# All Questions

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### Physical distribution of salt anions and cations during electrophoresis

If I have a volume of $L$ liters of salt water at a concentration of $\approx N$ mM NaCl and I pour it into an electrophoretic apparatus (like this one: ). Once we turn the apparatus on, and set the ...
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### How can I split a resultant force into its $x$ and $y$ components?

Point charge 3.5μC is located at x = 0, y = 0.30 m, point charge -3.5μC is located at x = 0 y = -0.30 m. What are (a)the magnitude and (b)direction of the total electric force that these charges ...
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### What is the opposite of the Planck length?

What "large size" unit of length could be considered at the opposite end of spectrum from Planck's length? Is there a table of smallest and largest value for various physical quantities that can be ...
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### What is the space/time effect of an exploding supernova?

If the flow of energy -- or the flow of time/light/space? -- in "empty" space is distorted when meeting an object such as a planet, flowing around the object in a distortion of space/time that also ...
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### What is the scalar field mediated force?

I'm working on a paper about symmetron cosmology. Symmetron is a scalar field that by its symmetry breaking can explain the dark energy. the action is: ans A , V are assumed to be: where M ...
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### How cold would a bowling ball near absolute zero make a room?

If a bowling ball at absolute zero suddenly appeared in my room, how cold would the room get? Would I die? My initial estimation is that it one bowling ball at 0K (i.e., 300K below room temperature) ...
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### Quantum Yang-Mills Theory and AdS/CFT

I just read the first chapter of Becker-Becker-Schwarz. To quote: A remarkable discovery made in the late 1990s is the exact equivalence (or duality) of conformally invariant quantum field ...
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### Does the pressure in a pressure tank depend on the amount of air?

I have a pressure tank which is filled with water and air. What want to know is: if I change the ammount of air in the tank would the ammount of water that leaves the tank, when pressurized, change?
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### Thermodynamic relations from Gibbs-Duhem

Given the Gibbs-Duhem relation $V dp = S dT - N d \mu$, I am having trouble deriving the following identity: $\ (\frac{\partial N}{\partial \mu})_{V,T} = N (\frac{\partial \rho}{\partial p})_T$ ...
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### Which force is responsible for victory in tug of war?

I'm confused: In a tug of war game on rough ground who will win? The one who applies greater force on the rope or the one who applies greater force on ground?
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### Calories Burned While Hiking

I want to find out how many calories are burned on any particular hike by any particular by using a formula. I figure it's probably a simple physics question, but since I never took physics, I don't ...
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Say there is a horizontal rod, where a force $P$ is applied to the right hand side of the rod to drag it horizontally to the right. If I drew a force diagram, I'd put some vector with a length of $\| ... 1answer 153 views ### What determines how much electrical charge an object can hold? What determines how much electrical charge an object can hold? Does increase voltage force more electrical charge to be store in an object (Van de Graaff generator), since electric field increase as ... 0answers 8 views ### mass of small fluctuation around vacuum for a potential V, how we define the mass of small fluctuation around its vacuum? for example I have the potential what is the definition of mass of small fluctuation around the symmetry-breaking ... 1answer 16 views ### Can an arrangement of particles be duplicated precisly? Is it possible to teleport or clone someone or something? After watching this TED talk by Max Tegmark - https://www.youtube.com/watch?v=GzCvlFRISIM I find myself wondering if it is then possible to ... 0answers 11 views ### Why photon has a wave nature? Wave theory does not account for the photon model, which was developed only to explain quantum effects like photoelectric effect. Then why do we talk about a photon's reflection and rarefaction, as ... 2answers 41 views ### Bragg diffraction and lattice planes Crystalline substances show, for certain sharply defined wavelength and incident directions, very sharp peaks of scattered X-ray radiation. From the illustration below we see that we get constructive ... 0answers 12 views ### Angular and Linear Acceleration Imagine a rod attached at one end to a solid wall. It has a hinge where it is attached to the wall, which allows it to rotate. Hold the rod perpendicular to the wall. In the instant you release it, ... 2answers 318 views ### How does escape velocity relate to energy and speed? I have several confusions regarding escape velocity. I am sure I am missing something(s) obvious or maybe I am taught wrong. Lets say we throw an object of any mass at exactly escape velocity of ... 4answers 4k views ### What does the magnitude of the acceleration mean? I am a little confused as to what the magnitude of acceleration is and what it means. 7answers 4k views ### Cyclist's electrical tingling under power lines It's been happening to me for years. I finally decided to ask users who are better with "practical physics" when I was told that my experience – that I am going to describe momentarily – prove that I ... 1answer 19 views ### Can someone explain effects of time dilation on expansion of universe I'm not a physics guy, but this is something I have always wondered about. If a clock flown by an object of high mass runs slower, what is the effect of this in regards to the density of the universe. ... 2answers 198 views ### Wave function for an electron in and around s small charged sphere I am interested in solutions of the Schroedinger equation. For simplicity I started my studies with the$n=1$ground state of the hydrogen atom. I was particularly interested in the higher moments of ... 0answers 21 views ### How to convert 1atm to kj/m3 [on hold] I am trying solve similar questikn like this myweb.loras.edu/cm418218/EGR334/HW%2019%20Solutions%20Spring%202012.docx 13th slide but in si unit i just want to know how to convert 1atm to kj/m3 in ... 2answers 565 views ### Long time deviations from exponential decay in radioactivity Are there any examples of common substances whose decay is not exponential? We're used to thinking about radioactivity in terms of half-lives. This is a concept that makes sense only for a decay that ... 0answers 28 views ### How can light travel at speed of light? [duplicate] I am well aware that the speed of light is a universal constant at which nothing but light can travel. But why? Why can even light travel at such a speed? Our maths tell us that anything with rest ... 0answers 26 views ### Can you please tell me what's wrong with my calculation? [on hold] I'm taking second level physics at the university. Here's an exercise I've been working on and wasn't able to get the right answer for: In the figure take$q_{1} = 69μC$,$q_{2} = -32μC$, and ... 1answer 13 views ### World-sheet energy-momentum tensor and OPE On p43 of Polchinski's book, it says that under the world-sheet translation$\sigma^a\rightarrow\sigma^a+\epsilon v^a$,$X^\mu\rightarrow X^\mu-\epsilon v^a\partial_a X^\mu. And $$j^a=iv^b T_{ab},$$ ... 1answer 21 views ### What exactly happens to an exposed human body in space? I know that space is a vacuum, has no air and is very, very cold. from what i have seen in movies and TV shows when a space suit is exposed the oxygen will escape will escape like a visible gas and ... 15answers 2k views ### What are the mechanics by which Time Dilation and Length Contraction occur? What are the mechanics of time dilation and length contraction? Going beyond the mathematical equations involving light and the "speed limit of the universe", what is observed is merely a phenomenon ... 2answers 347 views ### Does a current-carrying wire running through the centre of a solenoid experience force? Imagine looking at a solenoid from above. Current passing is through it in a clockwise direction. The direction of the field lines therefore is towards the bottom of the solenoid. Now pass a straight ... 0answers 16 views ### Algorithm of Patankar for Numerical Heat Transfer and Fluid Flow [on hold] I look for the algorithm of Patankar (for exemple: SIMPLE, SIMPLER, ... 2answers 59 views ### Circular motion and time dilation Einsteins' time paradox was shown when two atomic clocks were synchronized and one was sent in a super sonic plane and the other kept at rest. When the two where then checked it was shown that yes ... 2answers 2k views ### Realistic calculation of heat loss for pipe Good day everyone, I am new on this site and I hope to find here help, since I am not going anywhere with the literature I have found. I try to calculate realistically the heat loss of a hot, ... 6answers 778 views ### Could the Schrödinger equation be nonlinear? Is there any specific reasons why so few consider the possibility that there might be something underlying the Schrödinger equation which is nonlinear? For instance, can't quantum gravity (QG) be ... 0answers 25 views ### Minkowski spacetime vs Euclidian space Two questions marked in bold: What is the magnitude of a Minkowski spacetime four vector? I'm deducing that it is c for all observers, and that it is a velocity vector. In Euclidian space, a ... 2answers 127 views ### Disconnected aileron/surface deflection in terms of speed? Would a disconnected surface, especially aileron, deflect upwards as you slow down due to increased alpha? I figure out it is more likely to deflect upwards as you increase your airspeed, thus having ... 2answers 211 views ### Misaligned Mirror on Michelson Inferometer If one of the outer mirrors on a Michelson interferometer was to be misaligned by a small angle of theta, what would be the shape of the interference pattern in the detector plane? What would happen ... 1answer 45 views ### Microscopic understanding of Brewster angle The textbook explanation is that, at Brewster's angle, the electric dipoles excited by the incident light can't reradiate to the reflection direction since it's aligned with the dipole moments. Is ... 2answers 304 views ### Circularly polarized light incident at Brewster's Angle If a perfectly circularly polarized wave of light is incident on a dielectric medium (coming from air) at Brewster's Angle, what will the polarization state of the transmitted wave be? I am aware ... 0answers 6 views ### Convention about delta x in Waves Interference http://imgur.com/oxFF7q8 They seem to adopt a convention that delta x must always be positive. Otherwise, there is no way to know what the phase difference of the sources actually means. Does a ... 1answer 37 views ### Would equations for a spinning top be an (x,y,z) vector [duplicate] I am following the equations on this page, and for torque it ismgr\sin\theta$, but I am curious about$r$. I am working on a game and I want to correctly model the top, and am curious if$r$should ... 1answer 20 views ### Reflected waves and phase changes If a wave passes from a lightweight string to a higher density string, we say that the reflected wave has a pi phase change. Can we say that it has minus pi phase change? If yes, why would that not ... 1answer 168 views ### Pipe in a flowing river problem I'm working on a certain problem in fluid mechanics, which isn't really my strongest area. The problem is as follows: Curved pipe is partially submerged in a flowing river so that one end is pointing ... 2answers 78 views ### How quickly should a fluid come to hydrostatic equilibrium? Let's say I'm holding a one-liter water bottle, full of water, which I then drop. Before dropping the water bottle, the equilibrium is for there to be a pressure gradient in the water canceling the ... 0answers 23 views ### Supergravity solution, metric for the total space, and connection In supergravity solutions, one sometimes encounters the case where the manifold may be a bundle over some base space, and one has to write down the explicit metric regarding such bundle. I would like ... 1answer 46 views ### Refractive index of dielectric in different frames of reference The setup A transparent isotropic dielectric medium moving in the negative$x'$direction at speed$v$in frame$S'$is stationary in frame$S$, where it has refractive index$n\$. In other words, ...
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In AdS/CFT, the story of renormalization has an elegant gravity dual. Regularizing the theory is done by putting a cutoff near the conformal boundary of AdS space, and renormalization is done by ...