Use this for questions relating to the proper use of physics terminology or nomenclature.

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38 views

Semantics: alternative word for long-ranged interaction? [closed]

I am working on wording for a report. I need to a word to describe long ranged interaction that is constant in strength. But I am aware that people sometimes use 'long-ranged' to mean decaying ...
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1answer
91 views

Difference between harmonic oscillator & coupled oscillators

Coupling, according to wiki, is the condition of two systems when they interact with each other. Now, I came across the terms harmonic oscillator and coupled oscillators. Now,what is the difference ...
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39 views

What is “Lifetime Intensity” in photoluminescence?

I'm reading an article "Surface plasmon enhanced Förster resonance energy transfer between the CdTe quantum dots". Link The reasearchers are writing about increase in "lifetime intensity" and even ...
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1answer
120 views

Simple explanation of Coherent integration radar

I have a physics background, and I'm reading some physics data analysis papers where they keep throwing around the term coherent integration. I've done the google search, but the best answer I could ...
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1answer
157 views

Does graphene have a honeycomb lattice?

In my grand ignorance I would state that graphene has a honeycomb lattice. Some tend to agree with me and some others do not. I'm curious to know what members of the SE community think is the right ...
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1answer
42 views

Why is a “Semi-leptonic” Decay Mode called so?

Why is a semileptonic decay mode called so? I mean, if there is one lepton amongst the decay products, it should be leptonic, right? If there are two, that should be called bi-leptonic or something ...
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2answers
237 views

How to understand whether potential energy increases or decreases?

I am confused by how to deal with the negative sign in the equation $U=-GMm/r^2$ in the following problem: If the distance between two masses is tripled, then the magnitude of the gravitational ...
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1answer
58 views

Friedmann equations question

Friedmann equations for critical density is: $$\rho_c = \frac{3H^2}{8\pi G}$$ Is there any other way to write this equation? For example: $$\rho_c = \frac{3}{8\pi GH^2}$$ I saw the above form on ...
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163 views

Name of battery voltage when load connected/disconnected

If I had a 3V battery, and when no load connected it reads 3.2V, and with a load 2.8V (just a hypothetical example), what is the name for these two terms, with a load or no load? I know the voltage ...
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1answer
601 views

Is there a name for a substance that is a gas at room temperature?

Is there a name for a substance that is a gas at room temperature, such as Hydrogen, Helium, Neon, Argon, Krypton, Xenon, Chlorine, Fluorine, Bromine, Nitrogen, and Oxygen. I am writing a paper where ...
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2answers
79 views

Should theory be the appropriate term? [duplicate]

Should theory be the appropriate term? I mean, for example, because of the quantum field theory we have been able to find the subatomic particles that it theorized and make the Standard Model. Why ...
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797 views

A basic question: what is accelerating voltage? [closed]

Or would it be acceleration voltage? Acceleration sounds like it makes more sense, but my paper says accelerating. What are possible ways you could go about calculating it?
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353 views

Equilibrium - uniform circular motion

Maybe this is a bit of a silly question, but let us pretend we have a pendulum in a ideal universe with no friction, drag, or anomalous forces there to affect it. Additionally, our pendulum is ...
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1answer
142 views

Can the phrase “Terminal Velocity” be used to describe non-gravity situations?

According to Wikipedia: [Terminal Velocity] is the velocity of the object when the sum of the drag force (Fd) and buoyancy equals the downward force of gravity (FG) acting on the object. Since ...
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1answer
245 views

Proper name for a thermodynamic process with constant internal energy $U$

Back in the day I learned that a few special thermodynamical processes have special names. For example, if one keeps $P$ constant, the process is called isobaric, if one keeps $T, V$ or $S$ ...
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1answer
33 views

What are degenerate transversal oscillation modes?

This is just a question about terminology that is used in the beginning of a chapter about phonons. In a simple cubic crystal, we can consider elastic oscillations in f.i. the [100] direction. In ...
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1answer
47 views

Is there a term for the argument of the sine function outside of geometry?

Are there similar terms in other areas for the idea the "angle" conveys in geometry? I find that functions for abstract things such as pressure, electrical currents (nothing geometric there) on AC ...
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1answer
156 views

Magnitude of a photon?

I encountered the following sentence in my textbook, which I don't quite understand, and after an unfruitful google search, I still can't figure out what they mean by magnitude in this context: ...
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1answer
123 views

What is a long-tailed distribution for physicists?

What is the most common definition of long tailed distribution for physicists? I am looking for definition and examples. Examples should have arguments why the distribution is or is not long tailed. ...
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1answer
162 views

What's the difference between these two formulas and how are these called?

I just want to know the differences between these two formulas: $h = h_0 + v_0 t ± \frac{1}{2} g t^2$ and $y = y_0 + v_{0y} t + \frac{1}{2} g t^2$ Also, how are these called in English?
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364 views

What is the reference spectrum?

What is the reference spectrum? I need to know how to calculate the reference spectrum of a wavelength 500nm.
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385 views

What is the pause called at the apex of an object's trajectory?

My apologies for such a basic question--I am a musician, not a physicist. But I cannot anywhere find the word, if one exists, that describes that elegant pause of an object such as a ball, thrown ...
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3answers
17k views

Difference b/w Kinetics & Kinematics w/concrete example

(I know whether I understand this or not doesn't matter much to my work & study but am just curious.) I still can't differentiate in my head kinetics and kinematics (similar thread is found but ...
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3answers
276 views

Is $f=ma$ an identity?

In his The Principles of Natural Knowledge, Alfred North Whitehead writes that famous $f=ma$ is an identity: It has been popular to define force as the product of mass and acceleration. The ...
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1answer
349 views

What's the difference between “measurement method” and “measurement procedure”? [closed]

The ISO VIM defines them as: measurement method: generic description of a logical organization of operations used in a measurement. measurement procedure: detailed description of a ...
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32 views

Does “$\mathbf r[~t~]$” correctly denote the trajectory of a point particle wrt. a reference system w/o having to decide on a particular origin? [on hold]

Consider a specific geometric reference system, e.g. a specific inertial frame(1): the suitable set of point particles $\mathcal S := \{ H, J, K, ..., O, P, Q, ... \}$; and consider one other point ...
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21 views

Measurement of drag (?) tension between two surfaces

I want to know if there are (reasonably inexpensive) devices to measure the tension between two surfaces. Beware of my terminology: the first help I need is to actually formulate my question ...
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15 views

Radial excitation and orbital-angular momentum excitation

Sorry. Just want to make sure, but what does radial excitation and orbital-angular excitation mean in the context of bound states? Just higher $n$ and $\ell$ quantum number?
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2answers
28 views

Is net work and total work same?

According to my text book Total Work = Delta Kinetic Energy = KEf - KEi But then work is defined to be dot product of Force (vector) and Displacement (vector). Also to my knowledge work is ...
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1answer
40 views

Superscript on density matrix

I have been asked in homework to solve the optical bloch equation for the initial condition of $\rho_{22}=0,\rho_{12}=0$. Professor gave a hint of the general equation and let us carry it from here. ...
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44 views

What is primitive divergence?

As in the title, what is primitive divergence? How is it distinguished from normal divergence? As a followup, what is a primitive divergent graph in a theory? Some simple examples?
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0answers
17 views

Is there a name for the squared refractive index?

In studying wave propagation through multilayers, the squared refractive index $n^2$ is a more pertinent parameter than $n$ itself. Is there a received name for $n^2$? Of course, as long as there is ...
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29 views

What do physicists mean with “classical critical behaviour”?

What do physicists mean with "classical critical behaviour"? As far as I am concerned it should be "power law behaviour" of some quantity close to the critical point but I ask here to be sure.
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67 views

Second law of thermodynamics (in terms of entropy)

Is the second law of thermodynamics (in terms of entropy) for closed systems or isolated systems? I thought it must be valid for isolated systems, such as the Universe. But the book Fundamentals of ...
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20 views

What exactly is meant by “locating points in spacetime”, in the RT?

In this (presently quite popular) answer to another recent question of mine concerning foundations of the (Einstein's) theory of relativity, it is asserted that "Any observer can construct a ...
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52 views

What is the difference between mass defect and mass deficit?

Is there any difference between the mass defect and the mass deficit? I have read that the mass defect of a nuclide is never negative and have also been told that the mass defect is the same as the ...
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1answer
16 views

What are pressure threshold patches called in professional terminology?

I am making a small combustion chamber, and need to measure the pressure when a combustion occurs. This is a hobby project, so I don't have enough money to buy a dP cell with a remote membrane for ...
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63 views

The Einstein-Cartan equation as the “living heart of gravity”?

I recently read in A Journey into Gravity by Wheeler that "The Einstein-Cartan equation gives us the most vivid image that mankind has ever won of the living heart of gravity" (P.118) ...
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65 views

Do the matrices $S^{\mu\nu} = \frac{1}{4}[\gamma^\mu, \gamma^\nu]$ have a name?

Do the matrices $S^{\mu\nu}$ defined by $$ S^{\mu\nu} = \frac{1}{4}[\gamma^\mu, \gamma^\nu] $$ have a name ($\gamma^\mu$ are the gamma matrices)? They feel very important to me since they form a ...
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38 views

Mutually Commutative

What is the definition of a Mutually Commutative set of operators? I've found articles describing a complete set of mutually commutative operators, but I can't actually find what mutually commutative ...
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37 views

Motion Integrals of a Particle in a Force Field

I am trying to wrap my head around the following problem: A point particle is moving in a field, where its potential energy is U=-α/r. Find first motion integrals. In our university we have no ...
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41 views

How would you define a difference in potential?

I'm currently in 12th grade, and am required to write an essay about physics and biology. The topic of the essay is the artificial brain (with the researches of the Human Brain Project in Switzerland ...
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1answer
52 views

What are the differences between special and general relativity? [duplicate]

What are the differences between special relativity and general relativity? I am looking for a naive, non-mathematical explanation.
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27 views

Definition of a semiconductor

Originally I had learned that solids are split into two categories: isolators/semiconductors, and metals. The fundamental difference between the two is the existence of a bandgap. Metals don't have ...
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1answer
51 views

What does multi-periodicity mean in stellar pulsations?

How can there exist multi-periodicity in stellar pulsations? http://www.kitp.ucsb.edu/sites/default/files/kitp/preprints/moskalik2.pdf How can one visualize a multi-periodic pulsation or oscillation?
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1answer
52 views

What exactly is an image?

When we say several rays meet to form an image, what is that which is formed? Is it an arrangement of unknown entities? What exactly am I looking at when I see my image in a plane mirror?
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1answer
53 views

The name of effect of liquid flow inducing flow to neighboring layers of liquid?

How do you call an effect, when liquid or gas stream is involving the neighboring layers of matter also move? Like on videos of rocket engines testing, when exhausting gas sucks an air and steam from ...
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22 views

Relativistic non-linear Walecka model

What is meant by a relativistic non-linear Walecka model? What are some various sources to study it? [And why cannot Google show a satisfactory result to such a simple question?]
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1answer
38 views

Difference between astronomy and astrophysics [duplicate]

In my university, the department for astronomy and astrophysics are distinct. I want to know what's basically the difference between the two fields?
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44 views

Confusion about the use of the term “Phase Space” in Strogatz text

I've just started learning about Hamiltonian mechanics, and from the definition given in Taylor's classical mechanics, phase space must always have an even dimension. However, I recall from reading ...