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Questions tagged [terminology]

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

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What is meant by cubic symmetry with regard to thin films growth?

I am reading a paper on epitaxial thin film growth of an alloy and it mentions that for one conditions the films grow with a cubic symmetry and for another they have an in-plane anisotropy. I would ...
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1answer
154 views
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Is the term “quantum triviality” defined by the UV or the IR behavior of the RG flow?

The Wikipedia page on quantum triviality seems to give two different definitions for the term that are not obviously equivalent. Some parts of the page seem to define a renormalizable theory as "...
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2answers
199 views

Natural convection and buoyancy: What is a better description of $g$?

In their derivation of the Grashof number (Gr), Çengel and Ghajar make the following comment: Note that there is no noticeable gravity in space, and thus there can be no natural convection heat ...
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1answer
53 views

Exact meaning of 'degree'

I wish to know if there is an exact meaning of degree in physics/math/chemistry. It is used in many cases and it is not clear to me which requirements must have an unit of measurements for carrying ...
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1answer
29 views

Specific term for a retractable lightsaber [on hold]

Okay so I know the title is a little weird, however, me and my former Chemistey teacher were talking and I was showing him a collapsible sword I printed and he said there was another name for the ...
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1answer
65 views

Why is the “fine structure” correction called that way?

I'm working on the fine structure correction to the Hydrogen atom. I have more of a conceptal, maybe historical question, why is this correction called this way? and why is the fine structure constant ...
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2answers
41 views

Do the terms “damping constant” and “damping coefficient” have standard uses?

I've heard the terms "damping constant" and "damping coefficient" used to describe both the $c$ from the viscous damping force equation $F = -c\dot{x}$ and the $\gamma$ from the definition $\gamma = \...
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1answer
48 views

Why do terms in a field theory Lagrangian that are polynomial in the fields collectively called the “potential”?

Field theory Lagrangians are often of the form of a kinetic term plus a source term minus a potential term. How do we know that the potential term is a polynomial in the fields? On a related note why ...
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3answers
348 views

Centrifugal Pump Head

What is pump head? and how is it different from the difference in elevation between the suction and delivery reservoir? Also why must the kinetic energy of the fluid leaving the pump must be least? I ...
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1answer
245 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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1answer
62 views

Different Schwinger-Dyson Equations

In the literature on QFT there are a lot of different equations that are all called "Schwinger-Dyson equation" so I wanted to know how are they related and if they have proper names. The first ...
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2answers
138 views

What does Carlo Rovelli mean by “blurring”?

In Rovelli's book The Order of Time, he often refers to blurring. Can you help me to understand what he means? He says we observe the universe from within it, interacting with a minuscule portion ...
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3answers
1k views

GR: Pseudo Riemannian or Riemannian?

Is General Relativityy described by Pseudo-Riemannian manifold or Riemannian manifold? I cannot understand the vast difference between the two manifolds. In books, General Relativity is looked as a ...
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1answer
35 views

Difference between Postulate versus Law

In quantum mechanic, we have many different postulates. In classic mechanic, we have different laws. As long as I know that physics's laws are temporarily correct until an anomaly. But what is the ...
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3answers
12k views

What sets a “Law” apart from a “Rule” or a “Principle”? [duplicate]

Basically, I understand the difference between a "Theory" and a "Theorem" but I am quite confused when it comes to "Law", "Rule" and "Principle". Can you make the differences clear to me?
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1answer
106 views

What is the mean ionospheric height?

I am reading some articles about the ionosphere and I am a little bit confused about the terms mean ionospheric height and effective height of the ionosphere. Are these the same thing? I would refer ...
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1answer
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Binding energy of a molecular ion?

The protons in the $\text{H}_2^{+}$ molecular ion are $0.106 \, \mathrm{nm}$ apart, and the binding energy of $\text{H}_2^{+}$ is $2.65\,\mathrm{eV} .$ What negative charge must be placed halfway ...
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3answers
11k views

What is a mode?

The word mode pops up in many fields of physics, yet I can't remember ever encountering a simple but precise definition. After having searched fruitlessly on this site as well, I feel that even ...
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4answers
321 views

Is there a scalar acceleration?

Distance is paired with Displacement and it seems to be a bigger idea than just the magnitude of Displacement. Speed is paired with Velocity. I have always thought that there is not such pairing with ...
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0answers
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What is the rate of change of speed called? [duplicate]

Magnitude of acceleration is definitely not the answer in case of rate of change of speed unless it it is moving in a straight path. So is there any name for rate of change of speed?
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2answers
1k views

What is atmospheric stratification?

In the context of atmospheric stability, what are the meanings of stable or unstable stratification? What is stratification?
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1answer
27 views
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1answer
35 views

What is proper name for non-inertial forces in GR?

General relativity works in all reference frames, so inertial forces are real in it. And due to the equivalence principle, gravity should be also considered inertial. So what is a good term for the ...
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2answers
42 views

Can displacement be negative after calculation?

Regardless of the positive or negative, doesn't the number determine the total displacement and not the sign in front of the numbers?
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3answers
2k views

What is the meaning of “matter” in physics?

What is the meaning of matter in physics? By defining matter in terms of mass and mass in terms of matter in physics, are we not forming circular definitions? Please give a meaning of "matter" in ...
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2answers
385 views

What is the linear attenuation coefficient and how does it relate to interaction probability?

I have misunderstanding the linear attenuation coefficient (L.A.C) concept. As known, L.A.C is depend on absorbed medium and energy of incident radiation. Supposing, L.A.C= 100 cm-1, how can this ...
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1answer
36 views

Rotational motion and Circular motion

What is the difference between rotational motion and circular motion? Are they same or they different?
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2answers
141 views

What is the difference between “uniform” distribution and “even” distribution?

I was reading a question in mechanics where it was written that mass of the rod is evenly distributed, but it was supposed to be "uniformly distributed". What is the difference between "uniform" ...
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1answer
389 views

What is the meaning of 'systemic velocity' of galaxies?

I came across the term systemic velocities of galaxies. Can you please explain what it means?
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0answers
61 views

Difference between Critical and orbital velocity

What is the difference between orbital and critical velocity of satallite ? I have read that critical velocity is constant value and it does not depend upon altitude. It only gives the velocity of ...
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1answer
88 views

Why are there lots of definitions for strain?

Why do we need Green or Almansi strains and what is True strain? I'm so confused about terminology.
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1answer
1k views

What does 'channel' mean?

I see many plots like the following that graph counts per channel, I know what a 'count' is, but I don't know what a 'channel' is. Could somebody please explain to me? My guess is that it is that ...
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0answers
48 views

Is Universal Law of Gravitation a 'law'? [duplicate]

My textbook mentions that the universal law of gravitation cannot be proved. If so, then why is it called a 'law' and not a 'hypothesis'?
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1answer
466 views

Variables in calculation of drag coefficient

Okay, so I looked up drag force equation, and I found that the equation involved the drag coefficient. Then I looked up the drag coefficient, and the equation for it involved the drag force. ...
3
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1answer
170 views

What's the difference between linearly polarised and plane-polarised waves?

To explain polarisation, my book gives an example of a transverse wave in a string, and explains as: Since each point on the string moves on a straight line, the wave is also referred to as a ...
3
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1answer
65 views

What Does Up-Down Asymmetry Mean?

There is strong experimental evidence (reported on in the linked paper), from more than one high energy physics experiment, that up-down asymmetry is present in the decays of certain charmed baryons. ...
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What is a “fiduciary” quantum state?

In Giovanetti et al.'s paper "Quantum Random Access Memory" (arXiv:0708.1879) they state: If the qutrit is initially in the $|wait\rangle$ state, the unitary swaps the state of the qubit in the two ...
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4answers
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Is Pauli-repulsion a “force” that is completely separate from the 4 fundamental forces?

You can have two electrons that experience each other's force by the exchange of photons (i.e. the electromagnetic force). Yet if you compress them really strongly, the electromagnetic interaction ...
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0answers
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How is this fluid motion called in English?

I am considering unsteady two-dimensional potential flow of ideal fluid. In the absence of active forces fluid motion is governed by equation $$ \rho \frac{d \vec{v}}{d t} = - \nabla p $$ where $\rho$ ...
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Is there a better name for flavour of particles apart from generation number? [closed]

If we assume the standard model falls into 3 generations ordered by mass. (This needn't necessarily be true.) We call these "generation 1", "generation 2" and "generation 3". So the property of a ...
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1answer
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Terminology: can I use the world “comoving” to describe a reference frame in which a certain object is at rest?

Here a question about terminology. Suppose I have a particle that is moving at velocity $\beta$ in the observer (or laboratory) frame. Now, is it appropriate / legitimate to describe the frame in ...
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Branch of Physics that Examines Atoms Relationships

Is there a specific branch of physics that can examine and calculate the strengths of atomic or molecular bonds and predict how they are going to break, putting into consideration the surrounding ...
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1answer
1k views

What is the Davis Equation and why is it used in a Train Simulator?

I have been trying to understand how Microsoft Train Simulator works and people seem to use some Davis equation to calculate friction. So my questions are: What is it? Why do they use it? Are there ...
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2answers
688 views

What does the term “inversion symmetric” mean?

I've read the responses to the question `"Lack of inversion symmetry" in crystal?' but I'm still unsure about the meaning of inversion symmetry. Which of the following two dimensional ...
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4answers
538 views

What are the differences between specific latent heat and latent heat?

What are the differences between specific latent heat and latent heat? As far as I know, latent heat is the heat required or released during the change of state, without change of temperature. So ...
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2answers
2k views

Difference between conduction current density & convection current density?

Could anyone please explain the difference between the conduction current density $J=σE$ and the convection current density $J=ρv$? I really appreciate any examples or applications to further ...
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4answers
55k 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 ...
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1answer
6k views

What is solid-solid transformation?

I found this solid-solid transformation in Wikipedia. http://en.wikipedia.org/wiki/Phase_transition#Types_of_phase_transition Please tell me what it is? It's present in types of phase transition in ...
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1answer
40 views

How to understand the kernel as a transition amplitude?

Consider the time evolution operator $U(t_f, t_i)$ that controls the evolution of a wave function according to $|\psi(t_f \rangle = U(t_f, t_i) | \psi(t_i) \rangle$. As I understand it, the Born ...
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0answers
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When talking about the rolling of an object (such as a wheel) what is the difference between sliding and slipping?

My question is rather simple. Concerning with the rolling motion, what is the difference between slide and slip?