0
votes
1answer
22 views

When water turns to steam at 100 degrees Celsius why does both the internal and potential energy increase?

I thought during this transition only the potential energy increases as energy is used to weaken the van Der Waal forces between the molecules. And that the internal energy is only dependent on the ...
-3
votes
0answers
34 views

can there exist an imaginary pivot in mechanics? [on hold]

Can there exist an imaginary pivot in mechanics. for example there is a mass attached to a rod of length l? so the pendulum can move in a fixed plane.now my question is that can there be a pivot ...
1
vote
2answers
78 views

Horizontal rolling without slipping

I'm trying to find the friction coefficient that makes the body roll without slipping but I just can't reach a value. The force is applied on a small central disk of radius $r=0,03\, m$ and mass $m=0,...
2
votes
2answers
18 views

Why is the damping force acting on an oscillating system opposite in direction to velocity and not acceleration?

So far I know that the damping force is a frictional force that opposes motion and so it acts in the opposite direction to velocity . Bit why can't the same be said for acceleration doesn't the ...
-4
votes
0answers
23 views

How to calculate temperature of the universe from cosmic microwave background radiation? [on hold]

Two scientists detected the cosmic microwave background radiation at a frequency of 160 GHz. What is the temperature of the universe? So I used the following two equations. peak wavelength x ...
0
votes
0answers
17 views

Landau Diamagnetism and Pauli paramagnetism

In the conventional definition of Landau's diamagnetism we ignore the effect of spin-electron coupling and vice versa for the derivation of Pauli's paramagnetism. I want to know what would happen if ...
0
votes
1answer
45 views

What is the relationship between Maxwell-Boltzmann statistics, Boltzmann distribution and Maxwell-Boltzmann distribution? [on hold]

I have recently been studying some statistical thermodynamics and I am currently trying to understand all the different concepts of the course. I was wondering about differences between MB statistics, ...
1
vote
1answer
16 views

Frictional torque=? [on hold]

A uniform, hollow, cylindrical spool has inside radius $R/2$, outside radius $ R$, and mass $M $ (see figure below). It is mounted so that it rotates on a mass less horizontal axle. A mass m is ...
4
votes
1answer
60 views

What is rotational potential energy?

I don't understand the concept of rotational potential energy. During linear motion, when a force is applied, the work it does gets converted to kinetic energy and there is no change in the ...
4
votes
1answer
47 views

An ideal black - body at room temperature is thrown into a furnace. It is observed that?

An ideal black - body at room temperature is thrown into a furnace. It is observed that? (A) initially it is the darkest body and at later times the brightest. (B) it is the darkest body at all ...
1
vote
1answer
31 views

How can one determine whether two given Hamiltonians are supersymmetric partners?

Given two Hamiltonians in a general form of second order differential equations, how do I find out if they are SUSY partners or not? Given the factorisation of a Hamiltonian in the form of $a^\dagger ...
-3
votes
0answers
30 views

Force applied to the rod [on hold]

How much force is applied to the other end of the rod the moment you cut the string? (g=10m/s^2)
0
votes
1answer
29 views

Situations in which there is path difference interference or formation of standing waves [on hold]

I came up with a doubt about standing waves and path difference in general. Consider these two different cases as examples. If I have a rope fixed at one end and I make the free end oscillating, I ...
-1
votes
0answers
27 views

Sturm Liouville potential

How to determine the potential function of a Hamiltonian, given by a general second order differential equation using the Sturm-Liouville theory? Of course, any other approach is also appreciated. ...
0
votes
0answers
26 views

Balancing a Quantum mechanical pencil [duplicate]

I have tried to solve the question given in Sakurai quantum mechanics book about what is the maximum time you can balance a pencil on its tip using the uncertainty principle. Classical pencil is in ...
-3
votes
0answers
26 views

Transformer primary and secondary coil current problem [on hold]

A step up transformer has 300 turns on its primary coil and 90,000 turns on its secondary coil. The potential difference of the generator to which the primary circuit is attached if 60 V. The ...
-3
votes
0answers
20 views

Loop the loop question: A marble of mass $m$ and radius $r$ rolls along the looped track in the image [on hold]

A marble of mass m and radius r rolls along the looped track in the image: What is the minimum value of H if the marble is to reach the highest point of the loop without leaving the track?
2
votes
0answers
19 views

Multi-Cut Matrix Models

I have a question pertaining specifically to a one-matrix model with a multi-cut solution. The standard procedure is to take a polynomial superpotential $W(x)$. In the classical limit (analogous to $...
-3
votes
3answers
47 views

Average speed without given distance [on hold]

Here is the problem where the speed is given but not the distance and need to find the average speed.
1
vote
1answer
31 views

How is the amount of radiation calculated from a decay?

Lets say you have some unstable isotope which decays via beta decay. For example, lets say you want to calculate the amount of beta radiation that is emitted from the decay of $^{87}\textrm{Kr}\to ^{...
1
vote
1answer
27 views

Why is the Vacuum Expectation Value measured in GeV?

As I understood, the Higgs field has a non-zero vacuum expectation value (vev) on zero energy. For example, in the case of the non-quantized electric field, it would be measured in $\dfrac{J}{C}$, i....
-5
votes
1answer
41 views

Communication via teleportation/entanglement (FTL communication)

I know this has been asked many times, but I have a hard time "crystallising" it in my mind. First: let's say we teleport a DVD (with quantum teleportation). Isn't this FTL communication? Second: ...
1
vote
0answers
36 views

How to plot numerically the wave functions according to the Hamiltonian?

It is often difficult to analytically solve the Schrodinger equation, and so we need to obtain a solution numerically. An example plot is shown below. Here, the wave functions for a three junction ...
5
votes
2answers
78 views

Uncertainty Relations, Conjugate Quantities, and Fourier Transforms

I've heard from a lot of people that the reason momentum and position have an uncertainty relation is because of the Fourier Transform. But is this in any way the case? If it were I would expect all ...
2
votes
0answers
37 views

Does Feynman parametrization commute with derivative?

Let $I = \int \frac{d^4k}{(2\pi)^4} \frac{(p+k)\cdot\gamma}{(p+k)^2-m^2+i\epsilon} \frac{1}{k^2+i\epsilon}$ I would like to do two operations on the integral, namely Feynman parametrization and $\...
0
votes
1answer
29 views

What would be the masses of the elemental particles if the Higgs field had a different value?

Afaik there is some function, for example, for the mass of the electron $m_e(\phi_1, \phi_2, \phi_3, \phi_4)= ...$, and similarly to the other elemental particles. What is this function?
2
votes
1answer
68 views

Gravitational force between Earth and Sun is decreasing

According to one of the most famous equations in physics, i.e. $E=mc^2$, the mass of the Sun is decreasing as it emits energy. So there must be some kind of disturbance in planetary orbits, and if ...
1
vote
0answers
24 views

Functional variation of potential in integral form

I am trying to vary the following action, $$ S=\int_{t_0}^{t_1} \text{d}t\,(v^\mu v^\nu g_{\mu\nu} + V(t)) =\int_{t_0}^{t_1}\text{d}t\,(v^\mu v^\nu g_{\mu\nu} + \int_{t_0}^t\text{d}s T_\mu v^\mu) $$ ...
0
votes
1answer
44 views

Why do Newton's laws hold in a normal and tangential coordinate system?

In my book it says: 'When applying the equations of motions, it is important that the acceleration of a particle be measured with respect to a reference frame that is either fixed or translates with ...
9
votes
3answers
559 views

General relativity vs graviton discovery

Will the discovery of the graviton lead to the redundancy of general relativity even though it has been so well established. If not, will it mean that gravity will have two separate theories that ...
-2
votes
0answers
23 views

Inversed square law (destroying a hypothetical solar system) [on hold]

Here is my question, say it was possible to have enough antimatter as the explosive of choice to achieve such a feat, and that a black hole isn't formed the magnitude of energy at the origin. How much ...
0
votes
1answer
28 views

What is the tension on the horizontal rope in this conical pendulum setup? [on hold]

A rope is attached to the top of a straight pole. A person of 890N and a seat of 201 N are attached to the end of this rope. The person rotates 37.4 revolutions/min in the horizontal plane while the ...
0
votes
1answer
24 views

Potential step and tunnelling

Imagine a particle with energy $E$ heading towards a potential step with height $V_0$ where $E<V_0$. The particle's wave function is oscillatory before the boundary and exponentially decaying in ...
0
votes
1answer
15 views

Wear rate with sliding speed

I read so many research studying the effects of sliding speed on wear using pin on ring testing machine all of papers said: when the sliding speed increase the wear rate will increase because the true ...
2
votes
1answer
37 views

Propulsion system

Can a propulsion system be made by facing two air ionizers towards each other, accelerating the ions with fans, and having them repel each other? Would the force generated be greater than just ...
0
votes
1answer
34 views

Direction of travel in universe

When observe the universe we see that galaxies are much closer than they are at this very moment because of the time it takes for the light to reach us. However do we see this phenomenon in every ...
5
votes
1answer
47 views

Eigenvalues of spherical harmonics in $d$ dimensions

I'm working on the Schrodinger equation for a hydrogen atom in a $d$-dimensional space, so I'm interested in the possible eigenvalues of the angular momentum part of the $d$-dimensional Laplace ...
0
votes
1answer
19 views

Charge density on two hemispheres, enclosing a conducting sphere [on hold]

Two uniformly charged non conducting hemispherical shells each having uniform charge density $\sigma$ and radius $R$ form a complete sphere (not stuck together) and surround a concentric spherical ...
0
votes
2answers
37 views

Is uniqueness a fundamental property of nature? [on hold]

The Laws of nature are universally applicable and at every point in force. Together they shape our universe but are all "shapes" unique? For example, is it possible that there is a second identical ...
0
votes
0answers
14 views

triboelectric effect at a liquid-liquid boundary?

In reading up on the triboelectric effect, most experiments deal with solid-solid interfaces. I've found some studies regarding solid-liquid boundaries, and even some engineering manuals outlining the ...
1
vote
1answer
21 views

What is the refractive index for partially ionized plasma plasma (mixture of electrons ions and atoms)?

I asked a question earlier, why ions are not included in refractive index of plasma . What I do not understand is how a refractive index of plasma can be formed mathematically that is just partially ...
1
vote
2answers
42 views

How well-defined is the infinite-sheet-of-mass computation?

When computing the gravitational force from an infinite plane (or the electrical field from an infinite sheet of charge), it is standard to begin by making a symmetry argument to say that the ...
2
votes
2answers
62 views

Projection of a tensor

Consider the following tensor (abstract index notation, e.g. Wald's) $B_{ab}$ and timelike vector field $X^{a}$ such that $X^aX_a=-1$ and \begin{equation} B_{ab}=\nabla_bX_a \end{equation} Then one ...
0
votes
0answers
44 views

Why do we integrate in the following derivation? [on hold]

Electric potential due to a point charge. Let a point O have charge $q$ at a distance $x$ from point A and at a distance $r$ from point P ($r<x$). Suppose a test charge $q_1$ is placed at A force ...
0
votes
0answers
26 views

Can we see interference if move screen? [on hold]

In interference using electrons in double slit experiment, we cannot use light source, as it disturbs apparatus. But, can't we simply move screen towards and away from screen, to know where they ...
-3
votes
0answers
18 views

Uncertainty principle-QM [duplicate]

I some trouble understanding the uncertainty principle. I understand most of the math derivation but not the physics. Is there any intuitive explanation of this idea, and why is the uncertanty does ...
2
votes
0answers
67 views

(1+1)-General Relativity

Goodevening everyone, my question is: What is the interest of studying the (1+1)dimension General Relativity? Can you explain please? Thank's in advance!

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