# Tagged Questions

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.

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### Thermodynamic equilibrium- mixing of gases

What is the final temperature and pressure after removing diaphragm of a cylinder which divides the cylinder into two equal components each of volume $0.1\,m^3$ and each component contains air at ...
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### Joules To Move A Kilogram In Space [on hold]

If roughly ten joules lifts one kg on earth one meter, how many in space? Meter / joule/kilogram Kilogram/meter/joule
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### What will be the time taken by a stone to reach the ground if it is thrown with velocity $v$? [on hold]

I was studying from my reference book and I got this question. I tried solving it by finding the total distance n average velocity but it didn't work please help me out.
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### Finding equation for acceleration using mass1, mass2, gravity, theta, and Mu [on hold]

So, the only question I could not solve in this chapter for AP Physics, and I really want to understand it. We have a situation like this: There is a box sitting on an incline. We are trying to ...
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### Which textbooks contain info on Bessel functions & their use as basis functions?

As an exercise my research mentor assigned me to solve the following set of equations for the constants $a$, $b$, and $c$ at the bottom. The function $f(r)$ should be a basis function for a ...
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### The problem in Sredniki's textbook: How do I calculate loop corrections for $\phi\phi\to\phi\phi$ with this Lagrangian?

The problem in Sredniki's textbook 10.5 : For a free scalar field $\psi$, the Lagrangian is $$\cal{L}= -\frac{1}{2}\partial^\mu\psi\partial_\mu\psi-\frac{1}{2}m^2\psi^2$$ Here we use the metric ...
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### What does y with a line over it represent?

I've been asked to complete this chart and have never come across this symbol before, nor can I find anything about it on google: What does the y with the line over it represent? And also, does the ...
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### Sturm Liouville Problems [migrated]

I'm currently having a class at university that discusses Sturm Liouville Problems. We have to solve a few problems one of which I can't seem to solve. We use Advanced Engineering Mathematics by Erwin ...
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### Doppler shift for a uniformly accelerating observer

This was given in textbook as an example. An observer on a spaceship with a four velocity $u$ is approaching from $x = +\infty$ a star at rest in the reference frame $S$ while undergoing constant ...
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### Is a given charge density a surface charge density or volume charge density?

The exact question goes like this: In a certain electronic tube, electrons are emitted from a hot plane metal surface, and collected by a plane metal plane parallel to the emitter, at a distance ...
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### Uncertainty in position and kinetic energy

How do you find the uncertainties for $x$ and $K$? Knowing that the general uncertainties = $$\sigma_A \sigma_B \geq 1/2\int \psi ^*[\hat A,\hat B] \psi dx\,$$ I figured out the commutator, for ...
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### Change of kinetic energy in a two particle collision

A problem I am working on proceeds as follows: A billiard ball of mass $M$ is initially at rest on a horizontal frictionless table. Another ball of mass $m < M$ and velocity $\mathbf{v}$ in ...
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### What causes a spacecraft entering the atmosphere to catch fire? [on hold]

What causes a spacecraft entering the atmosphere to catch fire? A) surface tension of air B) viscosity of air C) high temperature of upper atmosphere D) greater proportion of ...
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### Kinematics/ Projectile Motion Lab [on hold]

This is a question from a projectile motion experiment. Using kinematics you will be asked to calculate the initial velocity of the projectile by measuring its vertical drop h, and the horizontal ...
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### Normal modes of two parallel $LC$ oscillators coupled via mutual inductance

Consider the circuit shown below. The two LC circuits are arranged in such a way that their mutual inductance M results in a coupling between the currents flowing in the two circuits. Find the ...
582 views

### Prove a dielectric with infinite dielectric constant behaves as a conductor for static fields

I read the following problem: Prove that a dielectric medium for which $\varepsilon \to \infty$ behaves as a perfect conductor in the presence of static electric fields. So, the easy part is that the ...
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### To find angular speed of a rotating body [duplicate]

A body moving with uniform angular acceleration covers 100 pi (rad)in first 5 s. Its angular speed at the end of 5 s (in rad/s) is?? My ans is 40 pi, but according to the answer given in my book ...
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### To find angular speed of a rotating object [on hold]

A body moving with uniform angular acceleration covers 100 pi (rad)in first 5 s.its ang speed at the end of 5 s (in rad/s)is??
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### speed of muons relative to Earth [on hold]

A certain muon detector counts 600 muouns / h at an altitude of 1900m and 380 / h at sea level. Given that the muon half-life at rest is 1.5 × ( 10^-6)s, determine the speed of the muons relative to ...
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### When two objects roll down an incline, does the velocity increase?

I know the basics of rotational motion but this question just confused everything: The answer to the question is A. But why? My problems: If first, I treated both the disks as two particles, ...
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### Image charge method to find electric field [on hold]

The following is a question from my tutorial on boundary value problems and image charge method- A point charge +q is placed at (0, 0, d) above a grounded infinite conducting plane defined by z = 0. ...
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### Vectors in three dimensions [on hold]

A plane travels 40 degrees east of north from the Heliport travelling horizontally distance of 2km while reaching an altitude of 2500m and turns travels horizontally another 3km and loosing 1500m in ...
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### Looking for a simple proof of symmetry of linear susceptibility tensor

Getting a diagonal susceptibility tensor: Define the linear susceptibility tensor as $\chi_{ij}$: $P_i = \epsilon_0\chi_{ij}E_j$, using standard notation for the electric field and the polarization. ...
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### Kinematics - Projectile motion down an inclined plane

The inclined plane has angle A over the horizontal. A projectile is thrown down the inclined plane at angle B relative to the incline at velocity V. What is the time taken, range, and max ...
334 views

### Spring system - 3 DoF system and its properties while changing stiffness

I was given the attached 3 degree of freedom spring system with the purpose of analyzing it. I came up with the following equation of motion and then I ran Matlab to calculate the corresponding ...
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### Conceptual question on helmholtz equation

Given the homogeneous Helmholtz Equation $[\triangledown ^2 + \kappa^2] E= 0$, I understand $\kappa$ represents the wavenumber $\omega_0 / c$. In light of this, what physical meaning can be taken from ...