Applies to questions of primarily educational value - not only questions that arise from actual homework assignments, but any question where it is preferable to guide the asker to the answer rather than giving it away outright. Please READ THE GUIDANCE IN META before asking homework questions.

learn more… | top users | synonyms (1)

0
votes
0answers
184 views

Current Carrying Wire Loop near Current Carrying Long Wire

A rectangular wire loop of (width $a$ and height $b$) carrying clockwise current $I_1$ is a distance $d$ below a horizontal infinitely long wire carrying a current $I_2$ to the right. What is the ...
0
votes
0answers
22 views

Galactic flux given magntiudes

Introduction I have the following data for a galaxy: apparent magnitude in $U,B$ and $V$ Johnson photometric system: $$m_{U}=17.51 \\m_{B}=17.08 \\m_{V}=16.74 $$ The galaxy is such that the ...
0
votes
0answers
83 views

What does “define analytically” mean?

I'm trying to do my homework in physics but here I have found something that I am not understanding. It says: Define analytically the terms that should stationary flow accomplish. I know that ...
0
votes
0answers
103 views

Pressure Rise in Closed Tank with 2 Inputs

Supposing you had a cylindrical closed tank inside the body of a submarine; the top of the tank is at 200m depth. The tank has height 2.5m and internal volume 1.8m^3. A section of pipework is ...
0
votes
0answers
213 views

Angular Frequency about stable equilibrium

So I have the potential energy defined as: $$U(x)=U_0[2(\frac xa)^2-(\frac xa)^4]$$ And I want to find the angular frequency of oscillations about the point of stable equilibrium. I found the point ...
0
votes
0answers
31 views

Uniform distribution of charge on a plane and on a bar: conditions to have no motion of the bar

On the plane z=0 there is a superficial charge distribution such that $\sigma$ is constant. Near to the plane, there is a bar, charged uniform with total charge q. At the extremities the bar has two ...
0
votes
0answers
122 views

Calculating Integrated Precipitable Water using GPS

I'm trying to calculate the Integrated Water Vapor (IWV) using GPS data. I'm following the equations in the following publication: GPS Meteorology: Remote Sensing of Atmospheric Water Vapor ...
0
votes
0answers
60 views

Which pressure to use in the $T~ds$ equation?

Let's say I have an adiabatic, rigid, open container that has an amount of air at some pressure, $P_\text{cv}$, and some temperature, $T_\text{cv}$. I have heated pressurized air coming into the ...
0
votes
0answers
83 views

positron / electron annihilation - where is the invariant?

Electron and a positron are headed towards each other with same kinetic energies - observed from center of mass (COM) system. After the colission two photons are emitted and are headed in opposite ...
0
votes
0answers
53 views

Kaon spontaneously splits into two pions (just need an confirmation)

I just need a confirmation on a problem that I am dealing. In my problem I have a statioary kaon which spontaenously splits into two pions which are headed in different directions. Is it possible to ...
0
votes
0answers
331 views

Scalar field lagrangian in curved spacetime

I am studying inflation theory for a scalar field $\phi$ in curved spacetime. I want to obtain Euler-Lagrange equations for the action: $$ I\left[\phi\right] = \int ...
0
votes
0answers
88 views

Angular momentum contained in E&M fields

I am trying to do this question as a prep for my quals and find my solution too simplistic. I fear I am missing something important. "Iron atoms (atomic mass 56) contain two free electron spins that ...
0
votes
0answers
27 views

How to calculate independent componets of tensor for crystal symmetry?

I have a question as title says. For a formula $j_i = \beta_{ijl} e_j e_l^*$, where $i$, $j$, $k$ are coordinate and $\beta_{ijk}$ is the tensor, if I know the tensor should be satisfied for crystal ...
0
votes
0answers
314 views

Is it possible to solve a 2D relative motion question using components of relative velocity?

This is a question based on concepts of two dimensional motion . Here's how the question is: A plank A is floating in air, gravity has no effect on it (See its coordinates in the figure attached). ...
0
votes
0answers
34 views

Quantum tunelling problem - got a weird imaginary ratio in the end

1. The problem statement, all variables and given/known data Beam of electrons with energy $10eV$ hits the potential step ($8eV$ high and $0.5nm$ wide). How much of the current is transmitted? ...
0
votes
0answers
23 views

What are physical effects that could be employed to emulate this system?

This is a simple system consisting of a tree of numbers such as ((1 2 (3 4)) (2 6) 1 6) and a rule of application, that states that a tree A applied to B is a copy ...
0
votes
0answers
37 views

Finding all marked elements using Grover's algorithm

As part of an assignment I am supposed to design a variant of Grover's algorithm that finds all $t$ marked elements. I guess like most people I'm more familiar with classic computation, so the ...
0
votes
0answers
148 views

Calculating uncertainty $\Delta E$ or $\Delta E_k$ from $\Delta p$

How do we calculate uncertainty in kinetic energy $\Delta E_k$ if we only know that an (a) electron (b) proton is closed in a 1-D box of width $d=10fm$. I first assumed that uncertainty in position ...
0
votes
0answers
75 views

Crystalography - hardest homework problem i have seen so far

The problem statement: We are observing an electron diffraction on a "Ni" crystal. We point the narrow beam of electrons on a crystal which can be rotated so that we are changing the angle ...
0
votes
0answers
81 views

nuclear physics- Energetics and Mechanics of Nuclear Reaction Homework

A sample of $^{24}_{12}\mathrm{Mg}$ is bombarded by a monoenergetic proton. If the resulting nucleus in a $^{24}_{12}\mathrm{Mg}(p,\gamma)$ reaction; $^{24}_{12}\mathrm{Mg}(p,\gamma)$ has its ...
0
votes
0answers
91 views

Question on Binet's equation

Is there a difference in Binet's equation when the force acting on a body is attractive and repulsive? I mean, if the force has a magnitude $F(r)$, is it Binet's equation always ...
0
votes
0answers
187 views

Pair annihilation - how to generaly solve these types of problems?

Simple question regarding pair production: Can a collision of an electron with a positron result in two photons? I have this problem to solve and I doubt this is even possible. Please provide some ...
0
votes
0answers
61 views

How can this formula be analyzed intuitively?

Given $$ \bar{U}_{vib}(T) = R \sum_{\text{n.m.}} \left( \frac{\theta_{vib, n.m.}}{2} \right) + \frac{\theta_{vib, n.m.} e^{-\theta_{vib, n.m.}/T}}{1-e^{-\theta_{vib, n.m.}/T}} $$ where ...
0
votes
0answers
111 views

Taking length/area element when trying to find E.resistance

I am trying to find out which 'element to take' (and why), When trying to find the resistance of some material with non-uniform resistivity $\rho$. I'll give an example: Say we have a co-axial cable ...
0
votes
0answers
182 views

Coupling oscillator

I am currently doing the following problem: Two identical undamped oscillators, A and B, each of mass m and natural (angular) frequency $\omega_0$, are coupled in such a way that the coupling ...
0
votes
0answers
348 views

Collision of 2 particles - calculating the mass and a speed after the collision

Lets say we have a particle of mass $m_1$ which has a kinetic energy $W_{k1}$. This particle collides with another same particle. How can i calculate mass $m_2$ and the speed $v_2$ of the particle ...
0
votes
0answers
36 views

Viscous force in a conductor

I was told that in a conductor there is a dissipative force and if Ohm's Law is valid for a component, the component has to be dissipative. I'm trying to prove it, but I have some problems. I know ...
0
votes
0answers
100 views

Please correct my understanding of Clausius-Clapeyron and latent heat

As I work a problem set, I'm being asked to calculate the latent heat associated with a particular phase transition of $NH_3$ (solid -> liquid, liquid -> gas, solid -> gas). I'm being told to perform ...
0
votes
0answers
55 views

First-order pertubation theory

I'm having some trouble figuring this out, so I was hoping someone could help. I need to show that the first-order pertubation of the ground state energy is not changed by the pertubation $H'$, given ...
0
votes
0answers
437 views

Density of states of a photon gas in volume V and temperature T

I have a question on the density of states for a photon gas: Suppose I have a photon gas in a box of volume $V$ at temperature $T$. If I enumerate the total number of states accessible to the system ...
0
votes
0answers
231 views

How does the volume change affect an adiabatic process?

A gas consisting of rigid diatomic molecules was initially under standard conditions. Then the gas was compressed adiabatically, 5 times the original volume. Find the mean KE of rotating molecules ...
0
votes
0answers
75 views

Question regarding operators and cylindrical coordinates

I have the following problem in my hand: I need to arrive from the Cartesian expression $$x_{j}{\partial_{k}}x_{j}{\partial_{k}}-x_{j}{\partial_{k}}x_{k}{\partial_{j}}$$ to this expression: ...
0
votes
0answers
75 views

Relativistic canonical transformation

What is relativistic canonical transformation? I need every piece of information about it. Does anyone know a reference or an article about relativistic canonical transformation? For example, in ...
0
votes
0answers
226 views

Object on an inclined plane

I was solving a question about inclined planes, and it got me thinking: Imagine a scenario where, an object is on an inclined plane and the inclined plane is on a frictionless surface, and is itself ...
0
votes
0answers
174 views

Determining the length of a Torsional Pendulum

Currently working on this question, however I'm not sure how to solve it. As a pendulum swings in simple harmonic motion at the surface of the Earth, the angle the pendulum makes relative to its ...
0
votes
0answers
79 views

What does this notation mean in terms of quantic numbers, and how to imagine the electrons in this quantic system? (Helium $2^1$ $P$ and $2^3$ $P$)

Helium atom in the $2^1$ $P$ and $2^3$ $P$ excited states Now I'm guessing that 1 electron should be considered in the 1s state, but what about the other? Should I consider the other as simply ...
0
votes
0answers
66 views

Can a magnet spin a small machine?

If you were to build an upright machine that had a rod fitted into a ball bearing at the base and was secured to another rod at the top of the initial rod extending perpendicularly. To which you ...
0
votes
0answers
125 views

Equilibrium of a sphere in a water tank

A rigid sphere of radius $R_S$ made from a material with specific gravity $SG_s$ is completely submerged in a tank of water with radius $R_t$ and initial depth $L$ as shown in the figure The ...
0
votes
0answers
86 views

Finding the coefficients of a spinor

From the Schrödinger equation of a system I'm investigating, where the wave function is a 4-component spinor of coefficients $C_1, C_2, C_3, C_4$, I am able to obtain the expression $\begin{pmatrix} ...
0
votes
0answers
322 views

Equation of motion of charged particle under effect of magnetic field

A charged particle with specific charge q/m diverges from the origin [to the first quadrant] by angle X with x axis and with velocity v. To bring the particle back to the x axis, a magnetic field B is ...
0
votes
0answers
58 views

Switching from an accelerated frame of reference to a locally inertial reference system

Using the equivalence principle, show that the interval for an accelerated observer ($\textbf{g}$ uniform and constant) has the form $$ ds^2|_{\text{first order in ...
0
votes
0answers
154 views

Wave equations for two intervals at Potential step

Lets say we have a potential step as in the picture: In the region I there is a free particle with a wavefunction $\psi_I$ while in the region II the wave function will be $\psi_{II}$. Let me ...
0
votes
0answers
38 views

Is it easier to determine the number of states with raising/lowering operators or using scattering?

A particle is bound by $$V(x) = \begin{cases}\infty,& x <0 \\ \frac{-32\hbar^2}{ma}, & x\le a \\ 0, & x \le a\end{cases}$$ a) how many states are there? i'm attempting ...
0
votes
0answers
1k views

Why a person with a further near point experience a larger magnification with a magnifier

Two people, Micah and Lyra, with different near points are equally close to an object. Both inspect the object through the same magnifier by holding the lens close to the eye. Micah's near ...
0
votes
0answers
282 views

Maximum Shear on a Beam - beam with fixed support on one end and hinge on other end

A beam $\displaystyle 3m$ long with fixed support on one end and hinge on the other end is subjected to a uniform load of $10\ kN/m$. What is the maximum shear of this beam? The solution is this one: ...
0
votes
0answers
275 views

What is the current induced in a straight wire when a magnetic field is turned from on to off?

Consider a straight wire which runs along the y-axis. A B-field exists which is uniform and only in the x-direction: $$\vec{B}=(B(t),0,0)$$ The B-field at time $t_0$ is 'switched off' in ...
0
votes
0answers
399 views

Nuclear reaction: creation of deuterium

A proton p collides with a neutron(at rest) n at relatively low-energies and creates a 'deuterium-core' d: $$p+n->d+\gamma$$ Find the wavelength for the photon as a function of the proton's ...
0
votes
0answers
120 views

Finding final charge distribution on capacitors on grounding

I am trying to solve the following problem on capacitors: Here's the circuit I have to find the total energy loss when all three switches are closed, and subsequent equilibrium attained. I had ...
0
votes
0answers
41 views

How do I minimize the the stress created by fore-aft forces?

My friends and I are designing a bench press spotter. Essentially, when the user needs help lifting the barbell due to muscle fatigue, an arm on each side of the user raises to provide assistance. ...
0
votes
0answers
357 views

Whats the contact area for elastic contact between a cylinder and a plane surface?

I am trying to determine the contact area between a cylinder and a plane surface of two different materials so that the plane lies tangent to the cylinder. There is elastic contact between the two ...