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Q&A

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

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Presuppose that I need vinegar of $c$ concentration, where $c$ < any concentration listed below. Let $w$ be the price of water that I'll use to dilute. How do I deduce which concentration (of V...

1 answer  ·  posted 1mo ago by TextKit‭  ·  closed 16d ago by Mithrandir24601‭

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Starting from the classical osmosis experiment, a U-shaped tube with a semi-permeable membrane, I would like to consider the case when the solute added to one of the compartments (labelled A) is co...

0 answers  ·  posted 2mo ago by Joce‭

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Suppose we have a gravitational wave which obeys the equation: $[G_{tt}-c^{2}G_{xx}]h_{\mu\nu}=0$ Lets take the case where $h_{\mu\nu}\ne0$ so we are left with the classical wave equation.Suppose...

0 answers  ·  posted 4mo ago by Volpina‭

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Gravitational waves can be derived from the non-linear Einstein field equations and since they are by definition waves they must obey the wave equation: $u_{tt}=c^{2}u_{xx}$ but in General Rela...

1 answer  ·  posted 4mo ago by Volpina‭  ·  last activity 4mo ago by Mithrandir24601‭

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Lets say we have a mass connected to a spring.Assuming not any friction the ODE which describes the system is $m\frac{d^{2}x}{dt^{2}} = -kx$ We can set 2 Dirichlet boundary conditions $x(0)=0$ an...

1 answer  ·  posted 4mo ago by Volpina‭  ·  last activity 4mo ago by Technically Natural‭

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In the context of quantum field theory, why is it impossible for two photons (or other massless bosons like gluons) to collide and produce a single photon? This kind of a process is supposed to be ...

2 answers  ·  posted 4mo ago by Technically Natural‭  ·  last activity 4mo ago by Derek Elkins‭

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I'm trying to understand the uncertainty principle and its implications for particle measurement. From what I've read, it seems that the principle states that we cannot simultaneously know the exac...

0 answers  ·  posted 6mo ago by Reinstate Monica on Stack Exchange‭

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Question I was wondering what force make drop slow down? Does every time a drop push toothpick back into bottle? And of course how to solve it. Struct This is a bottle be pierced by a wooden too...

0 answers  ·  posted 7mo ago by Dead_Bush_Sanpai‭  ·  closed 4mo ago by ArtOfCode‭

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At home daily, I need to mix my table salt + COLD tap water. As "Marine salts dissolve faster and more thoroughly when added to circulating water," I "use a powerhead to speed up mixing time — my V...

2 answers  ·  posted 8mo ago by TextKit‭  ·  last activity 3mo ago by matthewsnyder‭

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Suppose a ferromagnetic material with initial magnetization $M_o$.Is there some specific formula which calculates the total magnetization $M$ as a function of $M_{o}$ and the Curie temperature $T_{... 1 answer · posted 10mo ago by MissMulan‭ · last activity 4mo ago by Anyon‭ 60% +1 −0 Suppose we have a arc of charges with some charge density$\lambda(\theta) = sin\theta$.I am using polar coordinates for convenience.But how can I find the direction of the unit vector of the net e... 0 answers · posted 10mo ago by MissMulan‭ · edited 10mo ago by samcarter‭ 25% +0 −4 I need to separate these two parts, the opposite of the GIF below. While my hunky husband was lifting the chair up, and my brawny brother pushing the frame down, I kept hitting the top of the slid... 0 answers · posted 11mo ago by Este‭ · closed 11mo ago by Monica Cellio‭ 60% +1 −0 The general formula for a EM wave (solving for the E field) is: where$\varepsilon = \varepsilon _{r}+j\frac{\sigma }{\omega }My professor told me that the conductivity of vacuum is 0 so we... 0 answers · posted 12mo ago by MissMulan‭ 28% +0 −3 Say we have a four underwater components tidal power / hydro power system. Component A. A propeller would always orient along the same direction regardless the direction of the flow. This is th... 0 answers · posted 1y ago by HolyDamn2.0‭ · edited 1y ago by HolyDamn2.0‭ 28% +0 −3 Part 1 Say we have a round water pool, the radius is 10m, and the water depth is 2m. C is a fixed point: Fixed on the surface of water. Fixed at the center of the pool. F1 is stable forc... 2 answers · posted 1y ago by HolyDamn2.0‭ · last activity 12mo ago by Mithical‭ 71% +3 −0 The title is a framing for a theoretical question; I'm not asking for practical advice. A friend was recently in this situation and my attempts to apply what I remember of a couple semesters of co... 1 answer · posted 1y ago by Monica Cellio‭ · last activity 1y ago by Olin Lathrop‭ 71% +3 −0 When a pendulum made of a conducting material moves through a magnetic field, it's a well-established fact that it experiences a retarding force, thus slowing it down, however, I'm unable to unders... 1 answer · posted 1y ago by esrdtfghjk‭ · last activity 1y ago by Olin Lathrop‭ 50% +0 −0 Maxwell's first law in differential form states that $$\triangledown \cdot E = \frac{\rho}{\epsilon_{o}}$$ . In case of 1d can we say that $$\rho = \lambda$$ where $$\lambda$$ is the linear char... 1 answer · posted 1y ago by MissMulan‭ · last activity 12mo ago by celtschk‭ 60% +1 −0 Suppose we perform the double slit experiment , but we fire instead 2 electrons instead of 1. In the double slit experiment performed in the 1920s a interference pattern was observed at the screen... 0 answers · posted 1y ago by MissMulan‭ 57% +2 −1 What are the SI units of the wavefunction Ψ(x).I know that [Ψ(x)]^2 describes the probabilty of finding a quantum object at a certain quantum state but what about the wavefunction instead? 1 answer · posted 1y ago by MissMulan‭ · last activity 4mo ago by Anyon‭ 33% +0 −2 Suppose we have a free falling object inside a planet's gravitational field with strength g.The planet's atmosphere provides a drag force which is dependant from the u^2 of the particle. Suppose t... 0 answers · posted 1y ago by MissMulan‭ · edited 1y ago by MissMulan‭ 25% +0 −4 Suppose we are using a force gauge to measure gravity in a planet. We set the gauge force to the 1N range which has a resolution of .01 N. From its specs the error introduced during the measurmen... 0 answers · posted 1y ago by MissMulan‭ 50% +0 −0 What examples of a system can be described by a system of ordinary differential equations? 1 answer · posted 1y ago by MissMulan‭ · last activity 1y ago by Olin Lathrop‭ 25% +0 −4 Im designing a capacitor and I have decided to make the surface of 1 plate of the capacitor bigger than the other plate. How are the charges sorted through A2?Are they spread out to cover all th... 0 answers · posted 1y ago by MissMulan‭ 50% +0 −0 Get 2 conductors and seperate them we can use Gauss's law to calculate the capacitance created by the seperation of the 2 conductors.Can we use other laws of electromagnetism to calculate the induc... 2 answers · posted 1y ago by MissMulan‭ · last activity 1y ago by TonyStewart‭ 50% +0 −0 If we have a LC high pass filter the transfer function H(s) becomes: $$H(s) = \cfrac{sL}{sL + \cfrac{1}{sC}}$$ If we solve for s to find a pole of the transfer function we get: $$s = j \cfrac... 0 answers · posted 1y ago by MissMulan‭ · closed 1y ago by MissMulan‭ 25% +0 −4 These WorldFamous companies advertise that their lenses can control myopia for kids, NOT adults. But none of these lenses are approved by FDA. I asked my optometrist why merely kids, not adults. Bu... 1 answer · posted 1y ago by TextKit‭ · closed 1y ago by Mithical‭ 33% +0 −2 My optometrist said that round eyeglass lenses are OPTICALLY better than rectangular, particularly to correct myopia. He was NOT referring to fashion or style. I couldn't understand his explanatio... 1 answer · posted 1y ago by TextKit‭ · edited 1y ago by TextKit‭ 50% +0 −0 With time dilation a cosmonaut could travel forth in time, especially in light speed. But are there much lesser speeds which might be achievable by humans in the next 100 years which could also in... 0 answers · posted 1y ago by deleted user 33% +0 −2 I never grokked the optics behind LightHouses and the WW2 poster below work. LightHouse beams are narrow and focussed. Doubtless, the light source can fail to illumine a seafarer or the enemy subm... 1 answer · posted 1y ago by TextKit‭ · last activity 1y ago by Olin Lathrop‭ 28% +0 −3 Please see below screenshot of 15:59.The LED spot light (fastened to the front of the boat) illumines merely a few meters in front, and fails to illumine most of the water between the boat and the... 1 answer · posted 1y ago by TextKit‭ · last activity 1y ago by Olin Lathrop‭ 60% +1 −0 I'm interested in knowing the surface temperature of both sides of a double-pane or triple-pane window. Given the R-value of the window, and the air temps outside and inside, how can I calculate t... 1 answer · posted 1y ago by re89j‭ · last activity 1y ago by Olin Lathrop‭ 66% +2 −0 I want to write some code to control my whole house humidifier. I want my code to calculate the percentile relative humidity above which dew will form on my windows. I have sensors for air tempera... 0 answers · posted 1y ago by re89j‭ 40% +0 −1 I was looking for book on classical thermodynamics. I found lot of related posts in PSE but couldn't find a book which type I was expecting. I was searching for book which covers the whole thermody... 0 answers · posted 1y ago by deleted user · edited 1y ago by deleted user 60% +1 −0 In the lab I changed the angle the light hits a photoresistor and it doesnt obey Lambert's cosine law the conductivity of the photoresistor drops fast from +-20 to +-30 degrees angle.Why? 1 answer · posted 1y ago by MissMulan‭ · last activity 1y ago by Olin Lathrop‭ 75% +4 −0 The Rayleigh-Jeans law does a good job of describing the spectral radiance of a black body at low frequencies:$$B_{\nu}(T)=\frac{2kT\nu^2}{c^2}$$with T the temperature and \nu the frequency... 1 answer · posted 1y ago by HDE 226868‭ · last activity 1y ago by Derek Elkins‭ 60% +1 −0 May it be that there are more than 8/9 planets in our solar system which aren't detectable with the current technologies? Is there any theory suggesting that our solar system has more planets, all... 1 answer · posted 1y ago by deleted user · last activity 1y ago by Canina‭ 60% +1 −0 In classical physics book of kleppner, i read that An atom can "jump" from one stationary state a to a lower b by emitting radiation with E_a-E_b. The frequency of the emitted "package of radi... 1 answer · posted 1y ago by deleted user · last activity 1y ago by Olin Lathrop‭ 71% +3 −0 I know that equation for parallel resistance is$$\frac{1}{r_{tot}}=\sum_i \frac{1}{r_i}$$But i wonder to see equation of series spring constant. If we add multiple spring in series. Then their ... 1 answer · posted 1y ago by deleted user · last activity 1y ago by Olin Lathrop‭ 50% +0 −0$$\begin{alignat}{2} && \vec \nabla \cdot \vec D & = \rho_f \\ & \implies &\int_V \vec{\nabla} \cdot \vec D \mathrm d\tau & = \int_V \rho_f\ \mathrm d \tau \\ & \impl... 1 answer · posted 2y ago by deleted user · last activity 1y ago by deleted user 71% +3 −0 I was recently reading some questions here and there saying that "relativistic mass is outdated". I saw someone saying that "outdated" doesn't mean the concept is wrong. My question is what physici... 1 answer · posted 2y ago by deleted user · edited 4mo ago by Reinstate Monica on Stack Exchange‭ 50% +1 −1 I was looking for equation of motion. I came up with a solution but it doesn't satisfy me. Cause I was trying to find motion of that particle using Lagrangian. We know that $$W=\int \vec F\cdot d\... 1 answer · posted 2y ago by deleted user · edited 1y ago by deleted user 20% +0 −6 IKEA discontinued this NOVEMBER lamp in 2007, but I still use it. IKEA confirmed that they did not intend or design any cover or share with this lamp, and the light bulb is supposed to be exposed. ... 2 answers · posted 2y ago by TextKit‭ · last activity 2y ago by celtschk‭ 71% +3 −0 Momentum is proportional to an object's velocity, and kinetic energy is proportional to the square of its velocity \dfrac{mv^2}{2}. It's pretty intuitive that if object B is going twice as fast a... 3 answers · posted 2y ago by gmcgath‭ · last activity 2y ago by celtschk‭ 50% +1 −1 Which one is correct?$$E=mc^2$$or$$E^2=(mc^2)^2+(pc)^2$$I mostly seen$$E=mc^2$$from my childhood, and when I was learning problem solving in relativistic mechanics I had seen$$E^2=(mc^2)^2... 1 answer · posted 2y ago by deleted user · edited 1y ago by deleted user 60% +1 −0 All given metrics are for orthonormal-basis. 2 dimensional spacetime : I saw that Minkowski Metric looks like this : $$\pmatrix{-1 & 0 \\ 0 & 1}$$ or $$\pmatrix{1 & 0 \\ 0 & -1}... 1 answer · posted 2y ago by deleted user · edited 2y ago by deleted user 42% +1 −2 Are there areas in the observable universe which surely cannot contain galaxies with planets that can support life as we know them? 1 answer · posted 2y ago by deleted user · last activity 2y ago by Olin Lathrop‭ 50% +0 −0 I saw following equation in Griffiths EM$$V(r)=-\int_\mathcal{O}^r \vec E \cdot d\vec l$While the surface was closed but not symmetrical circular. At first I was thinking$\mathcal O$was repr... 1 answer · posted 2y ago by deleted user · last activity 2y ago by deleted user 30% +2 −7 Two weeks ago, my carry on worked perfectly. But last week the detachable wheels stopped rotating smoothly, when I tried to glide my carry on. The wheels budge JUST A TAD when you push them hard, b... 0 answers · posted 2y ago by TextKit‭ · last activity 2y ago by deleted user 71% +3 −0 If I have a rocket with some known number of engines$n$, each producing thrust with arbitrary direction$T_n$and center of thrust$r_n$, the total thrust amount and direction$T_{total}\$ is equal...

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