Questions tagged [mass]

The property of an object that determines how much it responds to a force in Newtonian mechanics, and how much it interacts with gravity in the Newtonian framework. Mass also refers to the intrinsic energy of a particle in particle physics. This tag does also cover effective mass.

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What is the fermion mass matrix for a Yukawa Lagrangian?

For a 2-scalars theory like $$\mathcal{L}_{\phi\varphi}=\frac{1}{2}(\partial\phi)^2-\frac{m_\phi^2}{2}\phi^2+\frac{1}{2}(\partial\varphi)^2-\frac{m_\varphi^2}{2}\varphi^2+\frac{\lambda}{2}\phi^2\...
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How to understand the mass in the definition of momentum in quantum mechanics?

I am looking at the definition of momentum in Griffiths, which is $$\langle p \rangle = m\frac{d\langle x\rangle}{dt}.$$ So as I understand it, the velocity here tells us the rate of change for the ...
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Mass-energy equivalence and gravitational potential energy

If mass and energy are equivalent, and if gravitational potential energy is energy, why doesn't an object have more mass when it is at a higher altitude? Does the mass-energy equivalence work for ...
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Why is there still disagreement over the mass of the bottom (or beauty) quark, but none of the others?

Wikipedia (among other places) lists two values for the alleged mass of the B quark, 4.18 and 4.65 GeV. Only one of the two possible masses listed has a link to another Wiki page explaining the ...
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Is Feynman right? Does mass change with speed? [duplicate]

In chapter one of Feynman's famous Lectures on Physics, he writes the following. Mass is found to increase with velocity, but appreciable increases require velocities near that of light. A true law ...
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What is the origin of the inertia?

Is there any explanation why it is harder to move an object with more mass than an object with lesser mass? What kind of force is opposing our force? Is it finalized currently and well known what the ...
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Write the expression for $j$ in the case where the semiconductor has a scalar effective mass, along the $x$ axis there is a temperature gradiententer [closed]

Write the expression for $j$ in the case where the semiconductor has a scalar effective mass, along the $x$ axis there is a temperature gradiententer image description here
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If a proton travels exactly at 99% of speed of light are the individual velocities of the quarks inside it also exactly 99% of $c$?

If a proton travels exactly at 99% of speed of light are the individual velocities of the quarks inside it also exactly 99% of $c$? So can we think that they all travel linearly as the center of mass ...
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Is the mass of a particle taken as an exact number by empirical experimentation?

In this question the first comment says that it would be easy to test for variation in mass of particles, but none has been seen; so I wonder: Is the mass of a particle an exact number by experience? ...
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How do Vector-Like Quarks behave differently form SM quarks?

For context, I have to calculate a box diagram with this Lagrangian with Vector-Like Quarks (VLQs): $$\mathcal{L}=\bar{Q}(\not D -M)Q+\bar{U}(\not D -M)U+y(QH^cU+\text{h.c.})+\mathcal{L}_\text{kin}$$ ...
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Can we deduce the conservation of mass in non-relativist physics or is it just an experimental fact? [duplicate]

It is a well-known fact that mass by itself is not conserved (since, for example, a particle can annihilate with its antiparticle). However, in classical physics, and as long as there is no physical ...
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Could an experiment be performed to decide if information has mass? [closed]

I read in a (non-mainstream) article that there is an equivalence between information (Shannon entropy) and mass-energy (here). Could we design an experiment to see if this actually is the case? It is ...
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Does the gravitational constant $G$ impact the density parameter $\Omega$?

As far as I'm aware, for baryonic matter the estimated mass density is $\Omega_{\rm m} = 0.044 \pm 0.004$ If in some other universe $G$ was say $22\times$ what it is in ours, is there a linear ...
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Are all particles massless before supersymmetry breaking?

I am having troubles to understand the breaking mechanism in a supersymmetric theory. There is said that a particle and its superparticle have the same mass. Since no superpartners have yet been found,...
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What are some non-entertainment, real-world applications of more complicated mass-spring models?

What are some non-entertainment, real-world applications of more complicated mass-spring models? E.g. 3D models and models involving springs to multiple directions. So far these have seemed a bit too ...
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Tightly bound energy configuration for nucleons?

In fusion, why are nucleons of the product nucleus tightly bound and in a lower energy configuration than the nucleons in the reactant nuclei? I think the reason a large amount of energy is released ...
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Klein-Gordon equation with imaginary mass

I was wondering if someone could provide me the name of the following equation $$\square \varphi - \tilde{m}^2 \varphi = 0,$$ where $\square := \partial_t^2 - \nabla^2$. I am specifically seeking ...
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I was reading a question where it asked if astronauts on space shuttle lost weight would the spacecraft velocity increase? (Assuming closed system)

So a lot of the answers had to do with conservation of momentum and the method in which the mass was lost. Also how a shuttle in orbit speed has nothing to do with mass as its velocity has more to do ...
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Scalar field mass alteration due to interaction term $\mathcal{L_{int}} = \mu^{2}\phi_1\phi_2$

With non-interactive (free) Action of two scalar fields $\phi_1$ and $\phi_2$ I add an interaction term $\mathcal{L_{int}} = \mu^{2}\phi_1\phi_2 \ \ $ i.e.: $$S = S^{free}[\phi_1, \phi_2] + S_{int} [\...
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Why is the center of mass of this system moving?

Here in this question , considering the system to be the thread , ladder and man , we can say that as the gravitational force which is and external force equal to 2Mg is acting in the downward ...
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Interpretation of momentum in special relativity

Consider an inelastic collision between two particles $A$ and $B$ of the same mass $m$, such that after the collision they come to rest WRT an inertial frame K. In this frame, both the particles ...
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Notion of mass of a quantum field theory in AdS space-time

Consider a scalar field theory in $AdS_{d+1}$ spacetime \begin{equation} S= -\frac{1}{2}\int d^{d+1} x \sqrt{-g} (\partial_\mu \phi \partial_\nu \phi g^{\nu \mu} + m^2 \phi^2 ) \end{equation} On ...
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Does the degree of freedom change with speed for massive particle?

There are 2 degrees of freedom for a photon. But how many are there for massive particles and will this change with speed?
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Gravitational Force in a two hollow identical spheres? [closed]

Two identical hollow spheres of negligible thickness are placed in contact with each other. the force of gravitation between the spheres will be proportional to (r = radius of each sphere): R R² R⁴ R³...
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Neutrino field is left-handed

Why if we take the mass of neutrino to be zero then we get only left-handed field when $\psi_r=\frac{1}{2}(1+\gamma^5)\psi$ and $\psi_l=\frac{1}{2}(1-\gamma^5)\psi$ has no dependence on mass?
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Confusion regarding calculation of amount of water in container to ensure lowest centre of mass

When I tried to calculate the volume of water that should fill a massed container such that the centre of mass of the system is the lowest, I obtained two separate results when two different methods ...
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Why is it said that the lightest neutrino is relativistic?

The neutrinos from the cosmic neutrino background have a temperature of $T_\nu=1.945K$, that is an energy of $E=\frac{3}{2}k_BT_\nu$. If the neutrino's mass is around $0.1eV$ $$ \frac{3}{2}k_BT_\nu<...
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Force, opposite direction [closed]

Force of constant intensity of 25.5 N acts on the block as shown in the figure, with the block moving 7.2 m to the right. Determine the work done by the force. Friction can be ignored. W= F × s × cos ...
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Finding the maximum velocity that can be achieved by a critically damped spring (simple harmonic oscillator)?

If you have a mass-spring simple harmonic oscillator, with a mass of $m$, spring coefficient $k$ and damping coefficient $c$, the critical damping condition as shown here and here is defined by: $$ω = ...
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which force should come out to be the same in both frames

Suppose that a long cart is moving at a constant relativistic speed with respect to the ground. Sand is falling on it from negligible height(from the same place and zero horizontal velocity with ...
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How exactly can we shake an object to determine its mass?

It's often said that inertial mass is a measure of how hard it is to shake an object (as distinct from gravitational mass, which is how hard it is to lift an object in a gravitational field). Because ...
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As a binary system start producing gravitational waves even before merge should the stars start losing mass while still orbiting each other?

As a binary system start producing gravitational waves even before merge should the stars start losing mass while still orbiting each other? But is this really difficult to understand as just orbiting ...
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What's the minimum possible mass of a stable neutron star? [duplicate]

What's the minimum possible mass of a stable neutron star? Let's say you have a neutron star and slowly take away it's mass, e.g., either by firing a stream of anti-neutrons or by proton decay, since ...
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Force of an accelerating ball? [duplicate]

By Newton's second law, we know that $F=ma$. If I were to drop a ball from some height, it would accelerate to the ground with gravitational acceleration. But if I were to drop the same ball from a ...
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Do electrons have inertia?

I don't know quantum mechanics and know a little bit about mechanics and a very little bit about subatomic particles but I am just a curious to know the answer to my question. My question is if '...
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What would be the value of $c$ where $c$ is the speed of light?

From the equation of $E=mc^2$, where $E$ is the energy, $m$ is the mass and $c$ is the speed of light, so from that we can get $c=\sqrt{Em}$, again from the equation of $\lambda=v/f$, where $\lambda$ ...
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How the pressure will change inside a pressure chamber if there is a hole in the pressure chamber?

Let's say I have a pressurized tank with a fixed volume(V), I have 400psi of pressure inside it. Now a hole/orifice of 2mm diameter is made in the tank. Obviously, the pressure will now start leaking ...
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What is the physical significance of the running mass $m^2(\mu)$? [duplicate]

In QFT under the $\overline{\text{MS}}$ subtraction scheme the renormalized mass $m_R$ becomes a $\mu$-dependent quantity which "runs" via a differential equation $$\frac{1}{m_R^2}\frac{d ...
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How does massless particles arise in string theory when it starts with the assumption that all strings are composed of massive little pieces? [duplicate]

I saw in a lecture (see after 00:55:00) by Leonard Susskind, he write Polyakov action, saying that the string is supposed to have divided into several pieces with mass (he says that it is the non-...
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Why is inertia connected with mass and not momentum? [duplicate]

When my teacher was teaching us $E=mc^2$, he told us that the relativistic mass of an object increases when the speed increase. He told us that it is due to the increase of inertia. He said that as ...
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Extension in Massive Springs under gravity

Suppose we have a spring which has a uniform cross sectional area $A$, and has a uniform linear mass density $J$, and has a total unstretched length $L$. Let the spring also obey Hooke's Law. Further, ...
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Negative potential energy

In fusion of hydrogen into helium, hydrogen has negative potential energy which adds up and results in a mass defect.. Doubts:- Why is there negative potential energy between the nucleons in a ...
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Is it a pre-requisite for something to have constant mass to be a 'system' in Mechanics?

I deal sometimes with control volumes, and we have closed systems, in Newtonian mechanics we often just describe a 'system' without defining if it's closed or open, if we have a 'mass flow' such as a ...
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What is the general dependence of volume change from mass change due to general relativity?

The volume excess of earth due to general relativity in comparison to euclidean space has been calculated to $$ \Delta V = \frac{ G M \pi R^2}{5 c^2} = 113 km^3 $$ (this is done in this physics....
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Effective masses of spring-mass systems [duplicate]

It is known that the effective mass of the spring in this vertical spring-mass system(figure can be viewed by the following Wiki link) is 1/3 of the mass of the spring, for example, if the mass of ...
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Why does Newton's second law involve mass?

Once one has learned of Electromagnetic force, they see that the amount of force experienced by particle given a field is proportional to the particles electric charge. Similar situation the ...
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Nuclear fusion mass defect and energy production

In researching the topic of nuclear fusion, I have a few doubts related to the mass defect, 'negative' potential energy and resultant energy released as a by-product of nuclear fusion. When two ...
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Kinetic energy of quarks and mass of proton

I read that: Most of a proton mass comes from the energy of motion of its three quarks and from the energy carried by the gluons that keeps them confined together. Does kinetic energy of the three ...
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What is the exact ratio of dark energy to mass?

I need to know the exact ratio between mass and dark energy (total dark energy in the universe / total mass in the universe). I could only find it to 2 decimal points (0.68). I need this to make this ...
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Angular momentum of an extended mass for fixed origin imply the same result for nonfixed origin?

Consider an extended mass (say a collection of n particles where the internal force between them is central). For any fixed origin/inertial reference frame, the angular momentum satisfies $$\begin{...
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