Questions tagged [definition]
The definition tag is used in situations where the question is either about how some term or concept is defined or where the validity of an answer depends on a subtle definition of some term or concept used in the question.
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How to use the definition of a rank-$2$ tensor for this kind of examples?
Suppose that, a rank-$2$ tensor transforms as
\begin{align}
T'^{ij}=\frac{\partial x'^i}{\partial x^k}\frac{\partial x'^k}{\partial x^l}T^{kl}.
\end{align}
How to use this criterion to investigate if ...
- 195
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What is the connection between moments in probability theory and the moment of inertia?
My question arises as the moment of inertia (MOI) has been described as a second moment.
In my understanding if the MOI is indeed a second moment of a distribution of mass, this suggests the MOI could ...
- 13
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Photoelectron and electron in photoelectric effect [closed]
Could you please help me find some answers, as I have been stuck in this for a while and didn't get understandable answers.
what is the difference between the photo electron and an electron.
The ...
- 11
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What exactly is equivalent resistance?
We all know the basic example of school with series and parallel resistors, so they might be a good place to start.
Given two terminals $A$ and $B$ from a circuit, if the current that exists $A$ is ...
- 153
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What does the $F$ in Newton's second law equation mean?
This is a super simple question: does $F$ represent the net force exerted on an object or the force it exerts on another object as a result of momentum? Say a ball is rolling. In this specific ...
- 539
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4
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91
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What are internal and external forces?
what is internal and external force? How do I decide what forces are internal and external?
in work-energy theorem and conservation of mechanical energy, do we consider internal, external, or both ...
- 91
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Why is warming food in the microwave work and not heat? [duplicate]
In Schroeder's An Introduction to Thermal Physics, heat is defined as the "spontaneous flow of energy from one object to another" and work is defined thermodynamically as any other transfer ...
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Second derivative of energy with $k$
In solid-state physics, we often encounter the velocity operator (e.g. this post) which the eigenvalues can be written as
$$
V^\mu(\vec{k}) = \frac{1}{\hbar} \frac{\partial E}{\partial k^\mu} \biggr|_{...
- 843
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Meaning of $n$-critical point
My lecture notes about field theory refer to a tricritical point as a point in which a continuous phase transition line meets a discontinuous phase transition line.
In the following it refers to a ...
- 111
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Is the definition of geodesics different if the electromagnetism is added to GR?
In plain GR, geodesic are defined by:
$$ \nabla_{u} u^{\,\mu} = 0 $$
where $u^{\,\mu}$ is the four-velocity of the particle.
Now, I don't understand if this holds true also in the electromagnetic case,...
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What is the relationship between Clausius Inequality and 2nd Law?
I am confused about the application of the 2nd Law for reversible and irreversible processes and cycles.
I want to know how the Clausius principle, the Kelvin-Planck statement, and the Clausius ...
- 31
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Clarifying the definition of pressure in statistical physics
I am studying David Tong's lecture note on statistical physics, and I have a question regarding the precise definition of pressure. I checked other postings in this community, but was unable to get ...
- 173
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Two values of Rydberg Constant
In my textbook I came across two values of Rydberg Constant:
\begin{align}
R&= 109\,677\ \mathrm{cm}^{-1}
\\
R_h&= 2.18 × 10^{-18}\ \mathrm J
\end{align}
when we are calculating energy of the ...
- 83
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What is $r$ in a metric signature in general relativity? If $v$ and $p$ are the time and spatial coordinates?
The Wikipedia article on metric signatures says that the signature of a metric can be written $(v,p,r)$, where $v$ is the number of positive eigenvalues, $p$ is the number of negative eigenvalues, and ...
- 4,509
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Rest Mass Energy
What exactly is the Rest mass energy? I know the usual goes Like it is total energy stored in mass $m$ that is in Rest. so for someone moving relative to the frame that the mass $m$ is in (a rest ...
- 73