# All Questions

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### mechanical strength [on hold]

Question asks Each of the two aluminum bars is subjected to a torque of magnitude $T = 150$ Nm. Knowing that$G = 26$ GPa, determine for the bar: The maximum shearing stress and its ...
34 views

### Are images of three-dimensional objects also three-dimensional?

Suppose that I produce an image of a dog using a converging lens. I can draw ray diagrams for the nose of the dog as well as the back leg. These are definitely longitudinal points, not transverse. ...
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### Are composite bosons always bosonic (e.g. the pion-cloud surrounding the nuclei)?

The $\pi$-meson is a boson, but consists of quark-antiquark (fermions). It seems to me that at some energy level (equivalently distance) the inner structure (fermionic nature of the quarks) of the ...
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### Can a glass window protect from heat radiation?

I have been reading in this and found a statement saying : " Glass will not transmit heat radiation.". So now I am confused. If glass won't transmit heat radiation, then why do we feel hot when we sit ...
31 views

### Thermal physics problem (slow expansion in a evacuated bottle) [on hold]

An evacuated bottle with non conducting walls is connected to a gas holder of essentially infinite volume, and which contains helium at a pressure of $P_o$ and temperature $T_o$. Helium bleeds ...
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### Why Inox Steel doesn't interact with magnets?

My dad has a HUGE magnet on his workshop. I love magnets, and when I saw it, I asked him what it was for. His reply was: "I don't know why, but inox steel bolts don't get attracted to it, so I use ...
34 views

### Experimental evidence for non-abelian anyons?

Since non-abelian anyons have become quite fashionable from the point of view of theory, I would like to know, whether there has actually been experimental confirmation of such objects. If you could ...
29 views

### reduced charge for attracting electrons?

The reduced mass in the two body problem is $\mu= \cfrac{m_1 m_2}{m_1 + m_2}$. Is there any analog to this with interacting charged particles (or at least that is of use somewhere in physics)? I have ...
51 views

### Temperatures at extreme densities

Cosmology (and astrophysics) talk about the "initial singularity" (IS, became the big bang) and "black hole singularities" (BS, inside black holes), and these appear to be quite different: The IS is ...
102 views

### Wave function of a particle in a gravitational field

Suppose we have a particle with mass $m$ and energy $E$ in a gravitational field $V(z)=-mgz$. How can I find the wave function $\psi(z)$? It should have an integral form on $dp$. Any help would ...
37 views

### Experiment dropping electrons into glass of protons

So, when you drop dye into a glass of water the dye spreads out. Now I realize you cant simply replace the water in the glass with protons (or a pure concoction of electrons) but I am wondering... ...
58 views

### Does an electric field create a pH gradient?

Since pH is a measure of the effective concentration of $\mathrm{H}^+$ ions a solution, I expect that an electric field applied to a solution will create a pH gradient. The higher concentration of ...
53 views

### Velocity and acceleration in SHM

Can velocity and acceleration reach maximal values during the SHM simultaneously? Can you explain why?
60 views

### Are pure mechanical evanescent waves possible?

Consider a lattice of massive points connected by harmonic springs, with zero or periodic boundary conditions. If we make a repeating pattern of $N$ varying masses, the system will have $N$ bands of ...
128 views

### Is optical-illusion responsible for Loch Ness monster? [on hold]

When you look out at the white-caps on a wind-swept lake, you can see a dark, undulating pattern under the crests of the white-caps. Could this shadow-like area explain the sightings? Edit First of ...
20 views

### Help Understanding Equation for Characteristic Time of Induced Magnetic Field

I am reading this book, the part in particular about Eddy-current separation starting at Page 246, in it there is an equation for calculating the "characteristic time with which the induced magnetic ...
15 views

### Using piezoelectiricty to produce electricity

What if piezoelectric materials could be placed under a runway to then produce electricity to power (street) lights - I don't know what voltage certain piezoelectric compounds can produce, but would ...
24 views

### Cosmological and gravitational redshift in physics

I am interested in knowing what are the differences between gravitational and cosmological redshifts?
36 views

### modern physics numerical [on hold]

A 100 ml solution having activity 50 dps (disintegration per second) is kept in a beaker.It is now constantly diluted by adding water at a constant rate of 10 ml/sec and 2 ml/sec of the solution is ...
53 views

### Friction acting on mass on string

Assume we have some stationary point mass that would slide, if not for some coefficient of friction, along a light, inextensible string, attached to two points at different heights. Considering ...
61 views

### why do we get continuous intensity in spectra?

we know energy levels of a molecule is discrete. So we should get only sharp peaks for any spectra. But in most of the spectra I see a continuous intensity? why is so? In the following spectra the ...
63 views

### What happens when a black hole dies?

It just vanishes into space leaving nothing behind or does it expel some material? Also, talking more about black holes, as far as i understand the term "temperature", it is defined by the amount of ...
29 views

### Light pulses and energy-time uncertainty principle [duplicate]

Suppose we have a monochromatic light beam. We put an obstacle between source and observer and remove it repeatedly by certain frequency such that observer sees an oscillating intensity of light. Will ...
18 views

### climate change influence diel air temperature variation [on hold]

Are there any peer reviewed papers that highlight the change in the diel air temperature change as a response to climate change? for example, if air temperature is expected to increase with climate ...
39 views

### If my neighbor connected $100\: \mathrm{kV}$ power line to the piped tap water, would it kill me? [on hold]

I'm just wondering, if someone put a very high voltage power to the piped tap water, would it going to be dangerous to the neighbors?
61 views

### Why does a light wave invert at a boundary with greater index of refraction?

Is there a reason why a EM wave reflects invertedly when it meets a boundary point with a greater index of refraction. In the case of ropes, if remember correctly, the reason why it inverts is to ...
38 views

### 1-dimension radiation problem [on hold]

A positive charge $q$ is fired head-on at a distant positive charge $Q$ ( which is held stationary ), with an initial velocity $v_{0}$. It comes in, decelerates to $v=0$, and returns out to ...
23 views

### How can a qubit superposition state be written to a quantum register?

If a 3 qubit register can simultaneously store all 8 possible values in superposition, then how it is achieved to write 8 values in to the register? And How these 8 values can be processed parallel to ...
103 views

### Proof that the ground pushes you up

(Excuse me if this is obvious because I am new to physics) It has been said that when you try to jump you are exerting your force on the ground and the ground pushes you up. I was wondering if this ...
118 views

### Why isn't temperature frame dependent?

In (non-relativistic) classical physics, if the temperature of an object is proportional to the average kinetic energy ${1 \over 2} m\overline {v^{2}}$of its particles (or molecules), then shouldn't ...
48 views

### Vibrational anharmonic coupling and noise-induced spontaneous symmetry breaking in a hexagonal finite mechanical lattice

Happy holidays, everyone! The following is part question, part visual gallery, and part classical mechanics problem. Inspired by snow over the weekend I began simulating the vibrations of the ...
440 views

### How to measure resistance of a piece of wire?

My son is doing a science experiment on how varying temperature and diameter of wire impacts the resistance. We are assuming we can accomplish this by using different gauge wires, a home thermometer, ...
53 views

### Is there a minimum mass is required for light to be noticeably bent?

The sun bends the trajectory of light slightly. And a black hole will bend the trajectory entirely. This is all dependent on the proximity to the source of gravity. For a given angle, is there some ...
119 views

### Conservation of Mathematical Constraints when deriving Energy and Momentum from F=ma

Background: Starting from $F = ma$, integrating with respect to time, and using basic calc, one can derive $\int Fdt = m (v_f - v_i)$ Starting from $F = ma$, integrating with respect to distance, ...
33 views

### Doppler effect question [on hold]

I have this question regarding the Doppler effect. I have been trying to do this question for the longest time, but I cant seem to solve it. Imagine you are standing between 2 ambulances, one ...
32 views

### Calculation of linear / angular velocity via force and distance [on hold]

I have a force and distance vector. I know that linear velocity and angular velocity depend on how much it goes through the CM, and how much it doesn't respectively. I know that the cross product of ...
41 views

### What is the importance of the Odderon?

From hep-ph/0001149v1: (1) an Odderon contribution is absolutely necessary to reproduce quantitatively well the data; while its presence is not explicitly needed at $t = 0$, its inclusion is ...
22 views

### an Abelian complex statistical phase from exchanging non-Abelian anyons?

We have some discussions in Phys.SE. about the braiding statistics of anyons from a Non-Abelian Chern-Simon theory, or non-Abelian anyons in general. May I ask: under what (physical or mathematical) ...
117 views

### What is the reasoning behind the Hill Sphere?

According to Wikipedia, Hill Sphere is : the volume of space around an object where the gravity of that object dominates over the gravity of a more massive but distant object around which the first ...
28 views

### Spring problem? [on hold]

I came across this problem in physics "Physics for Scientists and Engineers with Modern Physics by Serway" A block on the end of a spring is pulled to position $x = A$ and released from rest. In ...
57 views

### Specify the Stress Energy Tensor and Calculate the Curvature

I have a simple question about general relativity and the Einstein field equations, I wonder if you can specify the stress energy tensor, i.e. specify some mass distribution in space and then ...
21 views

### Heat transfer by radiation and glass absorptivity [on hold]

Does glass absorb infrared radiation significantly? That is, what is the absorptivity of glass to infrared radiation in general?
53 views

### The expansion of a function in powers of a parameter

In the perturbation theory for non-degenerate levels, the energy $E_n(\lambda)$ of an eigenstate $|\psi_n(\lambda)\rangle$ of the hamiltonian $\mathcal{H}=\mathcal{H}_0+\lambda \mathcal{H}_1$ (where ...
40 views

### Collection of histories vs. collection of momentary configurations

For a given Hamiltonian, is the space of histories of a classical system the same as the symplectic manifold? Do I have to take care of gauge equivalences and if so, is this only an issue for fields ...
22 views

### Thermal expansion and conductivity

When thinking about how the lattice constant of silicon can be given up to eight decimal places without a remark for the temperature I realized that, it seems most insulators and semiconductors seem ...
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### How to use the WKB approximation to find wave functions?

I'm trying to learn how to apply WKB. I asked a similar question already, but that question was related to finding the energies. Here, I would like to understand how to find the wave functions using ...