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Q&A

General Q&A about physics of any type and at any level

85 posts ·
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I have recently heard of Apsidal Vectors. I was searching about it through internet. I had found the video in YT. I had found similar question in PF. But, the PF answer wasn't clear to me. I am jus...

0 answers  ·  posted 1y ago by Anonymous‭

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Since, there's no book category currently so, I am asking it here. And, It can be moved to that category later. I want to start learning now so, I don't want to wait. Which book is best for Clas...

1 answer  ·  posted 1y ago by deleted user  ·  last activity 1y ago by deleted user

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$$F=F(q,p,t)$$ $$\frac{dF}{dt}=\frac{\partial F}{\partial q}\frac{\partial q}{\partial t}+\frac{\partial F}{\partial p}\frac{\partial p}{\partial t}+\frac{\partial F}{\partial t}$$ $$=\frac{\part... 0 answers · posted 1y ago by deleted user · edited 1y ago by deleted user 66% +2 −0 What is semiholonomic is? Holonomic actually means two point can be expressed by a equation. Non-holonomic can be expressed but, not properly. Holonomic e.g. r^2-a^2=0 Non-holonomic e.g. r^2-a... 1 answer · posted 1y ago by Anonymous‭ · last activity 1y ago by HDE 226868‭ 62% +3 −1 L=T-U Here, L is Lagrangian. T is kinetic energy. U is potential energy. But, what Lagrangian actually is? I know what Holonomic and non-holonomic is. But, I was thinking what the Lagrangian re... 2 answers · posted 1y ago by deleted user · last activity 1y ago by deleted user 60% +1 −0 In my notes from University the reason a material can exhibit superconducting properties is at really low temperatures electrons form Cooper pairs of which the electrons of the Cooper pairs have lo... 0 answers · posted 1y ago by MissMulan‭ 50% +0 −0 How to derive the Lagrangian differential force?$$\frac{d}{dt}(\frac{\partial L}{\partial \dot{x}})+\frac{\partial L}{\partial x}=0$$I was trying to do something.$$L=T-U=\frac{1}{2} m\dot{x}^...

1 answer  ·  posted 1y ago by deleted user  ·  last activity 1y ago by celtschk‭

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If planet 9 exists, is it correct to say that it is a "dark planet"? By "dark" here I mean to a planet that doesn't reflect enough light to easily be seen from normal telescopes (in the current co...

2 answers  ·  posted 2y ago by deleted user  ·  last activity 1y ago by HDE 226868‭

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We know that electrons always repel electrons. But, if somehow they collide, then what will happen? I found a related question of above one in Quora. An incoming electron can instead make them ...

0 answers  ·  posted 1y ago by deleted user

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What will happen if an electron and a proton collide? They attract each other inside an atom. But, why they don't collide inside atoms? Does the "boundary" of the nucleus push them away? depends...

2 answers  ·  posted 1y ago by deleted user  ·  edited 1y ago by deleted user

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This gravitational field we move inside has some distance L after which it becomes 0.Before L it is just like any gravitational field. Suppose we move inside that gravitational field.The accelerat...

1 answer  ·  posted 1y ago by MissMulan‭  ·  last activity 1y ago by Mithrandir24601‭

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Would a colony on earth's moon need to be deeply underground to ensure more natural gravity (by getting closer to its core)?

2 answers  ·  posted 1y ago by deleted user  ·  last activity 1y ago by Canina‭

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I was reading "Introduction to classical Mechanics" by David Morin. In that book they wrote that The third law says we will never find a particle accelerating unless there’s some other particle ...

3 answers  ·  posted 1y ago by deleted user  ·  last activity 1y ago by Olin Lathrop‭

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If we have a force which changes depending on the position of a particle, how can we find the position of the particle at some time $t$? We can find its velocity if it has travelled a given distan...

1 answer  ·  posted 1y ago by MissMulan‭  ·  last activity 1y ago by celtschk‭

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In signal processing, are signals modeled in only one way (digitally or analogously) or are there some signals which can be modeled in both ways?

3 answers  ·  posted 1y ago by deleted user  ·  last activity 1y ago by Lundin‭

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We have place a charged particle of 2C with mass 2kg, 1mm above a current-carrying wire of 1A.The charged particle has an initial velocity of 100m/s The magnetic field of the wire for simplicity w...

0 answers  ·  posted 1y ago by MissMulan‭  ·  edited 1y ago by MissMulan‭

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I have heard the physicist Laurence Krauss claiming that he believes that the universe is flat. Okay, but if we take four astronomers and we put one in the north pole, one in the south pole, one i...

2 answers  ·  posted 1y ago by deleted user  ·  last activity 1y ago by celtschk‭

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I stumbled these pictures on Quora, and I'm assuming they were real. Wouldn't the supporter (person whom gun is mounted on) suffer hearing loss? Wouldn't the barrel burn his ear? I'm assu...

1 answer  ·  posted 2y ago by TextKit‭  ·  closed 1y ago by Mithical‭

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Suppose we have an electric dipole of charge Q+ and Q-.The charges of the dipole are fixed (they cant move closer to each other than they already are).If we place a test particle at some distance r...

1 answer  ·  posted 1y ago by MissMulan‭  ·  last activity 1y ago by Olin Lathrop‭

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How can I turn this floor lamp into a reading light? I want all light exiting upwards from the lamp shade to point down. Do I just buy a mirror and put it on top of the lamp shade? Then the mirror...

0 answers  ·  posted 2y ago by TextKit‭  ·  edited 1y ago by TextKit‭

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I am having trouble understanding what a cosmic inflation is. Please try to suffice an explanation for non physicists / non formal students for physics / general audience. I understand that an ...

2 answers  ·  posted 2y ago by deleted user  ·  last activity 1y ago by deleted user

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Should Earth's moon colonies being deep underground ensure natural heating? By natural I mean "non artificial" i.e. not from "artificial" air conditioning. The question is based on the thought th...

1 answer  ·  posted 1y ago by deleted user  ·  last activity 1y ago by Dave Tweed‭

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Decibel level listed of solfege. Do Re Mi Fa So La Ti Do 24 27 30 32 36 40 45 80 I saw that whispering decibel level is around 40. And, normal voice level is ...

1 answer  ·  posted 1y ago by deleted user  ·  last activity 1y ago by Olin Lathrop‭

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In Srednicki's proof of the spin-statistics theorem for scalar fields ("Quantum Field Theory", section 4), he considers interaction terms, added to the free Hamiltonian, that are Hermitian function...

1 answer  ·  posted 2y ago by Ezekiel‭  ·  last activity 2y ago by Mithrandir24601‭

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Is this advice correct? Are they alluding to Freezing Point Depression? Adding salt to tap water lowers the Crystalloid's freezing point. Pour 3 tbsp (51 g) of salt into each of your 3 plast...

1 answer  ·  posted 2y ago by TextKit‭  ·  last activity 2y ago by manassehkatz‭

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Please see the images below. I owned these Mykita John glasses for three years, which feels short for glasses to break! Every day, I fold them them before placing it on my night stand and going to ...

1 answer  ·  posted 2y ago by TextKit‭  ·  last activity 2y ago by Olin Lathrop‭

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In 1970, the USSR began drilling at the Kola Super-deep Borehole. The target depth was 15,000 meters; The stated areas of study were the deep structure of the Baltic Shield, seismic discontinuit...

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I'm not asking about cleaning human organs here. This handheld power scrubber looks like your average rotary toothbrush! Indubitably I know that a toothbrush's brush head can be far gentler than...

0 answers  ·  posted 2y ago by TextKit‭  ·  closed 2y ago by Mithrandir24601‭

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Let's say we have a single plate with liquid on both sides rising up due to surface tension. The meniscus formed has a radius of curvature $R$. I'm trying to find the excess pressure, i.e, the pre...

0 answers  ·  posted 2y ago by TripleFault‭

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My optician counselled me I don't recommend a 1.74 index with a metal grooved frame, like the one you want from ic! Berlin, because the edge will be less resilient and be more susceptible to chi...

1 answer  ·  posted 2y ago by TextKit‭  ·  last activity 2y ago by Olin Lathrop‭

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I don't understand either of these Reddit comments that are still too complicated. Please simplify? Alfenhose An interesting phenomena, it is because the brain doesn't store what you saw during ...

0 answers  ·  posted 2y ago by TextKit‭  ·  closed 2y ago by Mithrandir24601‭

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The major advantage of Alternating Current is that it can be transmitted to large distances without significant losses, which is not possible in Direct Current. Had economical superconducting wire...

2 answers  ·  posted 2y ago by theabbie‭  ·  last activity 2y ago by celtschk‭

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I have a question about the discussion of constrained Lagrangian systems in the book Mathematical Aspects of Classical and Celestial Mechanics by Arnold et al. (section 1.2.5). The Lagrangian syst...

1 answer  ·  posted 2y ago by Ezekiel‭  ·  last activity 2y ago by Derek Elkins‭

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I asked this question on Stack Exchange, and didn't get an answer, but maybe someone here will be able to help. In non-relativistic quantum mechanics, the normalization condition for position eige...

1 answer  ·  posted 2y ago by Ezekiel‭  ·  last activity 2y ago by Derek Elkins‭

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In special relativity, spacetime coordinates are normally given as $$(ct, x, y, z) \tag{S}$$ with the metric being either $$g = \operatorname{diag}(-1,1,1,1) \tag{+}$$ or g = \operatorname{d...

1 answer  ·  posted 2y ago by celtschk‭  ·  last activity 2y ago by dmckee‭

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