# All Questions

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### Wind turbine impact on cars fuel consumption [on hold]

I have question that I still can't resolve. How much cars fuel consumption rises(l/100km) if I attach 1 kW wind generator to cars body? How can I calculate that and what do I need to know? ...
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### If there are two conserved quantities that do not commute, why is there typically another?

I have come to the following conjecture: Consider two observables $A,B$ that do not commute and represent conserved quantities, there is typically a third conserved quantity. E.g. for some ...
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### Calculating rocket thrust [on hold]

for my recent project I'm trying to compute somewhat accurate rocket physics (although approximations are good enough - for example for aerodynamics). The project is about making "game-like" ...
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### Travel time in combined driving/walking trip [on hold]

A car is sent to take a student from coaching every day. The car arrives at the coaching 15min before the time. One day coaching gets closed one hour before the usual time. Then the student without ...
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### Representing Hamiltonian in discrete position basis

I am trying to numerically find eigenstates of an Hamiltonian. Let $V(x)$ be some potential. Suppose my space is between $-L,L$ and that the allowed positions are every $\Delta x$, such that ...
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### Beam of light from glass to air

I am reviewing some concepts on light and came across a question that puzzled me. A beam of light is incident from a glass into air. The incident ray is 60 degrees to the normal. The question actually ...
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### Translational Velocity

Is the translation velocity equivalent to its real velocity or radial velocity? Online sites and textbook are saying different things, So Im not too sure what is going on
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### Damped oscillator: time-reversal, time-translation and dissipation

The equation of motion of a damped oscillator $$\frac{d^2x}{dt^2}+\gamma\frac{dx}{dt}+\omega_0^2x=0$$ which is invariant under time-translation $t\rightarrow t+a$, but not under time reversal ...
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### Floating of a dead body [on hold]

Why does a dead body float on water? And why does it float by making head downward? The dead body floats due to the production of gases. But how are the gases produced? And which gases are produced? ...
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### Unification of Newtonian gravity and electrostatic force [on hold]

Can we not unify Newtonian gravity & electrostatic force? All properties are almost same. We can imagine the atoms of the Earth's core to become dipoles when a body is freely-falling. Thus, due to ...
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### Can charged scalar have non zero vev?

In Higgs-Kibble mechanism, if we consider a SU[2]_L doublet of complex scalar fields, then one of them is charged and the other neutral. Why does the neutral field acquire vev and not the charged one? ...
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### The state below has non-zero entanglement, but why is its discord zero? [on hold]

|ψ⟩=(|00⟩+|11⟩)/√2. after calculation, I get $\delta=cos^2(\theta)\log cos^2(\theta)+sin^2(\theta)\log sin^2(\theta)$, Its minimum value is 0, therefore the discord of the state is zero. But there is ...
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### Relation between phase of dark field and bright field images

I am trying to understand how the super-resolution technique based on Fourier Ptychography 1. In the paper, we run phase retrieval algorithms using images captured using illumination at different ...
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### Ohm's law and an ideal voltmeter

In an ideal voltmeter there is infinite resistance so because of which no current is flowing through it and the voltage reading is not affected. The ohm's law stated that V = I * R In an ideal ...
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### What does a one-photon state look like as a wave functional?

According to a post on a mailing list here: https://groups.google.com/d/msg/sci.physics.research/n7Ao7N9aeq0/wqgj20-jBQAJ In general, quatum states |Psi> of the electromagnetic field, no matter ...
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### Has Rovelli proven that time doesn't exist? [on hold]

Has Rovelli proven that time doesn't exist? See this paper on the Arxiv for a description of his ideas. I am reading some people argue at length, and inauspiciously, that he has. I am entirely ...
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### What is the size/mass of largest metal plate that was moved by casimir effect?

I learned about Casimir effect recently. Is it applicable only on very light/thin metal plates( in terms of micro/nano meters) or is the effect large enough to be noticed on mili meters scale? What is ...
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### Could science still exist if the nature of events in the universe would be truely random? [on hold]

Most of the science is based on the study of how something behaves in a well defined pattern. Everything follows a rule. Which is the base of all scientific studies. So, in case if there won't be any ...
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### Find the Work Done in this system [on hold]

In Inclined plane if friction force = the weight of the object. What is the total work done by this system?
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### How do (special) groups such as U(1) and SU(2) do represent the electromagnetic and weak forces? [on hold]

I don't see how groups, such as the circle group somehow representing electromagnetism, represent the fundamental forces. Where is this connection between maths and theoretical physics? Also, as a ...
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### Will this evaporative cooler work? [on hold]

I have just started o doing a thesis which is basically designing for developing countries…..The idea that I have is based on the zeer pot cooler….It is more or less attached to what is basically a ...
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### How one can count how many phonon modes is there in the crystal?

I'm reading the review on phonon and Raman scattering in 2D transition metal dichalcogenides (2D TMDCs). At the beginning of Section 2.1 it is said that, since there are two X-M-X units in the ...
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### Is it because of curvature of time that an non-moving object starts to fall down? [on hold]

Are there two extremes in general relativity? One, in which the object is at rest, and starts to fall by time curvature, and one in which light is only influenced by the curvature of space?
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### Volume of Air pumped in Isothermal system [on hold]

A manual bicycle tire pump has a cylinder with volume V. When the piston is extended, the valve to the tire closes, and air at atmospheric pressure enters into the cylinder through another valve in ...
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### How is the Earth moving in a elliptical orbit around the Sun? [duplicate]

If gravity is transmitted by a four-dimensional fabric of spacetime and the Sun creates a bend in it ,which causes planets to orbit it , shouldn't the planets move in a circular orbit around the Sun ...
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### What is the BG Equation?

About 45 years ago or so I was a Physics department staff computer programmer when I was a physics major undergrad. I worked with a professor doing research on nuclear shell models -- he was ...
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### Why are dimensions regarded as square/perpendicular?

Starting from the second dimension, the dimensions are basically represented by a square, cube, tesseract, and so on. I don't know if this is a stupid question or not, but is there an obvious or ...
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### Does a cathode ray tube emits electromagnetic waves from a steady DC electron beam?

In cathode ray tube, heated cathode emits stream of electrons but when I wrap a coil around tube a current will be inducted in that coil? after all electron beam is a steady DC current? so no emf?
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### Characteristics of EMF [on hold]

EMF Characteristics of Chemical,Magnetic,friction,Piezoelectric,Photoelectric and Thermocouple also advantages and disadvantages and used for.
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### Why is weak hypercharge not a function of the number of up or down quarks?

I'm fairly new to quantum mechanics, and I was looking up some basic information about the weak force and it's interactions. I found this equation of weak hypercharge on Wikipedia and quoted a few ...
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### What is $\beta^-n$ decay?

I'm looking on the nndc chart of nuclides and am seeing $\beta^-n$. What is this? http://www.nndc.bnl.gov/chart/reCenter.jsp?z=3&n=6
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### finding the plane of cleavage in crystals [on hold]

The crystal can be clear such as diamond or shiny like germanium or metallic like galena or fools gold. I would like to cut some of these cleanly along natural cleavage lines. I would also like to ...
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### Is the self-interaction mass of a geon related to the mass gap? [on hold]

I wrote in the question about how type II and III solution have longitudinal components and are related to a geon. This mass has a similarity to the mass gap in gauge theories. In light of the ...
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### Query about Ramond-Ramond fluxes associated with a Dp-brane

A paragraph in the string theory book by Ibanez and Uranga (String Theory and Particle Physics by Luis Ibáñez and Angel Uranga) has confused me. According to the book (for a screenshot of the ...
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### Fermi-Dirac distribution - holes and electrons

The density of probability of an energy state $E$ being occupied by an electron is $$f(E,T)=\frac{1}{1+e^{\frac{E-E_F}{kT}}}$$ and the density of probability of an energy state being occupied by a ...
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### Solving ODE with essential singularity [migrated]

I would like to solve the following linear ODE. $y''(x) -\frac{2}{x} \frac{1-3x^4 +2x^3}{1+3x^4-4x^3} y'(x)+\frac{\omega^2}{(1+3x^4-4x^3)^2} y(x) = 0$ Here $x$ is a dimensionless variable which runs ...
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### How can an electron's magnetic moment precess around the direction of an external magnetic field?

I am reading this article: The Nature of the Electron by Don Lincoln in The Physics Teacher, Volume 54 (2016), pg. 203, and I ran across the part where he talks about measuring the magnetic moment of ...
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### Will the speed of gravity and the speed of light always be the same?

I have been considering the following though experiment: If the entire sun were to disappear at once, would we feel it first due to the sudden drop in gravity or see it first? The answer I have come ...
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### Partial Differentiation without chain rule in Euler Lagrange Equations [duplicate]

The Euler-Lagrange equations for a bob attached to a spring are $$\frac{\mathrm{d}}{\mathrm{d}t}\frac{\partial L}{\partial v} = \frac{\partial L}{\partial x}$$ But $v$ is a function of $x$. Is it ...
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### Derivation of Lagrangian [duplicate]

Actually I am beginning to study Lagrangian and Hamiltonian Mechanics. The book that I am considering directly introduces the Lagrangian L=T-V. Though further on the book , the Euler Lagrange ...
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### Can someone explain me magnetic potential? [duplicate]

I don't understand why we can write the magnetic field as a potential vector A, and what exactly this potential is. Is it just a mathematical thing? And how can it help me calculate the magnetic ...
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### How are boundary consitions implemented correctly in time dependent hydrodynamics?

I posted this question more than one year ago and got an answer recently. This answer looks good to me, but indicates that something is wrong in my original approach to the problem. Can someone tell ...
Wich is the relation between mass and spin? If I have a particle that is formed by the quarks $ud^{*}$, if its spin is $0$, the mass of this particle will be smaller than the mass of the particle ...