse in PF"</title> <pubDate>Mon, 17 Feb 2025 22:38:23 +0000</pubDate> <link>https://www.physicsforums.com/threads/official-response-to-allegations-of-ai-misuse-in-pf.1078532/</link> <guid isPermaLink="false">1078532</guid> <author>invalid@example.com (Greg Bernhardt)</author> <category domain="https://www.physicsforums.com/forums/feedback-and-announcements.19/"><![CDATA[Feedback and Announcements]]></category> <dc:creator>Greg Bernhardt</dc:creator> <content:encoded><![CDATA[<div class="bbWrapper">Dear Physics Forums members,<br /> <br /> I want to address a serious mistake that has impacted our community’s trust. A deeply regretful error of judgment that I alone am responsible and accountable for. No other staff had any knowledge.<br /> <br /> During the past several months, to counter declining engagement, I...<br /> <br /> <a href="https://www.physicsforums.com/threads/official-response-to-allegations-of-ai-misuse-in-pf.1078532/" class="link link--internal">Read more</a></div>]]></content:encoded> <slash:comments>20</slash:comments> </item> <item> <title>How to calculate how much energy a pneumatic system would need?</title> <pubDate>Mon, 17 Feb 2025 22:10:22 +0000</pubDate> <link>https://www.physicsforums.com/threads/how-to-calculate-how-much-energy-a-pneumatic-system-would-need.1078603/</link> <guid isPermaLink="false">1078603</guid> <author>invalid@example.com (fulano)</author> <category domain="https://www.physicsforums.com/forums/mechanical-engineering.101/"><![CDATA[Mechanical Engineering]]></category> <dc:creator>fulano</dc:creator> <content:encoded><![CDATA[<div class="bbWrapper">Well, I was trying to predict how much energy a pneumatic system would need in order to actuate in a specific force and speed, but it seems that I would need too little energy for too much work.<br /> <br /> So, I was wondering how I would go on about making a pneumatic system with artificial muscles, they...<br /> <br /> <a href="https://www.physicsforums.com/threads/how-to-calculate-how-much-energy-a-pneumatic-system-would-need.1078603/" class="link link--internal">Read more</a></div>]]></content:encoded> <slash:comments>23</slash:comments> </item> <item> <title>Uniform convergence of family of functions with continuous index</title> <pubDate>Mon, 17 Feb 2025 22:08:33 +0000</pubDate> <link>https://www.physicsforums.com/threads/uniform-convergence-of-family-of-functions-with-continuous-index.1078627/</link> <guid isPermaLink="false">1078627</guid> <author>invalid@example.com (psie)</author> <category domain="https://www.physicsforums.com/forums/calculus.109/"><![CDATA[Calculus]]></category> <dc:creator>psie</dc:creator> <content:encoded><![CDATA[<div class="bbWrapper">In Rudin&#039;s PMA, when he proves the Stirling formula, he defines a continuous, decreasing function ##h:(-1,\infty)\to\mathbb R## such that ##h(u)\to\infty## as ##u\to -1## and ##h(u)\to 0## as ##u\to\infty##. Then he derives an integral expression for ##\Gamma(x+1)##, where ##\Gamma## is the...<br /> <br /> <a href="https://www.physicsforums.com/threads/uniform-convergence-of-family-of-functions-with-continuous-index.1078627/" class="link link--internal">Read more</a></div>]]></content:encoded> <slash:comments>2</slash:comments> </item> <item> <title>ChatGPT Examples, Good and Bad</title> <pubDate>Mon, 17 Feb 2025 21:25:02 +0000</pubDate> <link>https://www.physicsforums.com/threads/chatgpt-examples-good-and-bad.1048757/</link> <guid isPermaLink="false">1048757</guid> <author>invalid@example.com (anorlunda)</author> <category domain="https://www.physicsforums.com/forums/computing-and-technology.188/"><![CDATA[Computing and Technology]]></category> <dc:creator>anorlunda</dc:creator> <content:encoded><![CDATA[<div class="bbWrapper">I&#039;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.<br /> <br /> (I had problems with copy/paste of...<br /> <br /> <a href="https://www.physicsforums.com/threads/chatgpt-examples-good-and-bad.1048757/" class="link link--internal">Read more</a></div>]]></content:encoded> <slash:comments>145</slash:comments> </item> <item> <title>Does &lt;Code&gt; feature not work?</title> <pubDate>Mon, 17 Feb 2025 21:00:17 +0000</pubDate> <link>https://www.physicsforums.com/threads/does-code-feature-not-work.1078456/</link> <guid isPermaLink="false">1078456</guid> <author>invalid@example.com (DaveC426913)</author> <category domain="https://www.physicsforums.com/forums/feedback-and-announcements.19/"><![CDATA[Feedback and Announcements]]></category> <dc:creator>DaveC426913</dc:creator> <content:encoded><![CDATA[<div class="bbWrapper">I cannot post code with the CODE tags.<br /> Here is a screen grab of the code I tried to post, and the error it thorws when I try to save it.<br /> <img src="https://www.physicsforums.com/attachments/1738984058549-png.356996/" class="bbImage " style="" alt="1738984058549.png" title="1738984058549.png" width="800" height="517" loading="lazy" /><br /> <br /> <img src="https://www.physicsforums.com/attachments/1738983772916-png.356994/" class="bbImage " style="" alt="1738983772916.png" title="1738983772916.png" width="800" height="140" loading="lazy" /><br /> <br /> <br /> I am going to start small and see where it breaks.<br /> <br /> It chokes on any <b>script</b> line.<br /> <br /> <div class="bbCodeBlock bbCodeBlock--screenLimited bbCodeBlock--code language-html " data-xf-init="CMTV-code-block"> <div class="bbCodeBlock-header"> <div class="bbCodeBlock-title"> <span title="HTML"> Title: </span> </div> <div class="bbCodeBlock-actions"> <i class="fa--xf fal fa-expand-alt action action--expand action--hidden" aria-hidden="true" title="Expand" data-xf-init="tooltip" data-xf-click="CMTV-code-block-expand"></i> <i class="fa--xf fal fa-compress-alt action action--collapse action--hidden" aria-hidden="true" title="Collapse" data-xf-init="tooltip" data-xf-click="CMTV-code-block-collapse"></i> <i class="fa--xf fal fa-paste action action--copy" aria-hidden="true" title="Copy" data-xf-init="tooltip"></i> </div> </div> <div class="bbCodeBlock-content" dir="ltr"> <pre class="bbCodeCode line-numbers" dir="ltr" data-line="" data-xf-init="CMTV-code-block-extend" data-lang="html"><code>&lt;!DOCTYPE html&gt; &lt;html lang=&quot;en&quot;&gt;...</code></pre> </div> <div class="bbCodeBlock-grip resizer--hidden" data-xf-init="CMTV-code-block-resizer"> <i class="fa--xf fal fa-grip-horizontal" aria-hidden="true"></i> </div> </div><br /> <a href="https://www.physicsforums.com/threads/does-code-feature-not-work.1078456/" class="link link--internal">Read more</a></div>]]></content:encoded> <slash:comments>22</slash:comments> </item> <item> <title>I Need Help on Understanding Some Basic Astrophysics / Sand Clock Universe</title> <pubDate>Mon, 17 Feb 2025 20:57:09 +0000</pubDate> <link>https://www.physicsforums.com/threads/i-need-help-on-understanding-some-basic-astrophysics-sand-clock-universe.1078452/</link> <guid isPermaLink="false">1078452</guid> <author>invalid@example.com (CanerKaraca)</author> <category domain="https://www.physicsforums.com/forums/astronomy-and-astrophysics.71/"><![CDATA[Astronomy and Astrophysics]]></category> <dc:creator>CanerKaraca</dc:creator> <content:encoded><![CDATA[<div class="bbWrapper">I need help on an idea I have had for the last couple of months. I am not an astrophysicist so I am here to get some direction on whether this makes sense or not.<br /> <br /> It is well known that the fabric of space can ben bent by the objects in it. Planets and astreoids can only bend the space-time so...<br /> <br /> <a href="https://www.physicsforums.com/threads/i-need-help-on-understanding-some-basic-astrophysics-sand-clock-universe.1078452/" class="link link--internal">Read more</a></div>]]></content:encoded> <slash:comments>5</slash:comments> </item> <item> <title>MCNP Data Card Errors</title> <pubDate>Mon, 17 Feb 2025 20:52:25 +0000</pubDate> <link>https://www.physicsforums.com/threads/mcnp-data-card-errors.1078607/</link> <guid isPermaLink="false">1078607</guid> <author>invalid@example.com (MadGander)</author> <category domain="https://www.physicsforums.com/forums/nuclear-engineering.106/"><![CDATA[Nuclear Engineering]]></category> <dc:creator>MadGander</dc:creator> <content:encoded><![CDATA[<div class="bbWrapper">I&#039;m trying to resolve two separate fatal errors in my MCNP deck. One is claiming that I&#039;m mixing atom and weight fractions within a single material card, which I&#039;m clearly not if you take a peek at the material definitions. The other is saying that I have an odd number of entries, indicating...<br /> <br /> <a href="https://www.physicsforums.com/threads/mcnp-data-card-errors.1078607/" class="link link--internal">Read more</a></div>]]></content:encoded> <slash:comments>1</slash:comments> </item> <item> <title>A new realistic stochastic interpretation of Quantum Mechanics</title> <pubDate>Mon, 17 Feb 2025 20:47:36 +0000</pubDate> <link>https://www.physicsforums.com/threads/a-new-realistic-stochastic-interpretation-of-quantum-mechanics.1060576/</link> <guid isPermaLink="false">1060576</guid> <author>invalid@example.com (PAllen)</author> <category domain="https://www.physicsforums.com/forums/quantum-interpretations-and-foundations.292/"><![CDATA[Quantum Interpretations and Foundations]]></category> <dc:creator>PAllen</dc:creator> <content:encoded><![CDATA[<div class="bbWrapper">These papers claim to present a realistic stochastic interpretation of quantum mechanics that obeys a stochastic form of local causality. (A lecture I recently attended mentioned these papers). It also claims the Born rule as a natural consequence rather than an assumption. This appears to me to...<br /> <br /> <a href="https://www.physicsforums.com/threads/a-new-realistic-stochastic-interpretation-of-quantum-mechanics.1060576/" class="link link--internal">Read more</a></div>]]></content:encoded> <slash:comments>519</slash:comments> </item> <item> <title>Another rotation problem</title> <pubDate>Mon, 17 Feb 2025 20:27:32 +0000</pubDate> <link>https://www.physicsforums.com/threads/another-rotation-problem.1078622/</link> <guid isPermaLink="false">1078622</guid> <author>invalid@example.com (palaphys)</author> <category domain="https://www.physicsforums.com/forums/introductory-physics-homework-help.153/"><![CDATA[Introductory Physics Homework Help]]></category> <dc:creator>palaphys</dc:creator> <content:encoded><![CDATA[<div class="bbWrapper">[Mentors&#039; note - this question was spun off from <a href="https://www.physicsforums.com/threads/rotating-ring-on-a-rough-surface-but-with-a-twist.1078618/#post-7243282" class="link link--internal">https://www.physicsforums.com/threa...urface-but-with-a-twist.1078618/#post-7243282</a> which contains the homework template information]<br /> <br /> I&#039;m not sure if I can add on by adding a similar question, if I am not allowed...<br /> <br /> <a href="https://www.physicsforums.com/threads/another-rotation-problem.1078622/" class="link link--internal">Read more</a></div>]]></content:encoded> <slash:comments>1</slash:comments> </item> <item> <title>Collection of Lame Jokes</title> <pubDate>Mon, 17 Feb 2025 20:07:07 +0000</pubDate> <link>https://www.physicsforums.com/threads/collection-of-lame-jokes.25301/</link> <guid isPermaLink="false">25301</guid> <author>invalid@example.com (quddusaliquddus)</author> <category domain="https://www.physicsforums.com/forums/general-discussion.14/"><![CDATA[General Discussion]]></category> <dc:creator>quddusaliquddus</dc:creator> <content:encoded><![CDATA[<div class="bbWrapper">Lamest joke you know ... :zzz:</div>]]></content:encoded> <slash:comments>21034</slash:comments> </item> <item> <title>Looking for upper division modern physics book</title> <pubDate>Mon, 17 Feb 2025 19:38:47 +0000</pubDate> <link>https://www.physicsforums.com/threads/looking-for-upper-division-modern-physics-book.1078547/</link> <guid isPermaLink="false">1078547</guid> <author>invalid@example.com (dainceptionman_02)</author> <category domain="https://www.physicsforums.com/forums/science-and-math-textbooks.21/"><![CDATA[Science and Math Textbooks]]></category> <dc:creator>dainceptionman_02</dc:creator> <content:encoded><![CDATA[<div class="bbWrapper">i recently bought books for (self study) Mathematical Methods of Physics, Thermal Physics, Classical Mechanics, and Introduction to Electrodynamics. I should probably get an upper division Modern Physics book before going to Quantum Mechanics (Griffiths). What is a good/usual Modern Physics...<br /> <br /> <a href="https://www.physicsforums.com/threads/looking-for-upper-division-modern-physics-book.1078547/" class="link link--internal">Read more</a></div>]]></content:encoded> <slash:comments>8</slash:comments> </item> <item> <title>Would discovery of a galaxy without dark matter disprove MOND?</title> <pubDate>Mon, 17 Feb 2025 19:17:21 +0000</pubDate> <link>https://www.physicsforums.com/threads/would-discovery-of-a-galaxy-without-dark-matter-disprove-mond.1058814/</link> <guid isPermaLink="false">1058814</guid> <author>invalid@example.com (lamdar)</author> <category domain="https://www.physicsforums.com/forums/astronomy-and-astrophysics.71/"><![CDATA[Astronomy and Astrophysics]]></category> <dc:creator>lamdar</dc:creator> <content:encoded><![CDATA[<div class="bbWrapper">I’ve been reading about LCDM and MOND recently. And there have been reports of galaxies with little dark matter. I know the lack of dark matter in NGC1052-DF2 was shown not true afterwards. But if such a galaxy without dark matter is actually discovered, would this be sufficient to disprove MOND?</div>]]></content:encoded> <slash:comments>13</slash:comments> </item> <item> <title>Cosmic ray origins</title> <pubDate>Mon, 17 Feb 2025 19:01:46 +0000</pubDate> <link>https://www.physicsforums.com/threads/cosmic-ray-origins.1078617/</link> <guid isPermaLink="false">1078617</guid> <author>invalid@example.com (snorkack)</author> <category domain="https://www.physicsforums.com/forums/astronomy-and-astrophysics.71/"><![CDATA[Astronomy and Astrophysics]]></category> <dc:creator>snorkack</dc:creator> <content:encoded><![CDATA[<div class="bbWrapper">Is there any consensus as to how much of the primary cosmic rays come from supernovae, and of which type, how much from quasars, how much from kilonovae?<br /> How does the mass number distribution of primary cosmic rays compare against average of stars? Against Type I and II supernovae, and...<br /> <br /> <a href="https://www.physicsforums.com/threads/cosmic-ray-origins.1078617/" class="link link--internal">Read more</a></div>]]></content:encoded> <slash:comments>1</slash:comments> </item> <item> <title>Wordle Lovers - Play the NYT Daily Game</title> <pubDate>Mon, 17 Feb 2025 18:50:02 +0000</pubDate> <link>https://www.physicsforums.com/threads/wordle-lovers-play-the-nyt-daily-game.1016903/</link> <guid isPermaLink="false">1016903</guid> <author>invalid@example.com (fresh_42)</author> <category domain="https://www.physicsforums.com/forums/general-discussion.14/"><![CDATA[General Discussion]]></category> <dc:creator>fresh_42</dc:creator> <content:encoded><![CDATA[<div class="bbWrapper">This thread is for all who like the daily Wordle game of the New York Times as much as I do.<br /> <br /> The rules:<br /> <br /> 1) <a href="https://www.nytimes.com/games/wordle/index.html" target="_blank" class="link link--external" rel="noopener">https://www.nytimes.com/games/wordle/index.html</a><br /> 2) Post your result.<br /> 3) Do not spoil the answer.</div>]]></content:encoded> <slash:comments>6442</slash:comments> </item> <item> <title>Question about an 8th grade math problem</title> <pubDate>Mon, 17 Feb 2025 18:42:45 +0000</pubDate> <link>https://www.physicsforums.com/threads/question-about-an-8th-grade-math-problem.1078608/</link> <guid isPermaLink="false">1078608</guid> <author>invalid@example.com (murshid_islam)</author> <category domain="https://www.physicsforums.com/forums/precalculus-mathematics-homework-help.155/"><![CDATA[Precalculus Mathematics Homework Help]]></category> <dc:creator>murshid_islam</dc:creator> <content:encoded><![CDATA[<div class="bbWrapper"><b>TL;DR Summary:</b> It seems like not enough information is given for this 8th grade math problem<br /> <br /> <img src="https://www.physicsforums.com/attachments/cubepyramid-png.357404/" class="bbImage " style="" alt="cubepyramid.png" title="cubepyramid.png" width="800" height="215" loading="lazy" /><br /> <br /> For the attached problem,<br /> let b = the side length of the square base of the pyramid and<br /> h = the height of the pyramid<br /> 1/3 b²h = 9<br /> b²h = 27<br /> <br /> One simple and obvious...<br /> <br /> <a href="https://www.physicsforums.com/threads/question-about-an-8th-grade-math-problem.1078608/" class="link link--internal">Read more</a></div>]]></content:encoded> <slash:comments>10</slash:comments> </item> <item> <title>Improving coupling of a resonator by looking at surface currents</title> <pubDate>Mon, 17 Feb 2025 18:02:10 +0000</pubDate> <link>https://www.physicsforums.com/threads/improving-coupling-of-a-resonator-by-looking-at-surface-currents.1078626/</link> <guid isPermaLink="false">1078626</guid> <author>invalid@example.com (yefj)</author> <category domain="https://www.physicsforums.com/forums/electrical-engineering.102/"><![CDATA[Electrical Engineering]]></category> <dc:creator>yefj</dc:creator> <content:encoded><![CDATA[<div class="bbWrapper">Hello , In the system below there is a mode i am trying to couple.<br /> at weak coupling I get a certain surface current responce and in stronger coupling I have different responce as shown below.<br /> How can I see from the surface currents where can i improve the coupling in my model...<br /> <br /> <a href="https://www.physicsforums.com/threads/improving-coupling-of-a-resonator-by-looking-at-surface-currents.1078626/" class="link link--internal">Read more</a></div>]]></content:encoded> <slash:comments>0</slash:comments> </item> <item> <title>A new form of addition?</title> <pubDate>Mon, 17 Feb 2025 17:54:44 +0000</pubDate> <link>https://www.physicsforums.com/threads/a-new-form-of-addition.1078624/</link> <guid isPermaLink="false">1078624</guid> <author>invalid@example.com (biljanica)</author> <category domain="https://www.physicsforums.com/forums/general-math.73/"><![CDATA[General Math]]></category> <dc:creator>biljanica</dc:creator> <content:encoded><![CDATA[<div class="bbWrapper">Can mathematics rest on new foundations? See the attachment.<br /> <br /> a little explanation about the form of addition<br /> <br /> adding or joining , as performed<br /> <br /> R a+b=c same as now, combined numbers 2<u>2</u>2+3<u>3</u>=2<u>2</u>5<u>3</u>, when they are the same along (gap) they are joined, here 2 and 3, we get 5...<br /> <br /> <a href="https://www.physicsforums.com/threads/a-new-form-of-addition.1078624/" class="link link--internal">Read more</a></div>]]></content:encoded> <slash:comments>8</slash:comments> </item> <item> <title>Rotating ring on a rough surface- but with a twist</title> <pubDate>Mon, 17 Feb 2025 17:41:23 +0000</pubDate> <link>https://www.physicsforums.com/threads/rotating-ring-on-a-rough-surface-but-with-a-twist.1078618/</link> <guid isPermaLink="false">1078618</guid> <author>invalid@example.com (palaphys)</author> <category domain="https://www.physicsforums.com/forums/introductory-physics-homework-help.153/"><![CDATA[Introductory Physics Homework Help]]></category> <dc:creator>palaphys</dc:creator> <content:encoded><![CDATA[<div class="bbWrapper">Honestly, I was very confused looking at the problem. With intuition, it is clear that the ring will roll towards the right. But what direction would friction be acting in? That was my first thought.<br /> However I am unable to figure this out, leaving me stuck here.<br /> <br /> My only attempt here was to find...<br /> <br /> <a href="https://www.physicsforums.com/threads/rotating-ring-on-a-rough-surface-but-with-a-twist.1078618/" class="link link--internal">Read more</a></div>]]></content:encoded> <slash:comments>54</slash:comments> </item> <item> <title>Mnemonic for Lewis acids and bases</title> <pubDate>Mon, 17 Feb 2025 17:40:30 +0000</pubDate> <link>https://www.physicsforums.com/threads/mnemonic-for-lewis-acids-and-bases.1078594/</link> <guid isPermaLink="false">1078594</guid> <author>invalid@example.com (em3ry)</author> <category domain="https://www.physicsforums.com/forums/chemistry.83/"><![CDATA[Chemistry]]></category> <dc:creator>em3ry</dc:creator> <content:encoded><![CDATA[<div class="bbWrapper">Blob-like Bases are the basis of Lewis acid-base chemistry.<br /> The basis is that bases act like the blob. Their lone pair orbital envelops and swallows bare protons.<br /> <br /> Basis-Bases-Blob<br /> <br /> Lone pairs ARE the only true bases. They accept protons and other similar species. Water has protons and lone...<br /> <br /> <a href="https://www.physicsforums.com/threads/mnemonic-for-lewis-acids-and-bases.1078594/" class="link link--internal">Read more</a></div>]]></content:encoded> <slash:comments>11</slash:comments> </item> <item> <title>Share Animal Pictures: For Animal Lovers</title> <pubDate>Mon, 17 Feb 2025 17:00:56 +0000</pubDate> <link>https://www.physicsforums.com/threads/share-animal-pictures-for-animal-lovers.583729/</link> <guid isPermaLink="false">583729</guid> <author>invalid@example.com (micromass)</author> <category domain="https://www.physicsforums.com/forums/general-discussion.14/"><![CDATA[General Discussion]]></category> <dc:creator>micromass</dc:creator> <content:encoded><![CDATA[<div class="bbWrapper">Post your favorite animal pictures here!</div>]]></content:encoded> <slash:comments>2908</slash:comments> </item> <item> <title>Why is it necessary to start this experiment with the water level at 400mL?</title> <pubDate>Mon, 17 Feb 2025 16:31:54 +0000</pubDate> <link>https://www.physicsforums.com/threads/why-is-it-necessary-to-start-this-experiment-with-the-water-level-at-400ml.1078511/</link> <guid isPermaLink="false">1078511</guid> <author>invalid@example.com (Aurelius120)</author> <category domain="https://www.physicsforums.com/forums/introductory-physics-homework-help.153/"><![CDATA[Introductory Physics Homework Help]]></category> <dc:creator>Aurelius120</dc:creator> <content:encoded><![CDATA[<div class="bbWrapper"><img src="https://www.physicsforums.com/attachments/1000033589-jpg.357147/" class="bbImage " style="" alt="1000033589.jpg" title="1000033589.jpg" width="400" height="229" loading="lazy" /><br /> This is a water spirometer. You have to exhale as hard as possible the pulley rotates and the pointer shows the volume exhaled.<br /> <br /> The procedure wants us to keep the pointer at 400 and later subtract 400 to get the correct volume. <br /> <br /> <b><span style="font-family: 'times new roman'">Why can&#039;t we start at zero?</span></b><br /> <br /> Teacher...<br /> <br /> <a href="https://www.physicsforums.com/threads/why-is-it-necessary-to-start-this-experiment-with-the-water-level-at-400ml.1078511/" class="link link--internal">Read more</a></div>]]></content:encoded> <slash:comments>35</slash:comments> </item> <item> <title>Calculation of probabilities assuming correlation between events</title> <pubDate>Mon, 17 Feb 2025 16:22:50 +0000</pubDate> <link>https://www.physicsforums.com/threads/calculation-of-probabilities-assuming-correlation-between-events.1078625/</link> <guid isPermaLink="false">1078625</guid> <author>invalid@example.com (Bob Anger)</author> <category domain="https://www.physicsforums.com/forums/set-theory-logic-probability-statistics.78/"><![CDATA[Set Theory, Logic, Probability, Statistics]]></category> <dc:creator>Bob Anger</dc:creator> <content:encoded><![CDATA[<div class="bbWrapper">Hi all, <br /> I need your help regarding a probability problem for which I couldn’t find an answer. The topic has been presented by a finance Professor at MIT in a paper published a few years ago. <br /> <br /> Here is the problem: A medical experiment, seeking the development of a new medical drug, has a...<br /> <br /> <a href="https://www.physicsforums.com/threads/calculation-of-probabilities-assuming-correlation-between-events.1078625/" class="link link--internal">Read more</a></div>]]></content:encoded> <slash:comments>0</slash:comments> </item> <item> <title>The satellite and its work done</title> <pubDate>Mon, 17 Feb 2025 15:59:47 +0000</pubDate> <link>https://www.physicsforums.com/threads/the-satellite-and-its-work-done.1078620/</link> <guid isPermaLink="false">1078620</guid> <author>invalid@example.com (HLAung)</author> <category domain="https://www.physicsforums.com/forums/general-discussion.14/"><![CDATA[General Discussion]]></category> <dc:creator>HLAung</dc:creator> <content:encoded><![CDATA[<div class="bbWrapper">If the starting and ending points are the same, there is no displacement.<br /> If there is no displacement, no matter how much energy is exerted, work is not done.<br /> <br /> So, is an artificial satellite orbiting the Earth with the same starting and ending points not working?<br /> <br /> In my opinion, in such a...<br /> <br /> <a href="https://www.physicsforums.com/threads/the-satellite-and-its-work-done.1078620/" class="link link--internal">Read more</a></div>]]></content:encoded> <slash:comments>2</slash:comments> </item> <item> <title>The work done by an artificial satellite</title> <pubDate>Mon, 17 Feb 2025 15:47:48 +0000</pubDate> <link>https://www.physicsforums.com/threads/the-work-done-by-an-artificial-satellite.1078561/</link> <guid isPermaLink="false">1078561</guid> <author>invalid@example.com (HLAung)</author> <category domain="https://www.physicsforums.com/forums/general-discussion.14/"><![CDATA[General Discussion]]></category> <dc:creator>HLAung</dc:creator> <content:encoded><![CDATA[<div class="bbWrapper">The work done by an artificial satellite in an orbit in a day is equal to the total energy produced, utilized and stored by the satellite during that day.</div>]]></content:encoded> <slash:comments>4</slash:comments> </item> <item> <title>Antenna made from a pair of metal cones, radiation gain verses frequency.</title> <pubDate>Mon, 17 Feb 2025 15:42:14 +0000</pubDate> <link>https://www.physicsforums.com/threads/antenna-made-from-a-pair-of-metal-cones-radiation-gain-verses-frequency.1078623/</link> <guid isPermaLink="false">1078623</guid> <author>invalid@example.com (Spinnor)</author> <category domain="https://www.physicsforums.com/forums/electromagnetism.302/"><![CDATA[Electromagnetism]]></category> <dc:creator>Spinnor</dc:creator> <content:encoded><![CDATA[<div class="bbWrapper">Take one of a pair of metal cones and put a coax cable sized hole in the center of that cone. Let the &quot;tops&quot; of the cones face each other separated a distance a fraction of the diameter of the metal cones. Take a coax cable and connect it to the hole of the one cone (from the &quot;inside&quot; of the...<br /> <br /> <a href="https://www.physicsforums.com/threads/antenna-made-from-a-pair-of-metal-cones-radiation-gain-verses-frequency.1078623/" class="link link--internal">Read more</a></div>]]></content:encoded> <slash:comments>1</slash:comments> </item> <item> <title>How can a quantum computer be faster than a classic computer?</title> <pubDate>Mon, 17 Feb 2025 14:55:21 +0000</pubDate> <link>https://www.physicsforums.com/threads/how-can-a-quantum-computer-be-faster-than-a-classic-computer.1078605/</link> <guid isPermaLink="false">1078605</guid> <author>invalid@example.com (KingGambit)</author> <category domain="https://www.physicsforums.com/forums/computing-and-technology.188/"><![CDATA[Computing and Technology]]></category> <dc:creator>KingGambit</dc:creator> <content:encoded><![CDATA[<div class="bbWrapper">Dear PF Forum,<br /> <br /> It&#039;s been a while since I logged in. And I hope everybody is in good health.<br /> Here I have a question concerning quantum computer.<br /> First, I&#039;m no unfamiliar with a computer. I&#039;m a computer programmer, but I don&#039;t know any physics.<br /> How can a quantum computer be a lot faster then an...<br /> <br /> <a href="https://www.physicsforums.com/threads/how-can-a-quantum-computer-be-faster-than-a-classic-computer.1078605/" class="link link--internal">Read more</a></div>]]></content:encoded> <slash:comments>23</slash:comments> </item> <item> <title>Zero acceleration = zero net force?</title> <pubDate>Mon, 17 Feb 2025 14:43:43 +0000</pubDate> <link>https://www.physicsforums.com/threads/zero-acceleration-zero-net-force.1078578/</link> <guid isPermaLink="false">1078578</guid> <author>invalid@example.com (paulb203)</author> <category domain="https://www.physicsforums.com/forums/mechanics.299/"><![CDATA[Mechanics]]></category> <dc:creator>paulb203</dc:creator> <content:encoded><![CDATA[<div class="bbWrapper">From Khan Academy;<br /> <br /> “As truck moves with constant velocity down the road, its acceleration is zero.<br /> Therefore, the net force acting on the box must be<br /> zero.”<br /> <br /> Which forces are involved in a truck moving with constant velocity (and therefore no acceleration)?<br /> <br /> The gravitational force and the...<br /> <br /> <a href="https://www.physicsforums.com/threads/zero-acceleration-zero-net-force.1078578/" class="link link--internal">Read more</a></div>]]></content:encoded> <slash:comments>18</slash:comments> </item> <item> <title>Quasi-Elastic Scattering Peak-Shift</title> <pubDate>Mon, 17 Feb 2025 13:56:07 +0000</pubDate> <link>https://www.physicsforums.com/threads/quasi-elastic-scattering-peak-shift.1078621/</link> <guid isPermaLink="false">1078621</guid> <author>invalid@example.com (deuteron)</author> <category domain="https://www.physicsforums.com/forums/high-energy-nuclear-particle-physics.65/"><![CDATA[High Energy, Nuclear, Particle Physics]]></category> <dc:creator>deuteron</dc:creator> <content:encoded><![CDATA[<div class="bbWrapper">We were told in my particle physics lectures that in a quasi-elastic scattering, in a diagram of scattered electron energy ##E&#039;##-counts corresponding to an electron-nucleus scattering experiment at a fixed detector angle ##\theta##, we would have a peak corresponding to the electrons that have...<br /> <br /> <a href="https://www.physicsforums.com/threads/quasi-elastic-scattering-peak-shift.1078621/" class="link link--internal">Read more</a></div>]]></content:encoded> <slash:comments>0</slash:comments> </item> <item> <title>Simplifying terms of Ricci tensor</title> <pubDate>Mon, 17 Feb 2025 13:39:35 +0000</pubDate> <link>https://www.physicsforums.com/threads/simplifying-terms-of-ricci-tensor.1078619/</link> <guid isPermaLink="false">1078619</guid> <author>invalid@example.com (Safinaz)</author> <category domain="https://www.physicsforums.com/forums/advanced-physics-homework-help.154/"><![CDATA[Advanced Physics Homework Help]]></category> <dc:creator>Safinaz</dc:creator> <content:encoded><![CDATA[<div class="bbWrapper">So that they become:<br /> <br /> ##<br /> g^{\sigma \rho} \nabla_\sigma \nabla_\rho R ~g_{\mu\nu} + R ~R_{\mu\nu} - \nabla_\mu \nabla_\nu R<br /> ##</div>]]></content:encoded> <slash:comments>0</slash:comments> </item> <item> <title>Random Thoughts 7</title> <pubDate>Mon, 17 Feb 2025 13:08:39 +0000</pubDate> <link>https://www.physicsforums.com/threads/random-thoughts-7.1056780/</link> <guid isPermaLink="false">1056780</guid> <author>invalid@example.com (Evo)</author> <category domain="https://www.physicsforums.com/forums/general-discussion.14/"><![CDATA[General Discussion]]></category> <dc:creator>Evo</dc:creator> <content:encoded><![CDATA[<div class="bbWrapper">Time to start a new thread.<br /> <br /> Here is the last page of part 6.<br /> <br /> <a href="https://www.physicsforums.com/threads/random-thoughts-part-6.875108/page-317#post-6960672" class="link link--internal">https://www.physicsforums.com/threads/random-thoughts-part-6.875108/page-317#post-6960672</a></div>]]></content:encoded> <slash:comments>1368</slash:comments> </item> <item> <title>[solved] tag in front of thread title?</title> <pubDate>Mon, 17 Feb 2025 12:39:22 +0000</pubDate> <link>https://www.physicsforums.com/threads/solved-tag-in-front-of-thread-title.1078606/</link> <guid isPermaLink="false">1078606</guid> <author>invalid@example.com (erobz)</author> <category domain="https://www.physicsforums.com/forums/feedback-and-announcements.19/"><![CDATA[Feedback and Announcements]]></category> <dc:creator>erobz</dc:creator> <content:encoded><![CDATA[<div class="bbWrapper">What does the [solved] tag do here when its put in front of a title. Does it mean an adequate solution was obtained for a thread as far as an advisor is concerned, is it a dog whistle to not participate further?</div>]]></content:encoded> <slash:comments>5</slash:comments> </item> <item> <title>(Seemingly) Random Sequences</title> <pubDate>Mon, 17 Feb 2025 12:04:16 +0000</pubDate> <link>https://www.physicsforums.com/threads/seemingly-random-sequences.1078614/</link> <guid isPermaLink="false">1078614</guid> <author>invalid@example.com (Monoxdifly)</author> <category domain="https://www.physicsforums.com/forums/general-math.73/"><![CDATA[General Math]]></category> <dc:creator>Monoxdifly</dc:creator> <content:encoded><![CDATA[<div class="bbWrapper">Given a sequence 32, 16, 4, 18, 9, 3, .... The next numbers are ....<br /> A. 17, 8, 5<br /> B. 17, 6<br /> C. 17, 4<br /> D. 16, 4<br /> E. 14, 8<br /> <br /> My train of thought was to group the sequence into three numbers, so we get (32, 16, 4) and (18, 9, 3).<br /> 32 is two times of 16 which is square of 4.<br /> 18 is two times of 9 which is...<br /> <br /> <a href="https://www.physicsforums.com/threads/seemingly-random-sequences.1078614/" class="link link--internal">Read more</a></div>]]></content:encoded> <slash:comments>1</slash:comments> </item> <item> <title>Paradox: Thermodynamic equilibrium does not exist in gravitational fields</title> <pubDate>Mon, 17 Feb 2025 11:24:05 +0000</pubDate> <link>https://www.physicsforums.com/threads/paradox-thermodynamic-equilibrium-does-not-exist-in-gravitational-fields.1066682/</link> <guid isPermaLink="false">1066682</guid> <author>invalid@example.com (Petr Matas)</author> <category domain="https://www.physicsforums.com/forums/thermodynamics.301/"><![CDATA[Thermodynamics]]></category> <dc:creator>Petr Matas</dc:creator> <content:encoded><![CDATA[<div class="bbWrapper">I&#039;ve come across a paradox I can&#039;t resolve.<br /> <br /> Let&#039;s have an isolated system: A gas in a box in a homogeneous gravitational field. When thermodynamic equilibrium is reached, the gas should have an adiabatic temperature gradient (temperature decreases with increasing height). The walls are in...<br /> <br /> <a href="https://www.physicsforums.com/threads/paradox-thermodynamic-equilibrium-does-not-exist-in-gravitational-fields.1066682/" class="link link--internal">Read more</a></div>]]></content:encoded> <slash:comments>134</slash:comments> </item> <item> <title>LED Detection Range with Night Vision Goggles?</title> <pubDate>Mon, 17 Feb 2025 05:43:25 +0000</pubDate> <link>https://www.physicsforums.com/threads/led-detection-range-with-night-vision-goggles.1078592/</link> <guid isPermaLink="false">1078592</guid> <author>invalid@example.com (r971821)</author> <category domain="https://www.physicsforums.com/forums/optics.300/"><![CDATA[Optics]]></category> <dc:creator>r971821</dc:creator> <content:encoded><![CDATA[<div class="bbWrapper">Hi:<br /> Non-physicist here doing some research into detection ability of LED wavelengths by Gen3 anvis9 NVG. Have found that these NVG&#039;s optimize 600-900nm. Since LED are sold and measured in K, the conversion is not directly evident to me. <br /> Is it possible to create a chart that might show where the...<br /> <br /> <a href="https://www.physicsforums.com/threads/led-detection-range-with-night-vision-goggles.1078592/" class="link link--internal">Read more</a></div>]]></content:encoded> <slash:comments>1</slash:comments> </item> <item> <title>Correct statement about light transmitted and reflected by windscreen</title> <pubDate>Mon, 17 Feb 2025 05:42:26 +0000</pubDate> <link>https://www.physicsforums.com/threads/correct-statement-about-light-transmitted-and-reflected-by-windscreen.1078317/</link> <guid isPermaLink="false">1078317</guid> <author>invalid@example.com (songoku)</author> <category domain="https://www.physicsforums.com/forums/introductory-physics-homework-help.153/"><![CDATA[Introductory Physics Homework Help]]></category> <dc:creator>songoku</dc:creator> <content:encoded><![CDATA[<div class="bbWrapper"><img src="https://www.physicsforums.com/attachments/1738294278965-png.356635/" class="bbImage " style="width: 495px" alt="1738294278965.png" title="1738294278965.png" width="543" height="492" loading="lazy" /><br /> <br /> I don&#039;t really understand how to relate the question to the picture. Picture Y is taken using polarising filter but how can we know whether it is light transmitted or reflected because I think in both pictures there is light transmitted through the windscreen and there is also...<br /> <br /> <a href="https://www.physicsforums.com/threads/correct-statement-about-light-transmitted-and-reflected-by-windscreen.1078317/" class="link link--internal">Read more</a></div>]]></content:encoded> <slash:comments>11</slash:comments> </item> <item> <title>Basic question about RLC circuits</title> <pubDate>Mon, 17 Feb 2025 05:32:26 +0000</pubDate> <link>https://www.physicsforums.com/threads/basic-question-about-rlc-circuits.1078562/</link> <guid isPermaLink="false">1078562</guid> <author>invalid@example.com (Malamala)</author> <category domain="https://www.physicsforums.com/forums/electrical-engineering.102/"><![CDATA[Electrical Engineering]]></category> <dc:creator>Malamala</dc:creator> <content:encoded><![CDATA[<div class="bbWrapper">I am really new to this so please let me know if I am doing anything wrong. I have an RLC circuit which contains a capacitor with ##C = 0.1## nF. I need to drive it resonantly at ##\omega_0 = 2\pi\times 100## MHz and I want the voltage across the capacitor to be ##V_C = 500## V. In this case the...<br /> <br /> <a href="https://www.physicsforums.com/threads/basic-question-about-rlc-circuits.1078562/" class="link link--internal">Read more</a></div>]]></content:encoded> <slash:comments>16</slash:comments> </item> <item> <title>Design of interrupt handling hardware circuit for a real time scenario</title> <pubDate>Mon, 17 Feb 2025 04:24:37 +0000</pubDate> <link>https://www.physicsforums.com/threads/design-of-interrupt-handling-hardware-circuit-for-a-real-time-scenario.1078539/</link> <guid isPermaLink="false">1078539</guid> <author>invalid@example.com (brainbaby)</author> <category domain="https://www.physicsforums.com/forums/programming-and-computer-science.165/"><![CDATA[Programming and Computer Science]]></category> <dc:creator>brainbaby</dc:creator> <content:encoded><![CDATA[<div class="bbWrapper"><b> Implementing interrupt handling mechanism using interrupt vector table for a daily life (real time) example.</b><br /> <br /> I want to design a hardware which implements a logic of accessing books from a library system.<br /> The library system contains 3 shelves, 3 racks on each shelf, &amp; some books.<br /> The aim...<br /> <br /> <a href="https://www.physicsforums.com/threads/design-of-interrupt-handling-hardware-circuit-for-a-real-time-scenario.1078539/" class="link link--internal">Read more</a></div>]]></content:encoded> <slash:comments>14</slash:comments> </item> <item> <title>Sow the phase and Reap the sin -- why?</title> <pubDate>Mon, 17 Feb 2025 04:15:30 +0000</pubDate> <link>https://www.physicsforums.com/threads/sow-the-phase-and-reap-the-sin-why.1078613/</link> <guid isPermaLink="false">1078613</guid> <author>invalid@example.com (Swamp Thing)</author> <category domain="https://www.physicsforums.com/forums/matlab-maple-mathematica-latex.189/"><![CDATA[MATLAB, Maple, Mathematica, LaTeX]]></category> <dc:creator>Swamp Thing</dc:creator> <content:encoded><![CDATA[<div class="bbWrapper">Mathematica code :<br /> <br /> <div class="bbCodeBlock bbCodeBlock--screenLimited bbCodeBlock--code noLang " data-xf-init="CMTV-code-block"> <div class="bbCodeBlock-header"> <div class="bbCodeBlock-title"> <span title=""> Code: </span> </div> <div class="bbCodeBlock-actions"> <i class="fa--xf fal fa-expand-alt action action--expand action--hidden" aria-hidden="true" title="Expand" data-xf-init="tooltip" data-xf-click="CMTV-code-block-expand"></i> <i class="fa--xf fal fa-compress-alt action action--collapse action--hidden" aria-hidden="true" title="Collapse" data-xf-init="tooltip" data-xf-click="CMTV-code-block-collapse"></i> <i class="fa--xf fal fa-paste action action--copy" aria-hidden="true" title="Copy" data-xf-init="tooltip"></i> </div> </div> <div class="bbCodeBlock-content" dir="ltr"> <pre class="bbCodeCode line-numbers language-none" dir="ltr" data-line="" data-xf-init="CMTV-code-block-extend" data-lang=""><code>Reap[ ( sin = ( ( phase = 2 Pi #/32; Sow[phase]; Sin[phase] ) &amp; /@ Range[32] ) ) ]</code></pre> </div> <div class="bbCodeBlock-grip resizer--hidden" data-xf-init="CMTV-code-block-resizer"> <i class="fa--xf fal fa-grip-horizontal" aria-hidden="true"></i> </div> </div><br /> The output looks like this:<br /> <img src="https://www.physicsforums.com/attachments/1739760534140-png.357409/" class="bbImage " style="" alt="1739760534140.png" title="1739760534140.png" width="783" height="319" loading="lazy" /><br /> <br /> <br /> But I would...<br /> <br /> <a href="https://www.physicsforums.com/threads/sow-the-phase-and-reap-the-sin-why.1078613/" class="link link--internal">Read more</a></div>]]></content:encoded> <slash:comments>2</slash:comments> </item> <item> <title>Does anyone know what this electric hacksaw is called?</title> <pubDate>Mon, 17 Feb 2025 03:55:29 +0000</pubDate> <link>https://www.physicsforums.com/threads/does-anyone-know-what-this-electric-hacksaw-is-called.1078597/</link> <guid isPermaLink="false">1078597</guid> <author>invalid@example.com (tirelessphoenix)</author> <category domain="https://www.physicsforums.com/forums/diy-projects.264/"><![CDATA[DIY Projects]]></category> <dc:creator>tirelessphoenix</dc:creator> <content:encoded><![CDATA[<div class="bbWrapper">Does anyone know how this electric hacksaw is called? I attach the video that shows how it is used.<br /> <br /> <span data-s9e-mediaembed="youtube"><span><iframe allowfullscreen="" scrolling="no" allow="autoplay" style="background:linear-gradient(0deg,rgba(0,0,0,0) 0,rgba(0,0,0,0) 72%,rgba(0,0,0,.04) 79%,rgba(0,0,0,.1) 83%,rgba(0,0,0,.25) 88%,rgba(0,0,0,.67) 100%),url(https://i.ytimg.com/vi/HlsRkr0a9jo/hqdefault.jpg) 50% 50% / cover" src="https://www.youtube.com/embed/HlsRkr0a9jo" data-s9e-mediaembed-c2l="youtube" data-s9e-mediaembed-c2l-oembed-id="HlsRkr0a9jo" data-s9e-mediaembed-c2l-src="https://www.youtube.com/embed/HlsRkr0a9jo?autoplay=1"></iframe></span></span><br /> <br /> Thank you<br /> d.</div>]]></content:encoded> <slash:comments>5</slash:comments> </item> <item> <title>Electronic Keyboard Goes Out Of Tune</title> <pubDate>Mon, 17 Feb 2025 03:20:00 +0000</pubDate> <link>https://www.physicsforums.com/threads/electronic-keyboard-goes-out-of-tune.1078190/</link> <guid isPermaLink="false">1078190</guid> <author>invalid@example.com (Hornbein)</author> <category domain="https://www.physicsforums.com/forums/electrical-engineering.102/"><![CDATA[Electrical Engineering]]></category> <dc:creator>Hornbein</dc:creator> <content:encoded><![CDATA[<div class="bbWrapper">One of my Yamaha electronic keyboards has gone out of tune. It&#039;s 1% flat. It&#039;s not a problem -- I just tune it up so I&#039;m not looking for a cure-- the point is I&#039;m surprised that this is possible. I thought digital musical devices couldn&#039;t go out of tune.</div>]]></content:encoded> <slash:comments>10</slash:comments> </item> <item> <title>Need help wiring a motor switch</title> <pubDate>Mon, 17 Feb 2025 02:01:36 +0000</pubDate> <link>https://www.physicsforums.com/threads/need-help-wiring-a-motor-switch.1078571/</link> <guid isPermaLink="false">1078571</guid> <author>invalid@example.com (gmax137)</author> <category domain="https://www.physicsforums.com/forums/electrical-engineering.102/"><![CDATA[Electrical Engineering]]></category> <dc:creator>gmax137</dc:creator> <content:encoded><![CDATA[<div class="bbWrapper">I&#039;m replacing the motor on my old Logan lathe. The old motor was pretty simple, it had four wires; two to run and two for the starting coil. I can&#039;t seem to figure out how to wire up the reversing switch for the new motor. Here&#039;s the plate on the new motor. <br /> <img src="https://www.physicsforums.com/attachments/motor_plate_crop-jpg.357309/" class="bbImage " style="" alt="motor_plate_crop.jpg" title="motor_plate_crop.jpg" width="573" height="620" loading="lazy" /><br /> <br /> The drum switch I...<br /> <br /> <a href="https://www.physicsforums.com/threads/need-help-wiring-a-motor-switch.1078571/" class="link link--internal">Read more</a></div>]]></content:encoded> <slash:comments>8</slash:comments> </item> <item> <title>Cover songs versus the original track, which ones are better?</title> <pubDate>Mon, 17 Feb 2025 01:39:28 +0000</pubDate> <link>https://www.physicsforums.com/threads/cover-songs-versus-the-original-track-which-ones-are-better.1050205/</link> <guid isPermaLink="false">1050205</guid> <author>invalid@example.com (pinball1970)</author> <category domain="https://www.physicsforums.com/forums/art-music-history-and-linguistics.20/"><![CDATA[Art, Music, History, and Linguistics]]></category> <dc:creator>pinball1970</dc:creator> <content:encoded><![CDATA[<div class="bbWrapper">Which songs were performed, arranged or produced better in a cover than the original version?<br /> Which songs should have been left well alone? <br /> <br /> Also, I think restricting the covers just to released singles will restrict some interesting stonkers and stinkers so album tracks are allowed.</div>]]></content:encoded> <slash:comments>1686</slash:comments> </item> <item> <title>Force pulling on a string at an angle with a block at the other end</title> <pubDate>Mon, 17 Feb 2025 01:06:21 +0000</pubDate> <link>https://www.physicsforums.com/threads/force-pulling-on-a-string-at-an-angle-with-a-block-at-the-other-end.1078609/</link> <guid isPermaLink="false">1078609</guid> <author>invalid@example.com (kekpillangok)</author> <category domain="https://www.physicsforums.com/forums/introductory-physics-homework-help.153/"><![CDATA[Introductory Physics Homework Help]]></category> <dc:creator>kekpillangok</dc:creator> <content:encoded><![CDATA[<div class="bbWrapper">I can&#039;t understand what is going on here. My intuition tells me that the traction pulling on the block should be equal to F. Apparently, however, the problem would have me believe that this is not the case, as it gives me a 30° angle at which the force acts and a 6-8-10 triangle as ways to...<br /> <br /> <a href="https://www.physicsforums.com/threads/force-pulling-on-a-string-at-an-angle-with-a-block-at-the-other-end.1078609/" class="link link--internal">Read more</a></div>]]></content:encoded> <slash:comments>2</slash:comments> </item> <item> <title>Physical Meaning of Atomic Oscillations</title> <pubDate>Mon, 17 Feb 2025 00:40:06 +0000</pubDate> <link>https://www.physicsforums.com/threads/physical-meaning-of-atomic-oscillations.1078520/</link> <guid isPermaLink="false">1078520</guid> <author>invalid@example.com (Sciencemaster)</author> <category domain="https://www.physicsforums.com/forums/quantum-physics.62/"><![CDATA[Quantum Physics]]></category> <dc:creator>Sciencemaster</dc:creator> <content:encoded><![CDATA[<div class="bbWrapper">A physics question for those more atomically inclined than myself. Atomic clocks are said to measure the frequency of oscillations. By this definition of atomic oscillation, is anything physically vibrating, or does it just mean switching between the two energy levels without excess explicit...<br /> <br /> <a href="https://www.physicsforums.com/threads/physical-meaning-of-atomic-oscillations.1078520/" class="link link--internal">Read more</a></div>]]></content:encoded> <slash:comments>11</slash:comments> </item> <item> <title>Global Warming, History of Earth's Temperature</title> <pubDate>Sun, 16 Feb 2025 22:58:38 +0000</pubDate> <link>https://www.physicsforums.com/threads/global-warming-history-of-earths-temperature.1067619/</link> <guid isPermaLink="false">1067619</guid> <author>invalid@example.com (Tom.G)</author> <category domain="https://www.physicsforums.com/forums/earth-sciences.84/"><![CDATA[Earth Sciences]]></category> <dc:creator>Tom.G</dc:creator> <content:encoded><![CDATA[<div class="bbWrapper">According to this study published in <i>Science</i> magazine, the Earth hasn&#039;t been this cold for the past 350-450 million years. The Global Mean Surface Temperature took a dive about 40mya from 27C to the current 11C.<br /> <img src="https://www.physicsforums.com/attachments/1739421785796-jpeg.357233/" class="bbImage " style="" alt="1739421785796.jpeg" title="1739421785796.jpeg" width="800" height="290" loading="lazy" /><br /> It seems like we are in the &#039;Golden Age&#039; for warm-blooded...<br /> <br /> <a href="https://www.physicsforums.com/threads/global-warming-history-of-earths-temperature.1067619/" class="link link--internal">Read more</a></div>]]></content:encoded> <slash:comments>57</slash:comments> </item> <item> <title>New theorem</title> <pubDate>Sun, 16 Feb 2025 21:44:27 +0000</pubDate> <link>https://www.physicsforums.com/threads/new-theorem.1078604/</link> <guid isPermaLink="false">1078604</guid> <author>invalid@example.com (zuz)</author> <category domain="https://www.physicsforums.com/forums/general-math.73/"><![CDATA[General Math]]></category> <dc:creator>zuz</dc:creator> <content:encoded><![CDATA[<div class="bbWrapper">a-1 x a+1= a squared-1 Is this an established theorem or have I stumbled onto something that might get my name in the math books?</div>]]></content:encoded> <slash:comments>9</slash:comments> </item> <item> <title>I don't understand how the author calculated the pullback of the 1 form (differential geometry)</title> <pubDate>Sun, 16 Feb 2025 21:15:07 +0000</pubDate> <link>https://www.physicsforums.com/threads/i-dont-understand-how-the-author-calculated-the-pullback-of-the-1-form-differential-geometry.1078536/</link> <guid isPermaLink="false">1078536</guid> <author>invalid@example.com (DiffMani)</author> <category domain="https://www.physicsforums.com/forums/calculus-and-beyond-homework-help.156/"><![CDATA[Calculus and Beyond Homework Help]]></category> <dc:creator>DiffMani</dc:creator> <content:encoded><![CDATA[<div class="bbWrapper">I am doing self study on differential geometry using Analysis and Algebra on Differentiable Manifolds by Gadea. I don&#039;t understand the step where he calculates the pullback of the left translation of the one form. Why did all the variables become x? What is the formula for the pullback on w?<br /> I...<br /> <br /> <a href="https://www.physicsforums.com/threads/i-dont-understand-how-the-author-calculated-the-pullback-of-the-1-form-differential-geometry.1078536/" class="link link--internal">Read more</a></div>]]></content:encoded> <slash:comments>5</slash:comments> </item> <item> <title>Allegations of AI misuse in PF</title> <pubDate>Sun, 16 Feb 2025 20:48:47 +0000</pubDate> <link>https://www.physicsforums.com/threads/allegations-of-ai-misuse-in-pf.1078512/</link> <guid isPermaLink="false">1078512</guid> <author>invalid@example.com (pines-demon)</author> <category domain="https://www.physicsforums.com/forums/feedback-and-announcements.19/"><![CDATA[Feedback and Announcements]]></category> <dc:creator>pines-demon</dc:creator> <content:encoded><![CDATA[<div class="bbWrapper">I just found out this blogpost:<br /> <ul> <li data-xf-list-type="ul"><a href="https://hallofdreams.org/posts/physicsforums/" target="_blank" class="link link--external" rel="nofollow ugc noopener">PhysicsForums and the Dead Internet Theory</a>, Hall of Impossible Dreams (2025)</li> </ul>where some bloggers revise some old posts in PF and show evidence of dead accounts being recycled by AI bots. The article does not put the blame on anybody directly (Greg...<br /> <br /> <a href="https://www.physicsforums.com/threads/allegations-of-ai-misuse-in-pf.1078512/" class="link link--internal">Read more</a></div>]]></content:encoded> <slash:comments>13</slash:comments> </item> <item> <title>Does a "physically real" quantum interpretation exist?</title> <pubDate>Sun, 16 Feb 2025 18:13:39 +0000</pubDate> <link>https://www.physicsforums.com/threads/does-a-physically-real-quantum-interpretation-exist.1078505/</link> <guid isPermaLink="false">1078505</guid> <author>invalid@example.com (timmdeeg)</author> <category domain="https://www.physicsforums.com/forums/quantum-interpretations-and-foundations.292/"><![CDATA[Quantum Interpretations and Foundations]]></category> <dc:creator>timmdeeg</dc:creator> <content:encoded><![CDATA[<div class="bbWrapper">There are several interpretations of quantum mechanics, most of which are in contradiction to each other, e.g. whether or not the wave function collapses, is ontic, has to be understood in the instrumentalist&#039;s view and so forth.<br /> <br /> My question refers to the meaning of the term &quot;interpretation&quot;...<br /> <br /> <a href="https://www.physicsforums.com/threads/does-a-physically-real-quantum-interpretation-exist.1078505/" class="link link--internal">Read more</a></div>]]></content:encoded> <slash:comments>62</slash:comments> </item> <item> <title>"Proof" of Born rule by principle of indifference</title> <pubDate>Sun, 16 Feb 2025 17:39:02 +0000</pubDate> <link>https://www.physicsforums.com/threads/proof-of-born-rule-by-principle-of-indifference.1078564/</link> <guid isPermaLink="false">1078564</guid> <author>invalid@example.com (greypilgrim)</author> <category domain="https://www.physicsforums.com/forums/quantum-interpretations-and-foundations.292/"><![CDATA[Quantum Interpretations and Foundations]]></category> <dc:creator>greypilgrim</dc:creator> <content:encoded><![CDATA[<div class="bbWrapper">Hi.<br /> <br /> In <a href="https://www.youtube.com/watch?v=cKlRnutiv-k" target="_blank" class="link link--external" rel="nofollow ugc noopener">this video</a> of <a href="https://www.youtube.com/@LookingGlassUniverse" target="_blank" class="link link--external" rel="nofollow ugc noopener">Looking Glass Universe</a>, the host &quot;proves&quot; the Born rule by breaking down states into &quot;finer&quot; ones and then applying the principle of indifference. In the description, she bases this on papers by Deutsch, Hossenfelder, Zurek and Hardy. I have never heard of this...<br /> <br /> <a href="https://www.physicsforums.com/threads/proof-of-born-rule-by-principle-of-indifference.1078564/" class="link link--internal">Read more</a></div>]]></content:encoded> <slash:comments>3</slash:comments> </item> <item> <title>Is there a link between poultry consumption and longevity?</title> <pubDate>Sun, 16 Feb 2025 17:19:45 +0000</pubDate> <link>https://www.physicsforums.com/threads/is-there-a-link-between-poultry-consumption-and-longevity.1066727/</link> <guid isPermaLink="false">1066727</guid> <author>invalid@example.com (Spathi)</author> <category domain="https://www.physicsforums.com/forums/biology-and-medical.82/"><![CDATA[Biology and Medical]]></category> <dc:creator>Spathi</dc:creator> <content:encoded><![CDATA[<div class="bbWrapper">There is some evidence that the vegetarians live longer that people who eat meat:<br /> <br /> <a href="https://www.sciencedirect.com/science/article/pii/S0002916522033524" target="_blank" class="link link--external" rel="nofollow ugc noopener">https://www.sciencedirect.com/science/article/pii/S0002916522033524</a><br /> <br /> <blockquote data-attributes="" data-quote="" data-source="" class="bbCodeBlock bbCodeBlock--expandable bbCodeBlock--quote js-expandWatch"> <div class="bbCodeBlock-content"> <div class="bbCodeBlock-expandContent js-expandContent "> <i>1</i>) a very low meat intake was associated with a significant decrease in risk of death in 4 studies, a nonsignificant decrease in... </div> </div> </blockquote><br /> <a href="https://www.physicsforums.com/threads/is-there-a-link-between-poultry-consumption-and-longevity.1066727/" class="link link--internal">Read more</a></div>]]></content:encoded> <slash:comments>28</slash:comments> </item> <item> <title>Involuntary "upgrade" Windows Mail app to Outlook</title> <pubDate>Sun, 16 Feb 2025 15:11:13 +0000</pubDate> <link>https://www.physicsforums.com/threads/involuntary-upgrade-windows-mail-app-to-outlook.1078583/</link> <guid isPermaLink="false">1078583</guid> <author>invalid@example.com (sandy stone)</author> <category domain="https://www.physicsforums.com/forums/computing-and-technology.188/"><![CDATA[Computing and Technology]]></category> <dc:creator>sandy stone</dc:creator> <content:encoded><![CDATA[<div class="bbWrapper">This morning when I woke up my computer I found that the Windows Mail app had disappeared and the new Outlook had taken its place, without any input from me. Now, in order to use Outlook and get access to my emails, Microsoft insists that I route all my emails through their cloud servers. Why...<br /> <br /> <a href="https://www.physicsforums.com/threads/involuntary-upgrade-windows-mail-app-to-outlook.1078583/" class="link link--internal">Read more</a></div>]]></content:encoded> <slash:comments>6</slash:comments> </item> <item> <title>At what age is special relativity taught?</title> <pubDate>Sun, 16 Feb 2025 14:59:35 +0000</pubDate> <link>https://www.physicsforums.com/threads/at-what-age-is-special-relativity-taught.1078515/</link> <guid isPermaLink="false">1078515</guid> <author>invalid@example.com (Trysse)</author> <category domain="https://www.physicsforums.com/forums/stem-educators-and-teaching.192/"><![CDATA[STEM Educators and Teaching]]></category> <dc:creator>Trysse</dc:creator> <content:encoded><![CDATA[<div class="bbWrapper">This is a question to school teachers (and all those who know about physics syllabus at school).<br /> <br /> Is relativity (special and or general) taught in school (pre university) in your country?<br /> <br /> If yes, at what age are students introduced to relativity? What aspects are taught?<br /> <br /> As far as I remember...<br /> <br /> <a href="https://www.physicsforums.com/threads/at-what-age-is-special-relativity-taught.1078515/" class="link link--internal">Read more</a></div>]]></content:encoded> <slash:comments>18</slash:comments> </item> <item> <title>Confusion about friction in rotating ring</title> <pubDate>Sun, 16 Feb 2025 13:17:17 +0000</pubDate> <link>https://www.physicsforums.com/threads/confusion-about-friction-in-rotating-ring.1078601/</link> <guid isPermaLink="false">1078601</guid> <author>invalid@example.com (palaphys)</author> <category domain="https://www.physicsforums.com/forums/introductory-physics-homework-help.153/"><![CDATA[Introductory Physics Homework Help]]></category> <dc:creator>palaphys</dc:creator> <content:encoded><![CDATA[<div class="bbWrapper">So to begin with, I did this:<br /> <br /> $$<br /> <br /> <br /> \begin{align*}<br /> dm &amp;= \frac{M}{2\pi} d\theta \\ <br /> dN &amp;= dm \cdot g = \frac{M}{2\pi} g \, d\theta \\ <br /> df &amp;= \mu_k \, dN = \mu_k \frac{M}{2\pi} g \, d\theta \\ <br /> f &amp;= \int df = \int_0^{2\pi} \mu_k \frac{M}{2\pi} g \, d\theta \\ <br /> f &amp;= \mu_k \frac{M}{2\pi} g...<br /> <br /> <a href="https://www.physicsforums.com/threads/confusion-about-friction-in-rotating-ring.1078601/" class="link link--internal">Read more</a></div>]]></content:encoded> <slash:comments>12</slash:comments> </item> <item> <title>Movable Wall in an Adiabatic System: Same Final Temperature?</title> <pubDate>Sun, 16 Feb 2025 12:10:59 +0000</pubDate> <link>https://www.physicsforums.com/threads/movable-wall-in-an-adiabatic-system-same-final-temperature.1078581/</link> <guid isPermaLink="false">1078581</guid> <author>invalid@example.com (Filipeml)</author> <category domain="https://www.physicsforums.com/forums/thermodynamics.301/"><![CDATA[Thermodynamics]]></category> <dc:creator>Filipeml</dc:creator> <content:encoded><![CDATA[<div class="bbWrapper">Consider an adiabatic container divided into two chambers by a movable, heat-conducting wall. One side contains a monatomic ideal gas, while the other contains a diatomic ideal gas. Initially, both gases are at the same temperature and pressure. Over time, the wall moves until a new...<br /> <br /> <a href="https://www.physicsforums.com/threads/movable-wall-in-an-adiabatic-system-same-final-temperature.1078581/" class="link link--internal">Read more</a></div>]]></content:encoded> <slash:comments>3</slash:comments> </item> <item> <title>Space Stuff and Launch Info</title> <pubDate>Sun, 16 Feb 2025 10:48:13 +0000</pubDate> <link>https://www.physicsforums.com/threads/space-stuff-and-launch-info.879196/</link> <guid isPermaLink="false">879196</guid> <author>invalid@example.com (1oldman2)</author> <category domain="https://www.physicsforums.com/forums/aerospace-engineering.288/"><![CDATA[Aerospace Engineering]]></category> <dc:creator>1oldman2</dc:creator> <content:encoded><![CDATA[<div class="bbWrapper">Due to the constant never ending supply of &quot;cool stuff&quot; happening in Aerospace these days I&#039;m creating this thread to consolidate posts every time something new comes along. Please feel free to add random information if its relevant. So to start things off here is the SpaceX Dragon launch coming...<br /> <br /> <a href="https://www.physicsforums.com/threads/space-stuff-and-launch-info.879196/" class="link link--internal">Read more</a></div>]]></content:encoded> <slash:comments>1465</slash:comments> </item> <item> <title>Trying To Run Python Code</title> <pubDate>Sun, 16 Feb 2025 09:59:46 +0000</pubDate> <link>https://www.physicsforums.com/threads/trying-to-run-python-code.1078600/</link> <guid isPermaLink="false">1078600</guid> <author>invalid@example.com (Hornbein)</author> <category domain="https://www.physicsforums.com/forums/programming-and-computer-science.165/"><![CDATA[Programming and Computer Science]]></category> <dc:creator>Hornbein</dc:creator> <content:encoded><![CDATA[<div class="bbWrapper">I have some Python code I wrote and ran in 2021. I&#039;m trying to run it again. I have a computer I bought in 2024 running Windows 11.<br /> <br /> I used to run under Anaconda. I downloaded that. Attempts to run Spyder, the Python IDE, failed. It wouldn&#039;t execute.<br /> <br /> So I downloaded Spyder and Python. I...<br /> <br /> <a href="https://www.physicsforums.com/threads/trying-to-run-python-code.1078600/" class="link link--internal">Read more</a></div>]]></content:encoded> <slash:comments>1</slash:comments> </item> <item> <title>Is this a finite arguement of the countably infiniteness of the rationals?</title> <pubDate>Sun, 16 Feb 2025 09:59:18 +0000</pubDate> <link>https://www.physicsforums.com/threads/is-this-a-finite-arguement-of-the-countably-infiniteness-of-the-rationals.1078595/</link> <guid isPermaLink="false">1078595</guid> <author>invalid@example.com (mcastillo356)</author> <category domain="https://www.physicsforums.com/forums/set-theory-logic-probability-statistics.78/"><![CDATA[Set Theory, Logic, Probability, Statistics]]></category> <dc:creator>mcastillo356</dc:creator> <content:encoded><![CDATA[<div class="bbWrapper">Hi, PF<br /> <br /> <b>Theorem</b><br /> The set ##\mathbb{Q}## of the rational numbers is countably infinite.<br /> <br /> <b>Proof</b><br /> The rational numbers are arranged thus...<br /> <br /> <a href="https://www.physicsforums.com/threads/is-this-a-finite-arguement-of-the-countably-infiniteness-of-the-rationals.1078595/" class="link link--internal">Read more</a></div>]]></content:encoded> <slash:comments>2</slash:comments> </item> <item> <title>Problem n. 7 chapter 4 Eisberg Resnick "Quantum Physics"</title> <pubDate>Sun, 16 Feb 2025 08:01:39 +0000</pubDate> <link>https://www.physicsforums.com/threads/problem-n-7-chapter-4-eisberg-resnick-quantum-physics.1078566/</link> <guid isPermaLink="false">1078566</guid> <author>invalid@example.com (baffetto59)</author> <category domain="https://www.physicsforums.com/forums/introductory-physics-homework-help.153/"><![CDATA[Introductory Physics Homework Help]]></category> <dc:creator>baffetto59</dc:creator> <content:encoded><![CDATA[<div class="bbWrapper">a</div>]]></content:encoded> <slash:comments>9</slash:comments> </item> <item> <title>Question about the EOM used for PDH locking</title> <pubDate>Sun, 16 Feb 2025 05:09:59 +0000</pubDate> <link>https://www.physicsforums.com/threads/question-about-the-eom-used-for-pdh-locking.1078599/</link> <guid isPermaLink="false">1078599</guid> <author>invalid@example.com (Malamala)</author> <category domain="https://www.physicsforums.com/forums/atomic-and-condensed-matter.64/"><![CDATA[Atomic and Condensed Matter]]></category> <dc:creator>Malamala</dc:creator> <content:encoded><![CDATA[<div class="bbWrapper">Hello! I am locking a ~30 kHz linewidth laser to a ~100 kHz linewidth ultrastable (ULE) cavity, aiming to reduce the laser linewidth to ~ 1 kHz using PHD locking. The feedback signal is sent to the laser current (it is an external cavity diode laser). For PDH the modulation of the EOM used to...<br /> <br /> <a href="https://www.physicsforums.com/threads/question-about-the-eom-used-for-pdh-locking.1078599/" class="link link--internal">Read more</a></div>]]></content:encoded> <slash:comments>0</slash:comments> </item> <item> <title>Rendering an .OBJ as a 3D interactive display</title> <pubDate>Sun, 16 Feb 2025 03:57:24 +0000</pubDate> <link>https://www.physicsforums.com/threads/rendering-an-obj-as-a-3d-interactive-display.1078382/</link> <guid isPermaLink="false">1078382</guid> <author>invalid@example.com (DaveC426913)</author> <category domain="https://www.physicsforums.com/forums/computing-and-technology.188/"><![CDATA[Computing and Technology]]></category> <dc:creator>DaveC426913</dc:creator> <content:encoded><![CDATA[<div class="bbWrapper">Welp. I&#039;ve been given a challenge to help out with a project. I have no budget, no knowledge-holders and not much knowledge, but I&#039;ll see how far I can get.<br /> <br /> I am about to receive an .OBJ file of a critter. I have some experience in Blender, building and shaping and stuff (not a super complex...<br /> <br /> <a href="https://www.physicsforums.com/threads/rendering-an-obj-as-a-3d-interactive-display.1078382/" class="link link--internal">Read more</a></div>]]></content:encoded> <slash:comments>13</slash:comments> </item> <item> <title>A block dropping onto a spring system</title> <pubDate>Sun, 16 Feb 2025 02:13:39 +0000</pubDate> <link>https://www.physicsforums.com/threads/a-block-dropping-onto-a-spring-system.1078558/</link> <guid isPermaLink="false">1078558</guid> <author>invalid@example.com (palaphys)</author> <category domain="https://www.physicsforums.com/forums/introductory-physics-homework-help.153/"><![CDATA[Introductory Physics Homework Help]]></category> <dc:creator>palaphys</dc:creator> <content:encoded><![CDATA[<div class="bbWrapper">Consider this situation. A mass $$m$$ is dropped onto the spring system from rest , and it is given that the smaller spring gets compressed by a distance $$h$$<br /> <br /> My main query in this question is regarding the use of Work Energy theorem, which states that the work done on a body by all the forces...<br /> <br /> <a href="https://www.physicsforums.com/threads/a-block-dropping-onto-a-spring-system.1078558/" class="link link--internal">Read more</a></div>]]></content:encoded> <slash:comments>58</slash:comments> </item> <item> <title>High energy tritons</title> <pubDate>Sun, 16 Feb 2025 02:06:16 +0000</pubDate> <link>https://www.physicsforums.com/threads/high-energy-tritons.1078580/</link> <guid isPermaLink="false">1078580</guid> <author>invalid@example.com (snorkack)</author> <category domain="https://www.physicsforums.com/forums/high-energy-nuclear-particle-physics.65/"><![CDATA[High Energy, Nuclear, Particle Physics]]></category> <dc:creator>snorkack</dc:creator> <content:encoded><![CDATA[<div class="bbWrapper">Cosmic rays are well attested to include particles with energies above 100 EeV. Three most energetic rays observed have been OMG particle (320 EeV, in 1991), an unnamed particle in 2001 (280 EeV) and Amaterasu particle in 2021 (240 EeV).<br /> Pierre Auger observatory has seen 100 particles over 78...<br /> <br /> <a href="https://www.physicsforums.com/threads/high-energy-tritons.1078580/" class="link link--internal">Read more</a></div>]]></content:encoded> <slash:comments>2</slash:comments> </item> <item> <title>COBOL and MUSKateers</title> <pubDate>Sun, 16 Feb 2025 01:15:45 +0000</pubDate> <link>https://www.physicsforums.com/threads/cobol-and-muskateers.1078589/</link> <guid isPermaLink="false">1078589</guid> <author>invalid@example.com (hutchphd)</author> <category domain="https://www.physicsforums.com/forums/programming-and-computer-science.165/"><![CDATA[Programming and Computer Science]]></category> <dc:creator>hutchphd</dc:creator> <content:encoded><![CDATA[<div class="bbWrapper">Calling all COBOL geeks........<br /> <br /> I have never used COBOL. I wonder about the latest claims of waste fraud and abuse made by Trump/Musk about 150 yr old recipients of government largesse. Talking heads claim that, in fact, COBOL actually<br /> defaults birthdates to 1875 as an error code . I would...<br /> <br /> <a href="https://www.physicsforums.com/threads/cobol-and-muskateers.1078589/" class="link link--internal">Read more</a></div>]]></content:encoded> <slash:comments>6</slash:comments> </item> <item> <title>Would gravitons theoretically act like photons?</title> <pubDate>Sun, 16 Feb 2025 00:46:14 +0000</pubDate> <link>https://www.physicsforums.com/threads/would-gravitons-theoretically-act-like-photons.1078457/</link> <guid isPermaLink="false">1078457</guid> <author>invalid@example.com (Josiah)</author> <category domain="https://www.physicsforums.com/forums/quantum-physics.62/"><![CDATA[Quantum Physics]]></category> <dc:creator>Josiah</dc:creator> <content:encoded><![CDATA[<div class="bbWrapper">Hi, would gravitons theoretically act like photons? They&#039;re both particles and waves at the same time. Is there anything we can use from what we know about photons and use them to understand gravitons?<br /> Thanks<br /> Josiah</div>]]></content:encoded> <slash:comments>7</slash:comments> </item> <item> <title>Weird News Compilation</title> <pubDate>Sun, 16 Feb 2025 00:08:56 +0000</pubDate> <link>https://www.physicsforums.com/threads/weird-news-compilation.878428/</link> <guid isPermaLink="false">878428</guid> <author>invalid@example.com (Evo)</author> <category domain="https://www.physicsforums.com/forums/general-discussion.14/"><![CDATA[General Discussion]]></category> <dc:creator>Evo</dc:creator> <content:encoded><![CDATA[<div class="bbWrapper">I&#039;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.<br /> <br /> Turns out that Zoobyshoe beat me in posting about this in another thread, so he will officially be known...<br /> <br /> <a href="https://www.physicsforums.com/threads/weird-news-compilation.878428/" class="link link--internal">Read more</a></div>]]></content:encoded> <slash:comments>1999</slash:comments> </item> <item> <title>Paper 'helicopter' experiment - Adding Weight Decreases Flight Time?</title> <pubDate>Sat, 15 Feb 2025 23:41:59 +0000</pubDate> <link>https://www.physicsforums.com/threads/paper-helicopter-experiment-adding-weight-decreases-flight-time.1078521/</link> <guid isPermaLink="false">1078521</guid> <author>invalid@example.com (Mahid)</author> <category domain="https://www.physicsforums.com/forums/introductory-physics-homework-help.153/"><![CDATA[Introductory Physics Homework Help]]></category> <dc:creator>Mahid</dc:creator> <content:encoded><![CDATA[<div class="bbWrapper">Is the speed at which the paper helicopter falls due to its increased weight because gravity is stronger, or is it because air resistance is unable to keep it in the air because the weight is stronger than air resistance?</div>]]></content:encoded> <slash:comments>20</slash:comments> </item> <item> <title>When are reactive forces enough to support this body?</title> <pubDate>Sat, 15 Feb 2025 23:25:20 +0000</pubDate> <link>https://www.physicsforums.com/threads/when-are-reactive-forces-enough-to-support-this-body.1078420/</link> <guid isPermaLink="false">1078420</guid> <author>invalid@example.com (per persson)</author> <category domain="https://www.physicsforums.com/forums/introductory-physics-homework-help.153/"><![CDATA[Introductory Physics Homework Help]]></category> <dc:creator>per persson</dc:creator> <content:encoded><![CDATA[<div class="bbWrapper">In the book engineering mechanics statics and dynamics Hibbeler says:&quot; It should be noted that the single bearing supports in items (5) and (7), the single pin (8), and the single hinge (9) are shown to resist both force and couple-moment components. If, however, these supports are used in...<br /> <br /> <a href="https://www.physicsforums.com/threads/when-are-reactive-forces-enough-to-support-this-body.1078420/" class="link link--internal">Read more</a></div>]]></content:encoded> <slash:comments>14</slash:comments> </item> <item> <title>Synchronizing clocks at different locations to measure speed of light</title> <pubDate>Sat, 15 Feb 2025 22:06:42 +0000</pubDate> <link>https://www.physicsforums.com/threads/synchronizing-clocks-at-different-locations-to-measure-speed-of-light.1078573/</link> <guid isPermaLink="false">1078573</guid> <author>invalid@example.com (ESponge2000)</author> <category domain="https://www.physicsforums.com/forums/special-and-general-relativity.70/"><![CDATA[Special and General Relativity]]></category> <dc:creator>ESponge2000</dc:creator> <content:encoded><![CDATA[<div class="bbWrapper">When I tap my left hand and my right hand against the floor 3 feet apart, at the same time, I know that I’m not “really stretching 3 feet” at the same time, my brain is reading the nerves of each hand at a speed actually even slower than c but no matter how my circuits were designed it would...<br /> <br /> <a href="https://www.physicsforums.com/threads/synchronizing-clocks-at-different-locations-to-measure-speed-of-light.1078573/" class="link link--internal">Read more</a></div>]]></content:encoded> <slash:comments>21</slash:comments> </item> <item> <title>Can A Vector Have Components Of Say Y or Z in the X-Hat Direction?</title> <pubDate>Sat, 15 Feb 2025 21:54:14 +0000</pubDate> <link>https://www.physicsforums.com/threads/can-a-vector-have-components-of-say-y-or-z-in-the-x-hat-direction.1078553/</link> <guid isPermaLink="false">1078553</guid> <author>invalid@example.com (Ascendant0)</author> <category domain="https://www.physicsforums.com/forums/introductory-physics-homework-help.153/"><![CDATA[Introductory Physics Homework Help]]></category> <dc:creator>Ascendant0</dc:creator> <content:encoded><![CDATA[<div class="bbWrapper">While I only have a minute to touch on this right now, when I solved this, according to my instructor, I did everything right except at the very end, I didn&#039;t drop the partial vectors for each direction. The reason I didn&#039;t do so is because up to this point, my understanding was that a vector...<br /> <br /> <a href="https://www.physicsforums.com/threads/can-a-vector-have-components-of-say-y-or-z-in-the-x-hat-direction.1078553/" class="link link--internal">Read more</a></div>]]></content:encoded> <slash:comments>8</slash:comments> </item> <item> <title>Lasting effects of Mass and Distance Dilation</title> <pubDate>Sat, 15 Feb 2025 20:20:24 +0000</pubDate> <link>https://www.physicsforums.com/threads/lasting-effects-of-mass-and-distance-dilation.1078480/</link> <guid isPermaLink="false">1078480</guid> <author>invalid@example.com (Jkreider48)</author> <category domain="https://www.physicsforums.com/forums/special-and-general-relativity.70/"><![CDATA[Special and General Relativity]]></category> <dc:creator>Jkreider48</dc:creator> <content:encoded><![CDATA[<div class="bbWrapper">We know that time dilation is &quot;real&quot; in the sense that a subject at relativistic speeds or gravitational changes are measurable even when the subject returns to an &quot;at rest&quot; state. But are there lasting effects with mass and distance dilation under the same circumstances?</div>]]></content:encoded> <slash:comments>42</slash:comments> </item> <item> <title>How can I finish my wood shelf project to match my decor?</title> <pubDate>Sat, 15 Feb 2025 20:04:33 +0000</pubDate> <link>https://www.physicsforums.com/threads/how-can-i-finish-my-wood-shelf-project-to-match-my-decor.1078383/</link> <guid isPermaLink="false">1078383</guid> <author>invalid@example.com (DaveC426913)</author> <category domain="https://www.physicsforums.com/forums/diy-projects.264/"><![CDATA[DIY Projects]]></category> <dc:creator>DaveC426913</dc:creator> <content:encoded><![CDATA[<div class="bbWrapper">Just made a little shelf for the bathroom. It&#039;s made of finish-grade plywood. If I just spray it, it will look like spray-painted wood. (I&#039;d usually just use Tremclad gloss white). Can I put some sort of sealant coat on it so the spray coat is smooth? Do I put a top coat of shiny on it...<br /> <br /> <a href="https://www.physicsforums.com/threads/how-can-i-finish-my-wood-shelf-project-to-match-my-decor.1078383/" class="link link--internal">Read more</a></div>]]></content:encoded> <slash:comments>28</slash:comments> </item> <item> <title>Why Does Snow Pack Better Near the Melting Point?</title> <pubDate>Sat, 15 Feb 2025 16:34:38 +0000</pubDate> <link>https://www.physicsforums.com/threads/why-does-snow-pack-better-near-the-melting-point.939121/</link> <guid isPermaLink="false">939121</guid> <author>invalid@example.com (Charles Link)</author> <category domain="https://www.physicsforums.com/forums/general-discussion.14/"><![CDATA[General Discussion]]></category> <dc:creator>Charles Link</dc:creator> <content:encoded><![CDATA[<div class="bbWrapper">Over the last 20 years or more, I have made the observation that the snow for making a snowman only packs properly when the temperature is, in general, above freezing. This could be explained by the unique property of water, which, because it expands upon freezing, the solid phase will...<br /> <br /> <a href="https://www.physicsforums.com/threads/why-does-snow-pack-better-near-the-melting-point.939121/" class="link link--internal">Read more</a></div>]]></content:encoded> <slash:comments>141</slash:comments> </item> <item> <title>My Physics Life</title> <pubDate>Sat, 15 Feb 2025 16:19:55 +0000</pubDate> <link>https://www.physicsforums.com/threads/my-physics-life.1078470/</link> <guid isPermaLink="false">1078470</guid> <author>invalid@example.com (Gy3f)</author> <category domain="https://www.physicsforums.com/forums/new-member-introductions.240/"><![CDATA[New Member Introductions]]></category> <dc:creator>Gy3f</dc:creator> <content:encoded><![CDATA[<div class="bbWrapper">I am always thrilled about physics, and science in general. It shows me details of everything. I want to know how things work. I have been reading physics my materials for great knowledge. Then I also try to discover some.</div>]]></content:encoded> <slash:comments>3</slash:comments> </item> <item> <title>Angular momentum- rotating rod</title> <pubDate>Sat, 15 Feb 2025 15:57:42 +0000</pubDate> <link>https://www.physicsforums.com/threads/angular-momentum-rotating-rod.1078579/</link> <guid isPermaLink="false">1078579</guid> <author>invalid@example.com (palaphys)</author> <category domain="https://www.physicsforums.com/forums/introductory-physics-homework-help.153/"><![CDATA[Introductory Physics Homework Help]]></category> <dc:creator>palaphys</dc:creator> <content:encoded><![CDATA[<div class="bbWrapper">So my first approach was to use L=Iw.<br /> Computing I, moment of inertia,I=$$I_{center} = \frac{md^2}{4}$$<br /> $$L_{center} = I_{center} \omega = \frac{md^2\omega}{4}$$<br /> And hence I obtain an answer.<br /> However, when I further thought about the question, I realised that L is a vector and I can probably do...<br /> <br /> <a href="https://www.physicsforums.com/threads/angular-momentum-rotating-rod.1078579/" class="link link--internal">Read more</a></div>]]></content:encoded> <slash:comments>14</slash:comments> </item> <item> <title>Who is your favorite Jazz musician and what is your favorite song?</title> <pubDate>Sat, 15 Feb 2025 15:26:53 +0000</pubDate> <link>https://www.physicsforums.com/threads/who-is-your-favorite-jazz-musician-and-what-is-your-favorite-song.1051251/</link> <guid isPermaLink="false">1051251</guid> <author>invalid@example.com (BadgerBadger92)</author> <category domain="https://www.physicsforums.com/forums/art-music-history-and-linguistics.20/"><![CDATA[Art, Music, History, and Linguistics]]></category> <dc:creator>BadgerBadger92</dc:creator> <content:encoded><![CDATA[<div class="bbWrapper">I have always liked Jazz music (and blues, electric blues to be particular)<br /> <br /> Who is your favorite musician and song?<br /> <br /> I’ve always liked Herbie Hancock, especially his song “Maiden Voyage.”<br /> <br /> <span data-s9e-mediaembed="youtube"><span><iframe allowfullscreen="" scrolling="no" allow="autoplay" style="background:linear-gradient(0deg,rgba(0,0,0,0) 0,rgba(0,0,0,0) 72%,rgba(0,0,0,.04) 79%,rgba(0,0,0,.1) 83%,rgba(0,0,0,.25) 88%,rgba(0,0,0,.67) 100%),url(https://i.ytimg.com/vi/hwmRQ0PBtXU/hqdefault.jpg) 50% 50% / cover" src="https://www.youtube.com/embed/hwmRQ0PBtXU" data-s9e-mediaembed-c2l="youtube" data-s9e-mediaembed-c2l-oembed-id="hwmRQ0PBtXU" data-s9e-mediaembed-c2l-src="https://www.youtube.com/embed/hwmRQ0PBtXU?autoplay=1"></iframe></span></span></div>]]></content:encoded> <slash:comments>302</slash:comments> </item> <item> <title>Some questions about Coleman's Baby Universe model</title> <pubDate>Sat, 15 Feb 2025 14:09:31 +0000</pubDate> <link>https://www.physicsforums.com/threads/some-questions-about-colemans-baby-universe-model.1078582/</link> <guid isPermaLink="false">1078582</guid> <author>invalid@example.com (Suekdccia)</author> <category domain="https://www.physicsforums.com/forums/beyond-the-standard-models.66/"><![CDATA[Beyond the Standard Models]]></category> <dc:creator>Suekdccia</dc:creator> <content:encoded><![CDATA[<div class="bbWrapper">I know that this is speculative and that discussing theoretical models with no evidence supporting them is probably pointless, but I&#039;d like to ask a question about Coleman&#039;s baby universe model to understand it better and clarify some questions I have about it:<br /> <br /> In this article...<br /> <br /> <a href="https://www.physicsforums.com/threads/some-questions-about-colemans-baby-universe-model.1078582/" class="link link--internal">Read more</a></div>]]></content:encoded> <slash:comments>0</slash:comments> </item> <item> <title>Assistance Needed with OpenMC to Calculate Air Kerma and Mean Glandular Dose for Breast Voxel Phantom</title> <pubDate>Sat, 15 Feb 2025 13:27:59 +0000</pubDate> <link>https://www.physicsforums.com/threads/assistance-needed-with-openmc-to-calculate-air-kerma-and-mean-glandular-dose-for-breast-voxel-phantom.1078524/</link> <guid isPermaLink="false">1078524</guid> <author>invalid@example.com (REMS R)</author> <category domain="https://www.physicsforums.com/forums/nuclear-engineering.106/"><![CDATA[Nuclear Engineering]]></category> <dc:creator>REMS R</dc:creator> <content:encoded><![CDATA[<div class="bbWrapper">Hello everyone<br /> <br /> I am a radiation protection student and need assistance with OpenMC. I have a breast voxel phantom and I want to calculate the air kerma to determine the mean glandular dose. I&#039;m not sure what steps to follow to achieve this. Could someone guide me through the process?</div>]]></content:encoded> <slash:comments>1</slash:comments> </item> <item> <title>Circle approximation of a wave pulse on a string or spring</title> <pubDate>Sat, 15 Feb 2025 12:33:25 +0000</pubDate> <link>https://www.physicsforums.com/threads/circle-approximation-of-a-wave-pulse-on-a-string-or-spring.1078570/</link> <guid isPermaLink="false">1078570</guid> <author>invalid@example.com (Brian_D)</author> <category domain="https://www.physicsforums.com/forums/introductory-physics-homework-help.153/"><![CDATA[Introductory Physics Homework Help]]></category> <dc:creator>Brian_D</dc:creator> <content:encoded><![CDATA[<div class="bbWrapper">I tried using LaTeX and Preview, but when I click Preview I didn&#039;t see the preview. The tool bar turns red, but the LaTeX code does not appear as typeset text. The relevant equations are (1) V= sqrt(F/mu) where V is the wave speed, F is the tension force, and mu is the mass per unit length of...<br /> <br /> <a href="https://www.physicsforums.com/threads/circle-approximation-of-a-wave-pulse-on-a-string-or-spring.1078570/" class="link link--internal">Read more</a></div>]]></content:encoded> <slash:comments>11</slash:comments> </item> <item> <title>Talent Worthy of Wider Recognition</title> <pubDate>Sat, 15 Feb 2025 04:22:02 +0000</pubDate> <link>https://www.physicsforums.com/threads/talent-worthy-of-wider-recognition.1064653/</link> <guid isPermaLink="false">1064653</guid> <author>invalid@example.com (Hornbein)</author> <category domain="https://www.physicsforums.com/forums/art-music-history-and-linguistics.20/"><![CDATA[Art, Music, History, and Linguistics]]></category> <dc:creator>Hornbein</dc:creator> <content:encoded><![CDATA[<div class="bbWrapper">The double lead guitar technique was invented by George Harrison on Your Bird Can Sing but the style didn&#039;t catch on. Jimmy Page put it on the map in Ramble On, then the Allman Brothers made it their signature. I like double lead guitar because that unique soaring sound is something no other...<br /> <br /> <a href="https://www.physicsforums.com/threads/talent-worthy-of-wider-recognition.1064653/" class="link link--internal">Read more</a></div>]]></content:encoded> <slash:comments>48</slash:comments> </item> <item> <title>How to stop/reduce ultrasonic sound wave device?</title> <pubDate>Sat, 15 Feb 2025 03:25:45 +0000</pubDate> <link>https://www.physicsforums.com/threads/how-to-stop-reduce-ultrasonic-sound-wave-device.1063567/</link> <guid isPermaLink="false">1063567</guid> <author>invalid@example.com (bluetuliphead)</author> <category domain="https://www.physicsforums.com/forums/general-engineering.113/"><![CDATA[General Engineering]]></category> <dc:creator>bluetuliphead</dc:creator> <content:encoded><![CDATA[<div class="bbWrapper">I have a random but pressing question. <br /> I am currently being blasted a nearby ultrasonic noise machine which I can only get within 2 metres of and there is no one to appeal to regarding the issue.<br /> How can I disable/reduce the noise given the constraints? <br /> This is the device...<br /> <br /> <a href="https://www.physicsforums.com/threads/how-to-stop-reduce-ultrasonic-sound-wave-device.1063567/" class="link link--internal">Read more</a></div>]]></content:encoded> <slash:comments>38</slash:comments> </item> <item> <title>Is Fluorescence Possible in Twilight?</title> <pubDate>Sat, 15 Feb 2025 02:03:09 +0000</pubDate> <link>https://www.physicsforums.com/threads/is-fluorescence-possible-in-twilight.1053454/</link> <guid isPermaLink="false">1053454</guid> <author>invalid@example.com (FeatherGlow)</author> <category domain="https://www.physicsforums.com/forums/classical-physics.61/"><![CDATA[Classical Physics]]></category> <dc:creator>FeatherGlow</dc:creator> <content:encoded><![CDATA[<div class="bbWrapper">Earlier this year I saw what appeared to be a large glowing bird at twilight. The normal explanation for this is bioluminescent fungus contaminating a bird.<br /> <br /> I’m wondering if the effect might actually be a blue light effect where a fluorescent bird only appeared to glow because of the lighting...<br /> <br /> <a href="https://www.physicsforums.com/threads/is-fluorescence-possible-in-twilight.1053454/" class="link link--internal">Read more</a></div>]]></content:encoded> <slash:comments>25</slash:comments> </item> <item> <title>Chernobyl New Safe Confinement structure struck by drone… what now?</title> <pubDate>Sat, 15 Feb 2025 01:34:14 +0000</pubDate> <link>https://www.physicsforums.com/threads/chernobyl-new-safe-confinement-structure-struck-by-drone-what-now.1078577/</link> <guid isPermaLink="false">1078577</guid> <author>invalid@example.com (Flyboy)</author> <category domain="https://www.physicsforums.com/forums/nuclear-engineering.106/"><![CDATA[Nuclear Engineering]]></category> <dc:creator>Flyboy</dc:creator> <content:encoded><![CDATA[<div class="bbWrapper">Last night, a suspected Russian one-way drone with an explosive warhead impacted the New Safe Confinement shelter over the ruins of Chernobyl’s #4 reactor.<br /> <br /> <img src="https://www.physicsforums.com/attachments/img_3991-jpeg.357330/" class="bbImage " style="" alt="IMG_3991.jpeg" title="IMG_3991.jpeg" width="465" height="620" loading="lazy" /><br /> The explosion caused damage to at least the outer shell, with an unclear amount of damage to the interior of the facility...<br /> <br /> <a href="https://www.physicsforums.com/threads/chernobyl-new-safe-confinement-structure-struck-by-drone-what-now.1078577/" class="link link--internal">Read more</a></div>]]></content:encoded> <slash:comments>1</slash:comments> </item> <item> <title>Antimatter-matter annihilation: significance of opposite charge</title> <pubDate>Fri, 14 Feb 2025 23:33:36 +0000</pubDate> <link>https://www.physicsforums.com/threads/antimatter-matter-annihilation-significance-of-opposite-charge.1078342/</link> <guid isPermaLink="false">1078342</guid> <author>invalid@example.com (NothingsMatter)</author> <category domain="https://www.physicsforums.com/forums/high-energy-nuclear-particle-physics.65/"><![CDATA[High Energy, Nuclear, Particle Physics]]></category> <dc:creator>NothingsMatter</dc:creator> <content:encoded><![CDATA[<div class="bbWrapper">I did a forum search and couldn&#039;t find this, so forgive me if my search skills were insufficient to find a previous explanation of this.<br /> <br /> But, I&#039;m a bit confused as to why merely having the same mass but opposite charge would cause, for example, an electron and positron to annihilate each other...<br /> <br /> <a href="https://www.physicsforums.com/threads/antimatter-matter-annihilation-significance-of-opposite-charge.1078342/" class="link link--internal">Read more</a></div>]]></content:encoded> <slash:comments>18</slash:comments> </item> <item> <title>A new planet?</title> <pubDate>Fri, 14 Feb 2025 19:08:09 +0000</pubDate> <link>https://www.physicsforums.com/threads/a-new-planet.1078572/</link> <guid isPermaLink="false">1078572</guid> <author>invalid@example.com (mad mathematician)</author> <category domain="https://www.physicsforums.com/forums/astronomy-and-astrophysics.71/"><![CDATA[Astronomy and Astrophysics]]></category> <dc:creator>mad mathematician</dc:creator> <content:encoded><![CDATA[<div class="bbWrapper">I must confess after another exam I took at Thursday, I look at the sky at night and there was a bright light. Well I thought to myself it must be venus or jupiter.<br /> <br /> But maybe it&#039;s this new planet after Neptune:<br /> <a href="https://eladelantado.com/news/new-planet-behind-neptune-official/" target="_blank" class="link link--external" rel="nofollow ugc noopener">https://eladelantado.com/news/new-planet-behind-neptune-official/</a><br /> <br /> Ah, and...<br /> <br /> <a href="https://www.physicsforums.com/threads/a-new-planet.1078572/" class="link link--internal">Read more</a></div>]]></content:encoded> <slash:comments>1</slash:comments> </item> <item> <title>Technical Discussion on TMESH Tally in MCNP 6.2 and 6.3</title> <pubDate>Fri, 14 Feb 2025 18:45:19 +0000</pubDate> <link>https://www.physicsforums.com/threads/technical-discussion-on-tmesh-tally-in-mcnp-6-2-and-6-3.1078514/</link> <guid isPermaLink="false">1078514</guid> <author>invalid@example.com (alinegranja)</author> <category domain="https://www.physicsforums.com/forums/nuclear-engineering.106/"><![CDATA[Nuclear Engineering]]></category> <dc:creator>alinegranja</dc:creator> <content:encoded><![CDATA[<div class="bbWrapper">Hello everyone,<br /> <br /> I would like to start a technical discussion about the TMESH tally in MCNP versions 6.2 and 6.3. From my studies, TMESH is similar to +F6, tied to a mesh, and its results are given in terms of MeV/cm³. I wanted to know if there is any way (a multiplier or conversion factor) to...<br /> <br /> <a href="https://www.physicsforums.com/threads/technical-discussion-on-tmesh-tally-in-mcnp-6-2-and-6-3.1078514/" class="link link--internal">Read more</a></div>]]></content:encoded> <slash:comments>2</slash:comments> </item> <item> <title>US Government Shuts Down NIH Grant Reviews and More</title> <pubDate>Fri, 14 Feb 2025 18:33:09 +0000</pubDate> <link>https://www.physicsforums.com/threads/us-government-shuts-down-nih-grant-reviews-and-more.1078192/</link> <guid isPermaLink="false">1078192</guid> <author>invalid@example.com (gleem)</author> <category domain="https://www.physicsforums.com/forums/biology-and-medical.82/"><![CDATA[Biology and Medical]]></category> <dc:creator>gleem</dc:creator> <content:encoded><![CDATA[<div class="bbWrapper"><a href="https://www.nature.com/articles/d41586-025-00231-y" target="_blank" class="link link--external" rel="nofollow ugc noopener">https://www.nature.com/articles/d41586-025-00231-y</a><br /> <br /> <blockquote data-attributes="" data-quote="" data-source="" class="bbCodeBlock bbCodeBlock--expandable bbCodeBlock--quote js-expandWatch"> <div class="bbCodeBlock-content"> <div class="bbCodeBlock-expandContent js-expandContent "> &quot;His administration has abruptly canceled research-grant reviews, travel and training for scientists inside and outside the National Institutes of Health (NIH), the world’s largest public biomedical funder. . . . The cancelling of... </div> </div> </blockquote><br /> <a href="https://www.physicsforums.com/threads/us-government-shuts-down-nih-grant-reviews-and-more.1078192/" class="link link--internal">Read more</a></div>]]></content:encoded> <slash:comments>36</slash:comments> </item> <item> <title>Coulomb's law taken to the extreme</title> <pubDate>Fri, 14 Feb 2025 18:32:17 +0000</pubDate> <link>https://www.physicsforums.com/threads/coulombs-law-taken-to-the-extreme.1078447/</link> <guid isPermaLink="false">1078447</guid> <author>invalid@example.com (neobaud)</author> <category domain="https://www.physicsforums.com/forums/electromagnetism.302/"><![CDATA[Electromagnetism]]></category> <dc:creator>neobaud</dc:creator> <content:encoded><![CDATA[<div class="bbWrapper">So Coulomb&#039;s law is this simple formula for calculating the force between two charges. <br /> Kq1*q2/(r^2)<br /> <br /> (Disclaimer: I know this computation is not actually possible I was just wondering if it would give the correct result)<br /> <br /> I was wondering if it is valid to sum the force vector from every charge...<br /> <br /> <a href="https://www.physicsforums.com/threads/coulombs-law-taken-to-the-extreme.1078447/" class="link link--internal">Read more</a></div>]]></content:encoded> <slash:comments>36</slash:comments> </item> <item> <title>Particle in Infinite Square Well</title> <pubDate>Fri, 14 Feb 2025 17:47:45 +0000</pubDate> <link>https://www.physicsforums.com/threads/particle-in-infinite-square-well.1067468/</link> <guid isPermaLink="false">1067468</guid> <author>invalid@example.com (AgingStudent49)</author> <category domain="https://www.physicsforums.com/forums/quantum-physics.62/"><![CDATA[Quantum Physics]]></category> <dc:creator>AgingStudent49</dc:creator> <content:encoded><![CDATA[<div class="bbWrapper">In thinking about the particle in an infinite square well, it the commonly espoused boundary conditions of ψ(0) = 0 and ψ(L) = 0 seem somewhat arbitrary. What in nature forces the wave function to vanish at the boundaries? If the particle can&#039;t escape and there is no energy loss, why not...<br /> <br /> <a href="https://www.physicsforums.com/threads/particle-in-infinite-square-well.1067468/" class="link link--internal">Read more</a></div>]]></content:encoded> <slash:comments>2</slash:comments> </item> <item> <title>Can you calculate the probability of a complex logic expression?</title> <pubDate>Fri, 14 Feb 2025 15:53:56 +0000</pubDate> <link>https://www.physicsforums.com/threads/can-you-calculate-the-probability-of-a-complex-logic-expression.1078503/</link> <guid isPermaLink="false">1078503</guid> <author>invalid@example.com (yeet991only)</author> <category domain="https://www.physicsforums.com/forums/set-theory-logic-probability-statistics.78/"><![CDATA[Set Theory, Logic, Probability, Statistics]]></category> <dc:creator>yeet991only</dc:creator> <content:encoded><![CDATA[<div class="bbWrapper">Suppose this expression : ((A ∨ ~B) ∨ (C -&gt; D)) <br /> This simplifies to : A + ~B + ~C + D , using boolean algebra.<br /> Now suppose i know that this expression is true: p( ((A ∨ ~B) ∨ (C -&gt; D)) ) = 1;<br /> and I also know that p(A) = 0.3 , p(B) = 0.99 , p(C) = 0.92 .<br /> but the probability of the expression is...<br /> <br /> <a href="https://www.physicsforums.com/threads/can-you-calculate-the-probability-of-a-complex-logic-expression.1078503/" class="link link--internal">Read more</a></div>]]></content:encoded> <slash:comments>2</slash:comments> </item> </channel> </rss>