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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1answer
207 views

Degrees of freedom in double Atwood machine?

Why the degree of freedom in double Atwood machine (one block on one side and a pulley with one block in its each side on other side) is 2 and not 1? According to the formula $s=3*n-m$; where ...
5
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2answers
3k views

What Exactly is a Shock Wave?

The Wikipedia defintion of a shock wave pretty much sums up all I've found online about what a shock wave is: A shock wave is a type of propagating disturbance. Like an ordinary wave, it carries ...
1
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1answer
34 views

Conditions for free fall

What are the conditions at which free fall occurs? If a body is falling freely under the effect of gravity only without external resistance, the motion is called free fall. This definition gives me ...
0
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1answer
36 views

What is the exact mathematical definition of oscillation/vibration?

My question is basically is what criteria need to be fulfilled to decide wether a motion is osciliiation/vibration or not. I found two definitions, def1: "moving around an equilibrum", def2: ...
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2answers
4k views

Exactly how much lift is needed to overcome the weight of an average person?

I am designing a "glider" of sorts, and I have some basic questions about the physics involved to get me started. How much lift is required to overcome the weight of an average person, say 150 pounds? ...
3
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1answer
47 views

Difference between Fermi and Riemann normal coordinates

What is the difference between Fermi normal coordinates and Riemann normal coordinates? Which one of them is related to the vanishing of the Christoffel symbols?
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1answer
40 views

Angular momentum definition? [closed]

The definition of linear momentum is this: Momentum is a vector quantity defined as the product of an object's mass, $m$, and its velocity, $\vec v$. So According to that definition,The definition ...
0
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3answers
128 views

Does the work done by a person equal the work done on the object in this situation?

If you applied a constant force over a floor that has friction on an object, would the work done by the person equal to the work done on the object? Assume that the floor is flat and that the object ...
0
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1answer
44 views

What is the difference between the potential difference and potential energy of an electron?

What is the difference between the potential difference and potential energy of an electron? Let's take an example the potential difference (PD) across a resistor. if there's a current flowing, the ...
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5answers
525 views

Definition of entropy in thermodynamics

In most textbooks, the definition of entropy in reversible processes on a system $S$ is given simply as $$d S=\delta Q/T.$$ It seems to me this definition is insufficient since it does not specify ...
4
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1answer
3k views

Why is the mechanical advantage of a wedge = length of slope/ width?

Mechanical advantage is defined as Force Output/Force Input For a symmetrical wedge with the length of the slopes being equal and the width being the distance between the end points, the articles ...
3
votes
1answer
280 views

What is the meaning of “moment”?

What is the meaning of moment? I'm little confused about the word as there are some terms like moment of momentum, moment of mass, moment of force, etc. I want to know what exactly is meant by the ...
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0answers
33 views

What is the general definition of a quench?

I've seen the term "quench" used in many different contexts. It's easy to understand the meaning when the context has a simple physical analogue, such as lowering the temperature of a system to cause ...
0
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1answer
28 views

Earth, Sun and beginner's reference frames

In the post-Newton era, where "absolute space" is not absolute, how is the reference frame in which "the Earth moves round the Sun" accurately defined?
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2answers
31 views

How can you tell if the work done by a force is negative?

This is kind of confusing to me. I'm guessing that it's specific to the problem. Is the work done by friction always negative? Is the work done by gravity always negative? Spring as well? It seems ...
0
votes
1answer
24 views

What is difference among the consepts: bulk free energy, cohesive energy, Gibbs free energy, binding energy?

I am working on size dependent surface energy of metals. I need to know the different energies between the atoms. Different papers use different energies but their meanings seem alike, therefore they ...
0
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1answer
40 views

A conceptual question about work

Consider an object of mass $5kg$ on a plane. If a horizontal force of $10N$ acts on the object for a time interval of a second. Calculate the work done on the object by the force given that the ...
2
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1answer
49 views

Reversible process, equivalence of two definitions?

There are two common definitions of a reversible process: A reversible processes is quasistatic with no dissipation. And A process where an infinitesimal change in conditions would reverse ...
0
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1answer
35 views

Rheological Definition of Friction

I was listening to a record at our university about friction and its rheological definition. For the first moment I thought that its the normal definition Friction is the force resisting the ...
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0answers
14 views

What does 'fully excited' actuallly mean?

In statistical mechanics you often here the phrases such as 'when the degrees of freedom are fully excited then....'. An example would be the validity of the equipartition theorem. But what is the ...
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2answers
37 views

Definition of translational , rotational , rolling motion

What are the exact definitions of pure translational , pure rotational and rolling motion ? I am a class 11th student ... I find it difficult to exactly make a difference between translational , ...
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4answers
29 views

Is impedance the ratio of voltage to current at any instant?

My book defines impedance as the ratio between the amplitude of voltage to that of the current (Vmax to Imax), I just wanted to make sure whether its also true for the instantaneous values of voltage ...
1
vote
1answer
216 views

What is many-body bound state?

Bound state by definition is a state when particles are bounded together, so then "many-body bound state" would be bound state for a system of many bodies. Then I have several puzzles: is the state ...
2
votes
2answers
6k views

Does a force do work on an object with constant velocity?

I know that a force does no work on an object if the object's displacement is zero, but if an object is moving at a constant velocity $\bar{v}$, and a force $\bar f$ (let's say that $\bar f$ and $\bar ...
0
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1answer
40 views

Work done by a force

What is the difference between work done by a force and work done against that force? Is it true that work by a force = -(work against that force)?
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1answer
210 views

Is displacement in circular motion a chord or an arc?

When taking the displacement between two points along a circular path to calculate its velocity, do you take the length of a chord connecting the two points or do you take the length of the arc ...
-1
votes
1answer
48 views

What is difference between 9.8 N (Kgwt) and 9.8 m/s^2 (g)?

What is difference between 9.8 N (Kgwt) and 9.8 m/s^2 (g)? What is difference between kg weight and gravity? I am not so good in physics so please explain in a lot of detail (but sorry for this silly ...
2
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1answer
51 views

Why does this formula for the partition function not include the multiplicity?

I am having problems understanding the formulas used for describing the partition functions and the probability distributions for canonical ensembles. In the first case I have two formulas for the ...
3
votes
3answers
198 views

Why is the definition of inertial mass circular?

On Wikipedia, the definition of inertial mass is: Inertial mass is the mass of an object measured by its resistance to acceleration. And, can be evaluated using $F = ma$, Newton's second ...
-2
votes
1answer
64 views

What is the difference between the Lorentz force and the ponderomotive force? [closed]

I understand that Lorentz force is due to motion of moving charged particle in a magnetic field, and I imagine that ponderomotive force is mechanical version analogy to a person surfing on a wave ...
0
votes
1answer
21 views

Clarification regarding Homogenous systems in Thermodynamics

So i have just started with Classical Thermodynamics..and i am reading Thermodynamics by Bruno LinderSo I could not understand what he means in this portion- If intensive properties are uniform ...
5
votes
1answer
487 views

Hamiltonians, density of state, BECs

When working with Bose-Einstein condensates trapped in potentials, how can one tell what the density of state of a system of identical bosons given the Hamiltonian, $H$? (I have been told that it is ...
0
votes
2answers
127 views

How are unitary matrices and unitary random matrices associated with physics or quantum mechanics? [closed]

Please forgive my ignorance, my back ground is not physics. I am looking for distance measure between two unitary matrix (for my work). So my starting point is where else unitary matrix is ...
1
vote
1answer
750 views

Conventional definition of ideal fluid

According to Landau&Lifshitz, an ideal fluid is one with zero viscosity and a negligible thermal conductivity. This is also the FR.wikipedia version: En mécanique des fluides, un fluide est ...
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3answers
1k views

What exactly is the “coherence” between waves?

I know, by definition, that coherence means that a pair of waves have constant phase difference. What does this mean? Does it mean they always have a 360 degrees, or 0 degrees phase difference? Or ...
4
votes
2answers
37 views

Does a central force have to be independent of angle?

When defining a central force, some sources, like Wikipedia, say that the magnitude of the force only depends on the distance $r$: In classical mechanics, a central force on an object is a force ...
2
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2answers
824 views

Susceptibilities and response functions

It is often confusing whether a susceptibility is the same as a response function, specially that often they are used interchangeably, in the context of statistical mechanics and thermodynamics. Very ...
4
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2answers
57 views

Difference between two types of pressure

When I first studied thermodynamics the concept of pressure was defined by means of the fundamental relation $S = S(U,V,N)$ for simple systems. The pressure was thus defined by $$P = ...
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2answers
1k views

Can we define tension in a string as the reactive force produced in a string being pulled at both ends?

In my textbook, the definition of tension was given that Tension is the reactive force which exists when string is being stretched at its both end. After it there was a case given that to calculate ...
1
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1answer
380 views

Null lines and degenerate plane

Can anyone explain me what null lines are and degenerate plane? I don't know anything about it, I don't have physics background and I am a mathematics student and please tell me if there is any good ...
0
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1answer
100 views

What is a clear definition of vibrons?

What is a clear definition of vibrons? Vibrons are localized Phonons and I need more information about them. It is somewhat vague to me. Can you give some references, please?
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2answers
226 views
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0answers
51 views

What is the difference between thermodynamic and empirical temperature?

When I've studied Thermodynamics I did so in Callen's book and there the author talks about temperature as a single thing, which mathematically is simply defined as: $$T = \dfrac{\partial U}{\partial ...
1
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1answer
37 views

Scientific definitions of “moment (of)” and “instant”? [closed]

What are the scientific definitions of "moment (of time)" and "instant"? Are they different with their definitions in everyday language? I also don't know the definitions in everyday language, of ...
0
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0answers
34 views

What's meant by D dimensional gas?

As Avagadro states: "One mole of an ideal gas at STP occupies 22.4 liters." This doesn't seems counterintuitive since we know that we need a volume to compress the gas. But how can we explain quantum ...
2
votes
5answers
249 views

What exactly is work?

What exactly is work? My book confuses me: a force can lift an object to a height h, or it can accelerate an object through gravity. In all these cases, a force displaces an object and change the ...
1
vote
2answers
88 views

Physicists definition of vectors based on transformation laws

First of all I want to make clear that although I've already asked a related question here, my point in this new question is a little different. On the former question I've considered vector fields on ...
2
votes
1answer
55 views

Is there some physical intuition behind Clifford Algebras?

The mathematically rigorous definition of a Clifford Algebra is as follows: Let $V$ be a vector space over a field $\mathbb{K}$ and let $Q : V\to \mathbb{K}$ be a quadratic form on $V$. A Clifford ...
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3answers
120 views

What is the difference between toy models and normal models? [closed]

Here is the short description of scientific model: an imperfect or idealized representation of a physical system And the definition of toy model: a simplified set of objects and equations ...
0
votes
1answer
26 views

conditions for something being being considered as a system? [closed]

without loss of generality can somebody answer the question in reference to a car being towed by a truck. I am asking this question because the work done by the truck on the car is different at ...