0
votes
0answers
15 views

Volume of phase space

Consider the micro-canonical description of an extreme relativistic ideal gas of N particles in three dimensions, characterized by the energy-momentum dispersion E = pc. Compute the volume of the ...
0
votes
0answers
12 views

Triple delta potential [on hold]

I'm looking for the bound energy of a triple-delta potential: $V(x) = -w \left [ \delta(x-a) + \delta(x) + \delta(x+a) \right ]$ My wave function is $\psi_1(x) = A e^{\kappa x}$ for $x < -a$, ...
0
votes
0answers
10 views

Matrix forms to understand a state transition operator

Given an equilibrium of two states.$\left| 00 \right> \rightleftharpoons \left| 11 \right>$. And introduce a map $\mathcal{B}(\mathbb{C}^2\otimes \mathbb{C}^2) \rightarrow ...
1
vote
1answer
18 views

Free Energy, Avialable Work in a reversible process

I was reading the Wikipedia page on Helmoltz Free Energy, http://en.wikipedia.org/wiki/Helmholtz_free_energy, and run across a point I cannot unravel. The discussion goes as follows, I reproduce it ...
0
votes
1answer
23 views

Why must spacecraft reach escape velocity to escape Earth (or any other big object)?

I think I have learned in physics that escape velocity is defined as the speed at which objects going ballistic in the opposite direction of the main gravitational force are able to finally overcome ...
0
votes
0answers
14 views

Baseball innovation [on hold]

I am working on technology for pitchers that will go inside of a baseball and give feedback on the velocity of the baseball, the spin of the ball, the direction of the spin, and the acceleration. I am ...
0
votes
0answers
8 views

A free jet of liquid (incompressible) strikes a wedge as shown in figure below [on hold]

A free jet of liquid (incompressible) strikes a wedge as shown in figure below.
0
votes
0answers
11 views

For a velocity field u(x, t) r r in a fluid of density (x,t) r r , show that [on hold]

For a velocity field u(x, t) r r in a fluid of density (x,t) r r , show that
0
votes
0answers
5 views

Comets in a young star cluster, how are they affected by gas?

As I understand it from looking at some simulations of young star clusters they were held together by a gas that dissipated eventually. The gas is usually represented in models of star clusters as a ...
-1
votes
0answers
8 views

Use conservation of mass and Newton’s second law to obtain pressure coefficient and show that p2 > p1 [on hold]

Use conservation of mass and Newton’s second law to obtain pressure coefficient and show that p2 > p1
0
votes
0answers
8 views

Equivalent Force from Pressure

I am trying to find the force at a certain point of a plate due to some pressure. I have a picture below (terribly drawn, sorry) but basically I have two plates with hinges on one side and the plates ...
1
vote
0answers
18 views

Ricci tensor of direct product of manifolds

Imagine I have a (Lorentzian) manifold with a metric $\left[ {\begin{array}{cc} g_{\mu\nu} &0\\ 0&g_{mn}\\ \end{array} } \right]$ Will the Ricci tensor be also block diagonal ...
2
votes
1answer
11 views

Correlation between large-scale galaxy structure and CMB fluctuations?

During a relatively non-technical astronomy seminar the other day, the speaker displayed the famous WMAP full-sky image as an aid to describing what the CMB is, the scale of its fluctuations, etc. ...
0
votes
1answer
18 views

What is the eastward deflection due to Coriolis force [on hold]

Suppose, an air parcel is at the equator, and it has a northward velocity of 10 m/s. Due to Coriolis force, what is the eastward deflection of the parcel when it reaches 30N. Please show full ...
0
votes
1answer
25 views

Projectile Motion on an inclined plane [on hold]

There are two parallel planes, each inclined to the horizontal at an angle $\alpha$. A particle is projected from a point, midway between the two planes, such that it grazes one of the planes and ...
1
vote
2answers
33 views

Do atoms of a surface excite to reflect the light?

How do surfaces reflect certain colours and absorb the others?
-2
votes
0answers
34 views

Where do I get authenticated information on physics? [on hold]

Sometimes I search for something and I find many answers like this situation: I was searching Google for Who invented the right-hand grip rule? I'll quote what these sites said about that topic: 1 ...
0
votes
1answer
18 views

Centrifugal force for non accelerated motion

If a body is under non-uniform circular motion, will it experience or will there be any impact of centrifugal force on the body upon eliminating the centripetal force?
0
votes
0answers
7 views

2 calculations on absorbed and exposure dose [on hold]

1-A beam of 4.5 Mev neutrons is directed at 0.03 Kg tissue sample. Each Second 1.5×10^6 neutrons strike the sample. If the relative biological effectiveness of these neutrons is 7.0 . WHAT ...
1
vote
1answer
34 views

Send a signal from earth to a planet billion light years away.. instantly [duplicate]

If light was infinitely fast, we could just send a light signal from earth to the planet. But I was wondering, if we made a perfectly non-elastic rope as long as the distance between earth and the ...
2
votes
1answer
43 views

$SU(2)$ gauge symmetry

Take the Lagrangian with one fermion: $$ \mathcal{L} = -\frac{1}{4}F^{\mu\nu}_aF^a_{\mu\nu} + \bar{\psi}(i\gamma^\mu D_\mu - m)\psi$$ where the gauge covariant derivative $D_\mu = ...
1
vote
1answer
15 views

Why do tropical cyclones not tear themselves apart?

A tropical cyclone is the generic term for a hurricane, typhoon, or tropical storm. Tropical cyclones derive their energy from evaporation of water at the ocean surface which ultimately recondenses ...
1
vote
0answers
11 views

2 Nucleon Potential

I am looking at a 2 Nucleon potential of the form $$V(r)=V_0(r)[a+bI_1\cdot I_2]$$ Where a and b are constants. $I_1,I_2$ are isospins. $V_0(r)$ is of the square well form. My goal is to find an ...
0
votes
1answer
21 views

Curvilinear coordinate system around body of revolution

In Boundary-Layer Theory by Schlichting he gives the boundary-layer equations for a body of revolution according to the paper by Boltze$^1$. Unfortunately, this paper is in German. He apparently uses ...
0
votes
4answers
46 views

What happens in a circuit, when the wire and the battery are superconducting. And shorted

When a wire with no resistance is connected to the terminals of an ideal battery, will a current exist in the circuit? If a capacitor is added to the circuit, will it be charged by the battery or will ...
0
votes
2answers
31 views

Joining 2 capacitors in a circuit [on hold]

Consider 2 capacitors having capacitance $C_1$ and $C_2$ charged to potential $V_1$ and $V_2 (V_1>V_2)$. If a circuit was made in which just the 2 capacitors were connected together, would it ...
1
vote
1answer
32 views

What is the difference between mechanical and thermodynamic pressure?

To start with I know thermodynamics deals with processes at equilibrium. Hence the thermodynamic pressure should most likely be the pressure of a fluid at equilibrium. I'm not sure if a fluid flow ...
2
votes
1answer
46 views

Does water turn solid under deep ocean because of high pressure?

I know that we can make water solid with high pressure, so I think water will be solid in the deep ocean? If that is true, the depth of the ocean would be limited because water will become ice? ...
10
votes
2answers
297 views

Why uncertainty principle is not like this?

In Griffiths' QM, he uses two inequalities (here numbered as $(1)$ and $(2)$) to prove the following general uncertainty principle: $$\sigma_A^2 \sigma_B^2\geq\left(\frac{1}{2i}\langle [\hat A ,\hat ...
1
vote
0answers
9 views

Cubic Gaussian Surface For Evaluating Electric Flux

i'm working through some problem sets about Gauss' law and all the examples I have come across so far require the use of a spherical gaussian surface for a point charge, so that it is possible to say ...
2
votes
0answers
45 views

Degenerate perturbation theory applied to topological degeneracy?

Consider a quantum system described by a gapped Hamiltonian $H_0$ with degenerate ground states (GS), adding a perturbation term $V$ to $H_0$, then the low-energy physics can be described by an ...
0
votes
1answer
17 views

Calculating the distance between Detector and Double Slit

I have a little problem that is kind of confusing me at the moment. The following task: Light of the wavelength $\lambda = 500nm$ hits a double slit whose distance is $a = 30\mu m$. Each is $a = ...
0
votes
0answers
19 views

Relative motion setting course of closest approach

Let $r_{P/Q}$ be the position vector of $\overrightarrow P$ relative to vector $\overrightarrow Q$ and $v_{P/Q}$ the velocity vector of $\overrightarrow P$ relative to $\overrightarrow Q$. Suppose ...
3
votes
2answers
590 views

Does it make sense to open one window all the way when the other window is much smaller?

I can't wrap my head around this idea because I don't know much about air flows. Say we have this imaginary apartment with two windows, one of which is two times smaller than the other: Will the ...
0
votes
1answer
37 views

Breakout - physics when ball hits paddle? [on hold]

I'm making Breakout in Java, I've got the paddle and the ball made. The ball has a X and a Y velocity. I've already inverted the ...
0
votes
1answer
34 views

Find pressure of liquids without making contact with it

Is there any way to find the pressure of a liquid inside a closed container without making contact with it? You can make any assumptions, like transparent container or anything, only rule, the ...
0
votes
2answers
23 views

Non-uniform circular motion, computing the angle

There is an object moving in circle, with this law: $$ \alpha = -k^2 \theta $$ With $ \alpha = \frac{ d \omega }{dt} $, and $ \omega= \frac{d \theta}{dt} $, $\theta$ = angle, $k$ positive ...
1
vote
3answers
50 views

Why can colors be mixed? [duplicate]

We can combine colored light, creating other colors, at least in terms of visual perception. But how it the result physically "a different color" - if it is at all? Or is all this not a physical ...
0
votes
1answer
20 views

What is the correct way to take out equivalent capacitance here?

So here I have a capacitor with two plates , one positively charged and one negatively, as shown in the figure. Now the material between them is $k_1$ for thickness d/2 and $k_2$ for the other d/2. ...
0
votes
1answer
25 views

Finding the odd parity bound state wave function for a particle in one dimension

Let a particle of mass $m$ and energy $E$ be moving on the $x$-axis in a potential $V(x)$ given by $$V(x)=\left\{\begin{matrix} -V_{0}, & -a<x<a\\ 0, & otherwise \end{matrix}\right.$$ ...
1
vote
2answers
29 views

Anchor of a boat

hope you can help I've been teaching my kids about pirates and when we were talking about pirate ships this morning I confused myself greatly. When carrying an anchor a pirate ship (or any vessel ...
0
votes
0answers
13 views

Transformers rate equation

Going back to transformers after some years I realize they hide a possible missconception I'm not sure I really understand. It is not easy to find a full derivation of the well known relation ...
1
vote
0answers
27 views

When can I use semiclassical approximation?

I know that I can use semiclassical approximation for path integral (in quantum mechanics) $\int d[q]e^{iA}$ when action $A >>1 $. But how shall I use such condition? For example, assume that I ...
1
vote
0answers
44 views

Heisenberg Uncertainity Principle

If any senior member of the group has access to the book, The Physical Principles of Quantum Theory by W. Heisenberg, then please help me in understanding the first section of chapter 2 where he gives ...
2
votes
3answers
159 views

Ordering of differential operators

If we write something like: $\partial_a X_{\mu} \partial^a X^{\mu}$ Does that mean the first derivative is only applied to the first X? ($\partial_a X_{\mu})( \partial^a X^{\mu}$) Or is the ...
0
votes
2answers
26 views

Velocity required for orbit of satellite

I am very confused about orbital velocity for satellite launched from earth. It is states that: $$ v=\sqrt{\frac{GM}{r}} $$ Some says that it is equal to 8000 m/s and some say 3.1 km/s. Please remove ...
0
votes
1answer
39 views

Lorentz transformation of electromagnetic 4-potential

I'm looking for the exact correspondence between Lorentz transfer four vector and the four vector of scalar and vector potential $A^\mu = (\phi(t,\vec{x}),\vec{A}(t,\vec{x}))^{T}$. Does $ct=A(t), ...
2
votes
1answer
28 views

Higgs mechanism and neutral fields

Consider a Lagrangian $L(\phi,A_{\mu})$ with $\phi$ being some scalar field and $A_{\mu}$ some dynamical U(1) gauge field that minimally couples to $\phi$. Under a global U(1) symmetry the field ...
0
votes
1answer
17 views

Calculate the effective linear attenuation coefficient of a megavoltage multi-energetic beam

Are you aware of a method or source for calculating the effective linear attenuation coefficient,$\mu_\text{eff}$, of a megavoltage multi-energetic beam ? For a mono-energetic beam one could use the ...
0
votes
0answers
43 views

Wave Function Integral I need help conceptually and Mathematically

$$\int_{-\infty}^{\infty}\frac{\partial^2\bar{\psi}}{\partial{x^2}}\frac{\partial\psi}{\partial{x}}~dx.$$ I have read that this is equal to Zero. Only problem is that what I am reading about doesn't ...

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