0
votes
3answers
448 views

What is the use (/ meaning) of $F =ma$? [closed]

I have noticed that Euler's formula for force is useful with a couple of natural forces (at distance), like gravity, that can follow a body any length. If you consider the most common occurrences of ...
6
votes
0answers
110 views

Large Hadron Collider 2015 upgrade, what may we discover?

I realise that the initial answer to my question that may come to mind is, "we don't know yet, obviously" But my question is hopefully not opinion based. For example, does this upgrade have a ...
1
vote
1answer
33 views

What physical change has taken place in a solid, say ice, half way through a latent heat temperature verses time experiment?

During the classic high school latent heat experiment a solid such as ice is heated from below the melting point until it is a liquid above the melting point. During this experiment the temperature ...
4
votes
2answers
359 views

Why is the excited state of 116 Indium more stable than ground state?

Why is the excited state of 116 Indium more stable than ground state? Both undergo beta decay, but the ground state has a half-life of 14 seconds, while the excited state has a half-life of 54 ...
1
vote
0answers
38 views

Higher spins elementary particles

Lorentz invariance requirement of theory imposes the absense of interactions between spin 3 and higher spins bosons and arbitrary field (like spin $\frac{1}{2}$ fermions etc) at least in infrared ...
1
vote
2answers
117 views

direction of friction on an object rolling with constant speed

Although there are many questions similar to this, but none of these specifically talk about the situation with constant speed. A wheel is rolling on a horizontal plane (having some friction) ...
1
vote
1answer
70 views

Derivation of an ordinary, Lagrangian/Hamiltonian and action formulation

I am confused as to how the different formulations in physics are derived. In many fields of physics, we usually begin with an ordinary formulation (e.g Newton's Laws in classical mechanics), and ...
1
vote
2answers
239 views

Can change in temperature cause a change in mass of an object?

If a gold bar is heated to say 200 degree Celsius then will it have the same mass at say 10 degree Celsius. Does energy has mass? If so then does this increased 'heat energy' cause an increase in the ...
0
votes
1answer
30 views

Why does an anti-unitary operator have to be both left and right anti-unitary?

I am reading about anti-unitary operators from here anti-linear operators. They have defined an anti-unitary operator $$K: |\psi\rangle \to K|\psi\rangle$$ $$K(\alpha|\psi\rangle+\beta|\phi\rangle) ...
0
votes
0answers
22 views

How does impulse lose energy in rotation?

I have this kind of empirical signal in Electronics where the signal is 1D current measurement (AD current coming from dynamic processes) such that the wire rotates in a big volume of water/mud: ...
0
votes
2answers
91 views

How Statistical Physics?

It's a common fact that in physics, we use statistics (or maybe probabilities ) to describe the behaviour of a system. It was from the statistical analysis of a system where quantum statistics arose ...
8
votes
2answers
6k views

What is the difference between a “model” and a “theory”?

In my past questions I have used the terms "model" and "theory" interchangeably. So we have statements along the lines of The Standard Model is our best theory of particle physics but I have also ...
0
votes
1answer
47 views

Impact on car without energy dissipation

This must be a relative simple question, but the answer I am obtaining doesn't appear to be logical. Say a vehicle has a velocity of 15 m/s and an effective mass of 1000 kg including occupants. 1) ...
-1
votes
3answers
118 views

Does it make sense to model the Universe from an outside perspective? [closed]

I was reading some questions and answers about black holes and whether matter can actually pass through the apparent horizon, in particular this one: How can anything ever fall into a black hole as ...
4
votes
1answer
86 views

What, if anything, makes primary colours distinct?

I've recently become interested in the primary colours; red, green and blue. In my capacity as a computer programmer I'm well aware of how these colours are used practically, and of how varying ...
1
vote
0answers
53 views

Alternative ways of calculating the principal moment of inertia

Let's say I am given 2x2 masses ($m$ and $m'$ have the same mass, just different coordinates): $m_1: (-a,b,0)$ $m_1':(a,-b,0)$ $m_2: (a,b,0)$ $m_2': (-a,-b,0)$ Due to symmetry the center of mass ...
1
vote
0answers
32 views

Magnetic forces [closed]

Can we generate magnetic field forces for pushing or pulling devices? How much weight can be pulled by electromagnetic field?
0
votes
0answers
62 views

Sphere of electric charge revisited

I am thinking about a sphere of homogeneous charge distribution (see Electric field due to a solid sphere of charge, for example). Here we use a Gaussian surface (blue area) to find the electric ...
8
votes
3answers
771 views

Is it possible to produce gravitational waves artificially?

Why don't they make a ball with irregularities, say the size of a tennis ball, then spin it very rapidly, so it would produce gravitational waves like a spinning star with irregularities on it? Is ...
0
votes
1answer
44 views

How are anti-unitary operators applied?

I was reading about anti-unitary operators from Wikipedia. They give an example of an anti-unitary operator: were $K$ is complex conjugate operation. $\sigma_y$ is defined with respect to two ...
1
vote
0answers
106 views

What does conservation of strangeness imply for the nature of interaction?

If the conservation of strangeness holds for a decay, then the possible interactions are Strong, Electromagnetic and Weak. But how does one determine which one is it, out of the three?
1
vote
3answers
87 views

How can Ac be listed as a single voltage

How can AC be listed as a single voltage (e.g 240V AC) when it constantly varies and what does this have to do with RMS Voltage.
1
vote
1answer
86 views

Quantum mechanics prediction for Bremsstrahlung?

Does quantum mechanics predict the Bremsstrahlung Phenomena? I know it is predicted by classical mechanics through Maxwell's equations, but does QM predict this phenomena and how so?
1
vote
1answer
100 views

Order of index in Lorentz transform

I am reading Schwartz's "QFT and the standard model". On pg 13 he gives the Lorentz transform of a rotation around the x-axis: $ \left( \begin{array}{cccc} 1 & 0 & 0 & 0 \\ 0 & 1 ...
0
votes
2answers
125 views

Is it possible to apply Newton's equation of gravitation to attractive force between the moon and the ocean? [closed]

Someone was asking me how much force is acting on the waves when the moon is closest to the earth. Of course the first thing I tried to do is apply Newton's equation for universal gravitation $$F = G ...
0
votes
0answers
47 views

Understanding Quantum point contact

Am I correct in saying that quantum contact is : for a quantum heterostructure, by applying a voltage between two needle shaped split gate, it would deplete the electrons beneath it, therefore ...
70
votes
6answers
4k views

Thought experiment - would you notice if you fell into a black hole?

I've heard many scientists, when giving interviews and the like, state that if one were falling into a black hole massive enough that the tidal forces at the event horizon weren't too extreme, that ...
1
vote
2answers
214 views

Summation notation for Kronecker delta

I'm having some problems on notation for indices: I've found in Goldstein, 3rd edition, that the Kronecker delta satisfies the following property: $$\delta_{ij}\delta_{ik}=\delta_{jk}$$ But ...
0
votes
0answers
70 views

Double-slit experiment, dielectric material containing the two parallel slits

This is concerning the double-slit experiment. This is concerning the material containing the two parallel slits. Are there experiments where the material containing the two parallel slits -- is ...
0
votes
4answers
245 views

Why do our ears pop?

Have you ever been on a train going through a tunnel or plane and your ears pop?I was wondering why this happens and I know it relates to pressure but don't know exactly the reason
2
votes
1answer
82 views

Relative Velocity Help

I am struggling with relative velocity and so decided to do some extra problems in my textbook. I have 2 problems that seem to contradict, and its annoying things like this that throws me off, leaving ...
0
votes
3answers
94 views

Why is $x=C\cos(\omega t)$ the solution of $m\frac{d^2 x}{dt^2}+kx=F_o\cos(\omega t)$ though lacking two arbitrary constants?

I was studying undamped oscillator with harmonic driving force at the steady-state condition. It can be expressed in the form of differential equation as:$$m\dfrac{d^2 x}{dt^2}+kx=F_o\cos(\omega t).$$ ...
0
votes
0answers
65 views

How to properly implement Huygen's integral?

I'm really confused by what's happening ... I'm trying to propagate a beam some distance and compare initial and final intensities. Lets say the initial electric field is just cos(200x). I then used ...
-1
votes
2answers
74 views

Does special relativity happen in reverse when you freeze?

As you travel faster and faster you experience time at a slower rate, so if you travel slower and slower you should experience it at a faster rate right? My thinking is that even if you are ...
1
vote
2answers
207 views

Incompressible Navier-Stokes pressure solve in simulations

I am a complete newcomer when it comes to fluid simulations. I'm currently working through some tutorials to understand the idea of of the discretized Navier-Stokes equations for numerical ...
0
votes
0answers
53 views

Is there any explanation for these objects apparently traveling faster than light? [duplicate]

This is from a documentary on the science channel: https://www.youtube.com/watch?v=RaELad94KZs
3
votes
1answer
95 views

How fast do you have to be traveling in order to travel one light year in one year due to relativistic effects?

My apologies if my understanding is incorrect, but I believe that as you approach relativistic speeds you experience time dilation as compared to an outside observer. So taking into account this ...
2
votes
1answer
62 views

What exactly is conservative vector field?

I'm studying calculus, but since the example involved a physical concept. I will ask here: This is how it goes: This means that in a conservative force field, the amount of work required to ...
0
votes
1answer
143 views

Convert Temperature into Speed/Kinetic Energy

If the temperature of an object is simply a measurement of the average kinetic energy of the molecules within it; is it possible to convert the temperature of an object, given it's volume, into either ...
0
votes
0answers
22 views

What is the entropy of strong and weak nuclear forces? [duplicate]

Can we determine the entropy of strong and weak nuclear forces? If so, what will be the formula to determine the strong and weak force entropy? Thank you :)
1
vote
1answer
66 views

Does GR put a theoretical lower limit on the radius of a black hole event horizon?

Within GR theory, without going to the extreme r/0 as a radius, (but approaching that as an asymptotic case), is there any theoretical limit as to how small the event horizon of a rotating and/or ...
0
votes
0answers
56 views

Can you explain this “Theory of Everything”? [duplicate]

I recently come across with an amazing equation of Theory of Everything; I wonder if TOE has been formulated (???) I found this equation on a website, check it out ...
-1
votes
2answers
67 views

What are the consequences of a non-computable universe?

I have seen that is is debated if the universe is digital, computable or non-computable. what specific consequence could this have in the format of the laws of physics? Or would that mean that we will ...
3
votes
0answers
92 views

What are possible explanations for the permeability of balloon rubber, PET plastic and other synthetic materials for carbon dioxide?

Balloons are definitely not gas-tight. Carbon dioxide just leak by the rubber away. A balloon is filled with carbon dioxide. Knot in it. And play. Shrinkage. After an hour or two the carbon dioxide ...
3
votes
0answers
119 views

Is there a relationship between force and entropy?

Is there any relation between force and entropy? If any, I would like to know what the equation of this relation will be. What is the entropy of strong and weak nuclear force? Can we determine it? If ...
0
votes
2answers
54 views

Change of magnetic flux on size of magnetic field and area

Consider a solenoid with 50 turns. Each turn gives has an area $A$. When the power is switched on, each turn produces a magnetic field of 1 Tesla. What is the total change in magnetic flux when the ...
1
vote
0answers
25 views

For an intrinsic semiconductor, why is fermi level half-way? [duplicate]

Why is the fermi level half-way between the conduction band and valence band?
1
vote
1answer
91 views

Do particles have spin because there exist spinor representations for the Lorentz group?

I am reading Peskin and Schroeder's An introduction to field theory. They first describe the spinor representation of the Lorentz group, and then they mention the fact that different particles have ...
0
votes
0answers
91 views

What is the cause of the time-varying electric and magnetic near-fields around a wire with a 60Hz AC current?

I know that it's the accelerating electrons in an AC current that are the cause of far field effects. But, what about the reactive near field close to a wire that has a 60Hz AC current? What is the ...
1
vote
0answers
135 views

Ishibashi states and Cardy states in CFT

What are the Ishibashi states and Cardy states in CFTs? I am familiar with conformal field theory language. It would be great if someone can discuss about the basic idea of these states and their ...

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