Link Definition and 228 Threads

ATTENTION: @Greg Bernhardt Viewing post https://www.physicsforums.com/posts/7086547 I clicked on the link "USA" just below the image -- https://www.physicsforums.com/javascript%3AsetPOESUS() and got this message: Sorry, you have been blocked You are unable to access physicsforums.com...

It's just a link, Unreal? [Mentor note: The thread title has been edited to be a bit more specific]

"Heat is the transfer of kinetic energy between molecules. If the velocity is more, the kinetic energy will be more so that the heat is more." "As an object's speed increases, the drag force from the fluid increases exponentially. For example, when you drive at high speeds, the frictional force...

Car has drag coeffecient of 0.35 and drink 5L/100km, if car Cd is reduced to 0.20 and everthying else stay the same(frontal area,power,weight etc),how much will car drink? Is it possible to calcualte this or we need something more? I am interested if exist direct link/formula between Cd and...

I found this quote online: “Multiplication is the mathematical manifestation of the fundamental physical phenomenon of proportionality (as addition is to combination).” Question 1: How are multiplication and proportion linked? How can and WHY DOES multiplication model proportion? (My...

https://www.1news.co.nz/2022/07/22/no-clear-link-between-low-serotonin-and-depression-study/ https://www.nature.com/articles/s41380-022-01661-0

Hello, I am reading a course on signal processing involving the Z-transform, and I just read something that leaves me confused. Let ##F(z)## be the given Z-transform of a numerical function ##f[n]## (discrete amplitudes, discrete variable), which has a positive semi-finite support and finite...

While researching S protein interactions I stumbled across a couple of recent papers studying the increased risk of developing Parkinson's after a Covid infection and the possible mechanism that plays a role there. https://pubmed.ncbi.nlm.nih.gov/34860005/ here is the full version of the study...

Last link points to https://docs.mathjax.org/en/latest/tex.html#supported-latex-commands which is no more I think it's https://docs.mathjax.org/en/latest/input/tex/macros/index.html nowHowever, there is far too much in there that doesn't work in the PF version, so maybe there is another link...

Summary:: Can someone point me to an example solution? Hello The attached figure is a four bar link. Each of the four bars has geometry, mass, moment of inertia, etc. A torque motor drives the first link. I am looking for an example (a simple solution so I can ground my self before...

Hi, I am interested in the topic of hand calculations of chain link's strength. I am talking about a regular industrial chain with hanging weight. From what I've read, there are 3 potentially possible approaches: - Lame's problem (circular cross-section has to be replaced with equivalent...

This thread I thought deserved a bump. Just read Greg's initial post. Here's the Amazon link, PF gets a kickback if you use this link from your purchase on Amazon, see Greg's linked post for details.

I've heard that there is some link between these two values (they're so close!) but I can't seem to find it anywhere. Can someone point me in the right direction? (there's also the J-invariant 196884, well you get the idea)

Hi! I need a keyboard shortcut to "Email a link to this page" in Firefox 88.0 running on both Win10Pro & Mojave 10.14.6. Anyone got a way to configure this? Or know of a way to do this? Thanks!

https://phys.org/news/2021-04-billion-year-old-fossil-reveals-link-evolution.html I used to have some literature on ancient single cell organisms, but I haven't seen it in decades. https://www.cell.com/current-biology/fulltext/S0960-9822(21)00424-3 Sediments of the Torridonian sequence of...

Hi, I was just attempting this problem and was confused about the calculation process involved. Context: In earlier parts of the question, we calculate the gain ## G ## and effective aperture ## A ## for the parabolic antennae. My Attempt: We are given the power at the output ## x ## in Watts...

If I understand correctly (a big caveat), one shows that if one can get from one function to the other via a Fourier transform and multiplication by a constant, then the width of the corresponding Gaussian wave of one gets larger as that of the other gets smaller, and vice-versa, and by a bit...

I had many attempts on trying to solve this one, but I got always stuck in the problem-solving part: how do I manage to find the source-speed from the Doppler formula, in an analytical way, and then reach to the result-formula? Anyway, I'm pretty sure the only formula needed to solve this...

This post is just a test. Some usernames of members are made of two or more "words" separated with one or more spaces. The symbol @ has been used as a link to profile page for the named member, but not clear if the spaces interfere with this link expressiveness. @membername1234 @membername...

I've seen some broken external links in physics forums Which have been changed to BROKEN as moderators. Is replacing the broken links with archived links(Ex. archive.org) a bad idea?

When the exposed conductive parts (door, protective screen, closing panel, etc.) do not have any devices or equipment fixed on them, the equipotential connection of these exposed conductive parts must be provided using a conductor, minimum cross-section 2.5 mm² as it's stated in IEC (see...

Hello, I've got this question: A 16 MB file is compressed using a compression ratio of 4. The resulting compressed file is transmitted over a wireless connection that offers a maximum data rate of 1.2 Gbps. If a throughput of 60% can be achieved, and assuming there are no other transmissions...

Every time I want to point a newbie to the latex tutorial I have to hunt it down myself. It would be really nice if there was a link or an icon right on the reply window to use in the post. Or am I missing something?

Dear Forum Members, I need to create and use dynamic-link library (DLL) for Fortran application using Compaq Visual Fortran 6.6. The following code works just fine: ########################################### PROGRAM AMAIN1 IMPLICIT NONE REAL(8):: A,B,S A = 1D0 B = 2D0 CALL SUBRO1(A,B,S)...

https://courses.lumenlearning.com/boundless-physics/chapter/basics-of-kinematics/

I recently found this article about the dynamics of the wave function. It has some good simple illustrations and I found it valuable. But the author has a question himself, about understanding the Schrodinger equation. I wonder if anybody here could fill in the missing piece. The relevant part...

Homework Statement Choose a technology such as MP3 players, lasers, medical imaging, or another that interests you. Research the internet and find out how it is related to the physics of light and waves. In approximately 100 to 150 words, write a paragraph explaining the link between our...

Hi, I'm trying to form an expression for a rectifier supplying a DC link with current, without actually rectifying a 3-phase input. Usage of the model is really only concerned with the RMS values and the active power drawn from the AC supply. The DC link is just a capacitor so that: dVDC/dt =...

So I created a MS SQL db , but now I cannot link to it. I WOULD like to create a database in my C:/Cfusion/wwroot folder and not in ProgramFiles/MicsoSQL/Data folder. Is that possible? How? I cannot create a new database in anywhere but ProgramFiles/MicsoSQL/Data folder. Now I have an mdf in...

Hey guys, I know this is a bad question but I would love to know how. Usually, in the examples, the loads are given as UDL where you can to find same reaction at both ends of beam. What if the beam loadings are with multiple point loads, (5 or 6 point load) and the reaction of the beam at both...

Submitted by @Charles Link Solved by: @MAGNIBORO and @maline RULES: 1) In order for a solution to count, a full derivation or proof must be given. Answers with no proof will be ignored. 2) It is fine to use nontrivial results without proof as long as you cite them and as long as it is "common...

Using : Ansys Workbench 16 Educational I want to build simple frame and simulate stress state and deformation when that frame is lifted. I have constructed my geometry in Design Modeler using line body's. My lifting cable has circular cross section with diameter of 10 mm. My frame has square...

Dear PF Forum, Can someone help me with this matter? I want to ask a question in PF concerning a particular video. You'll see that the video popped up in my thread. I use insert link above. But what I want to do is simply, insert the link, so the use can click the video to watch it without...

Unexpected interaction between dark matter and ordinary matter in mini-spiral galaxies "We studied 36 galaxies, which was a sufficient number for statistical study. By doing this, we found a link between the structure of ordinary, or luminous matter like stars, dust and gas, with dark matter."...

I am familiar with linking external libraries in IDE like Eclipse, Netbeans etc. But in my college they use use vim for programming on Linux. To learn more about vim editor I installed it on my home computer.I can compile basic C++ programs on it with one or two .cpp/.h files. I think it is...

Homework Statement $$ E = -\vec{v_{obs}} \cdot \vec{p} $$ Where ## \vec{p} ## is the four momentum, and ## \vec{v_{obs}}## the velocity of the observer. Homework EquationsThe Attempt at a Solution [/B] This was a stated result in a GR course. I look through my SR notes and find that I...

Is there a connection between consciousness and emotions? Imagine humans are a class 5 conscious animal and have the most complex emotions. An elephant or a gorilla may be a class 4 conscious animal, a dog a class 3 etc. I would certainly think a gorilla possesses a deeper consciousness than a...

Hi, I have a thread about 3D graphics in Programming/Computer science subforum: https://www.physicsforums.com/threads/setting-up-3-d-rotation-in-web-page.881634/#post-5550648 where I post a Dropbox link to an HTML5/Javascript file in post #16. When I run Physics Forum with the Edge browser...

I apologize in advance that this is not the usual format. I don't have a specific question, and it's not out of peer review just yet, but this new study seems pretty interesting overall. Does anyone here want to share any thoughts on this? Seems pretty darn interesting to me...

I'm given this problem to solve with the assumption as stated above. The answers need not be logical as long as the linkage mechanism can be simulated. I've attempted the question using Mercedes Mono Wiper mechanism but only manage to cover 41% given the width of the wiper. May I ask if there...

Is it true the vaccine and autism link is completely refuted and the original doctor who mentioned the link made it up? I avoided any flu shots because didn't want to get autism.. see the link: Edit: not valid source http://www.cdc.gov/vaccinesafety/concerns/autism.html

In the beginning the forum says, "Have a university web page? Consider linking to Physics Forums. Every little bit helps!" Well, I'm a student at a university. How do I do this?

Animals dream and have no word, so articulate language is not necessary to dream and may be to think. Since one preceded the other, may be there is a relation.

I am conducting some research into finding the force which a rotating link will exert. The link is actuated by a motor which provides 30Nm of torque. I need to find force in x,y,z directions F=[Fx,Fy,Fz]; Is the answer [Fx,Fy,Fz]=[tau/Px,tau/Py,tau/Pz]

Homework Statement Power=P, rotation speed n1, rotation speed n2, chain center distance c, life = Lh All I need for this one is the formula for sprocket diameter. I have found calculators (https://www.rbracing-rsr.com/calcsprocketdiam.html) but no reference to the formula. Chain pitch and...

how to use the Chebyshev optimality criterion to the second degree polynomial?

Homework Statement A student tries to raise a chain consisting of three identical links. Each link has a mass of 200 g. The three-piece chain is connected to light string and then suspended vertically, with the student holding the upper end of the string and pulling upward. Because of the...

Can you tie this together for me? My understanding: If something does not have mass, it does not interact with time. If something has mass it interacts with spacetime. When mass interacts with spacetime, and creates gravity, it may travel through n+1 dimensions. My questions: A.Time is...

Homework Statement [/B] Find the instantaneous centers of the linkage below. Homework Equations # of ICs = n(n-1) / 2 The Attempt at a Solution [/B] From the equation above, there are 4(4-1)/2 = 6 ICs in this linkage. But one thing I don't understand is how there are 4 links when 2 and 3...

Homework Statement Plot luminosity distance and redshift z Homework Equations $$d_L(z)=(1+z)r(z)$$ where d_L(z) is luminosity distance and r(z) is the comoving distance. and we have $$r(z)= \frac{H_0^{-1}}{\sqrt\Omega_K}*sinn[\sqrt{\Omega_K}\int_0^z\frac{dz'}{\sqrt{\Omega_M(1+z')^3}}]$$ where...