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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.

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Free fermion Lagrangian invariance under chiral symmetry

I want to apply this transformation to a free-fermion lagrangian: $$ L=\bar{\psi}(\gamma^\mu{\partial_\mu \,- m)\,\psi}$$ $$ \psi ' =\psi\; e^{i \alpha \gamma_5} $$ $$ \bar{\psi}'=\bar{\psi} \;e^{-i \...
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Magnetic field like phenomenon associated with Gravitational Field [duplicate]

Like in electrodynamics we have magnetic fields associated with electric fields, is there something similar related with gravitational fields too? I mean both are quite similar fields...(Maybe I'm ...
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Does the mass of a beaker filled with water change due to a mass partially submerged in it?

I believe it should be different as there is upthrust acting on the second block and hence by Newton Third's Law it should act back on the liquid adding to more weight. The answer is given isn't so as ...
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Relativistic mass effect

Does relativistic mass phenomena only appear while accelerating or even when the object is travelling at constant velocity (say 90% speed of light)?
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Are conservation of mass and conservation of energy *independent* constraints for physical systems?

I'm modeling fluid systems and want to use conservation of mass (aka 'continuity') and conservation of energy as constraints to help solve for certain system parameters. But it occurred to me that the ...
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Theoretically, if you could attach a 1 meter string with a weight on the end to the exact center of the earth what would it do? [closed]

Would the mass of the weight keep moving towards the center but overshoot and repeat the process?
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A particle of mass $M$ decays into two particles of mass $m_{1}$ and $m_{2}$ [closed]

I can't understand how to get what the problems asks for: A particle of mass M decays into two particles of mass $m_{1}$ and $m_{2}$. A detector measures your energies and moments like this: $$E_{1} =...
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Balancing forces between two point [closed]

In this special machine, there is mass M with length LM from joint C and height HM. There is two point A and B with length LA and LB from joint C respectively. Point A and B are fixed but joint C can ...
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Concerning the increase in mass as velocity increases [duplicate]

This increase in mass is relativistic. Let an object approach the velocity of light, as it does we as observers notice that its moving very slowly, and it's mass is increasing significantly. What ...
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Which is more fundamental property of matter: charge or mass? [closed]

I haven't got a whole satisfying answer to this question. I think that matter can exist without charge but it can't exist without mass. Am I correct? So this fact may be answered by asking about the ...
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Meaning of mass-deformation in string theory and quantum field theories

I was reading some papers in the ABJM theory. I keep reading the term mass deformation but am not sure what it really means. I think the papers assume the reader is familiar with the term. Example ...
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Did the Chernobyl power station's water cistern really hold $7000\:\rm m^3$? [closed]

In he HBO TV miniseries Chernobyl, they talk about a cistern holding 7000 cubic meters of water. That is the content of Loch Ness, the deepest lake in the UK. Would the Chernobyl reactor really hold ...
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Why gravitational mass and inertial mass being same was a problem before Einstein solved it?

Why is it so that Einstein is credited with telling us the reason for the equivalence of inertial and gravitational mass of an object? Did Newton ever make a distinction between the two masses? What ...
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Accelerator on a Turntable [closed]

If a circular particle accelerator were placed on a "frictionless" turntable and then turned on, would it spin opposite to the motion of the accelerating particles?
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Force measurement [closed]

We have a bike and a biker on it of mass 81 kg combined. Biker can reach speed around 30k/h. And the question is: how to measure the force (in Newtons) applied on the bike to reach that speed in 10 ...
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How do we define “mass” in the context of particle physics and relativity?

In laypersons terminology, mass is defined as the amount of matter. However, consider the following: The $W$ and $Z$ bosons have mass. An antiparticle has the same mass as its corresponding particle. ...
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What's the simplest way to measure mass without using gravity?

I'm putting together some rough ideas for physical experiment designs and datasets, relating to multiple hypotheses for quantum gravity. Because I'm working on experiments to test theories of gravity,...
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How to know how the self-energy changes the mass?

Suppose we have a Green's function of the typical form \begin{equation} G(k)=\frac{1}{k^2-m^2-\Sigma(k)} \end{equation} where $\Sigma(k)$ is the self energy of that particle. How exactly can we ...
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How is water heavier than petrol, even though its molecular weight is less than petrol?

Molecular weight of petrol is so much higher than water, but when it comes to physical property, weight, one litre of water weighs more than one litre of petrol. How is it possible?
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Theoretical values of radius and mass of O9.5 II star?

Where to find please theoretical values of radius and mass of O9.5 II star? I mean something like: http://www.mpe.mpg.de/~martins/pub/calib_Ostar.pdf However, there are only O I, O III and O V stars ...
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How does the gravitational acceleration on a surface of planet change, if its radius shrinks while retaining the same mass? [closed]

If the radius of the earth were to shrink by $1$% while its mass remained the same, then how would the acceleration due to gravity on the earth's surface increase by $2$%?
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Masslessness of Goldstone Bosons

I have a question about the origin of the massless nature of Goldstone bosons. This is what I understood: we know thanks to Goldstone's theorem that from the breaking of continuous symmetries emerge ...
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The existence of Delta baryons was experimentally proven? [duplicate]

If we will look at the table from Wikipedia of their properties, we will find the same mass for all. That looks like a result of some calculation, rather then a result of measurement. Was that ...
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What is the way to work out the running of lepton masses?

If we assume the GUT unification energy is some value E, (say $10^{16}GeV$). Can we work out the running of the particle masses for example the electon, muon and tau at various energies? And will ...
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Is spacetime volume preserved in presence of a mass in General Theory of Relativity (GTR)?

In many publications about the warping of spacetime in presence of a mass the metric of spacetime is stretched, expanded : http://discovermagazine.com/~/media/Images/Issues/2015/april/relativity.jpg ...
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Would the Earth have weighed the same if no life had developed on it?

I was reading this question and talking about it with my flatmate when a question came up. Ignoring the effects of losing or gaining mass due to cosmic dust, meteorites, and atmospheric losses as ...
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Forces on a railway track with curvature and cant (inclined plane)

I'm trying to work out the forces acting on the left and the right rail if the track has curvature and cant (i.e. is an inclined plane) I've come this far as you see in the picture but I'm struggling ...
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Weighing machine, kg vs. N

When I stand on a weighing machine and it shows me the number 75 , is it my mass in Kg or the Normal Force due to gravity in N
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How much energy from air to ice? [closed]

If... "A" is the mass of air (standard air composition and pressure) "I" is the mass of ice "V" is the volume of the box where the change of heat happens (no heat interaction with out of the box) ...
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Some neutrino anomalies that need explanation

It is inferred that the neutrino must have mass, but beyond saying this mass is incredibly minute nobody has ever measured it. All other particles which have mass also have charge,can be slowed down,&...
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Why can't we have a massive photon in the Standard Model of Particle Physics

I've heard that in the Standard Model of Particle Physics you can´t have a massive photon whatever you do but I'm having a few problems showing that. I understand that the trick to make this work is ...
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SI redefinition of the kilogram - what is one measuring? [duplicate]

I have been reading about the new SI units and specifically, want to get a better understanding of the definition of a kilogram. It was written that the kilogram will be defined in terms of Planck's ...
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Why is it that the equation of a massless scalar field *must* be conformal invariant?

I'm reading a paper [1], p.111 where it is said that: However, the equation of scalar field with zero mass must be conformal invariant while equation $\square\varphi=0$ does not satisfy this ...
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How to measure mass using centripetal force?

I was just reading through Volume I, Chapter $9$ of the Feynman Lectures, where he's discussing Newton's dynamics. He says, We use the term mass as a quantitative measure of inertia, and we may ...
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A query on Newton's second law [duplicate]

Upon studying Newton's second law, I noticed that it seems less of a physical law i.e. outcome of some experiment, than something we built upon how WE define mass and force. The ratio of the masses $...
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Black hole gravity and light [duplicate]

When an object is squeezed to it’s swartzschild radius it becomes a black hole (made by density) and it’s mass does not change (it’s gravity doesn’t change), but if it’s mass doesn’t change (it’s ...
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Why does the reconstructed mass of a particle have a fairly wide distribution?

In HEP experiments, a particle of interest (e.g. Higgs) is reconstructed using information about decay products, momentum, energy deposits, angle of those particles, etc. The invariant mass of the ...
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Mass of the mesons in a universe with massless quarks

As I propose in this post, About the mass of the particles, imagine a universe with massless quarks due to Higgs' VEV is exactly zero. In our universe, where quarks are massive, we have consider ...
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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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What would happen to our universe if an object of infinite mass suddenly appeared? [closed]

The scenario is this: randomly, an object of infinite mass but of a limited size appears in our universe. What would happen to the rest of the universe? My intuition is that everything else in the ...
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Why can I throw a larger stone farther than a smaller stone?

Recently I was throwing stones(don't ask me why) when I noticed that there seems to be an optimum weight of stone so that it travels the farthest. If I generate the same amount of force each time(and ...
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What is wrong with the energy of a particle, of which the mass increase with time?

Let a particle move in space with constant velocity $v$. Its mass is directly proportional to time: $m=\mu t$, where $\mu$ is a constant with dimension kg $\text{s}^{-1}$. A single force acts on the ...
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Increased mass of compressed springs [closed]

Based on the idea that mass is an emergent property of fundamental particles with potential energy bound in a restricted space, I want to make a macroscopic analogy. I want to put compressed springs ...
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4answers
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How to understand force given an inconstant mass?

I am wondering about what force really is after I have looked up wikipedia, where there is stated that $F=ma$ only holds to be true for a constant $m$. For inconstant mass force is: $$F=\frac{dp}{dt}=...
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Mass splitting for leptons and down quarks in $SU(5)$ model?

In the minimal $SU(5)$ GUT model, the masses of the leptons and the corresponding down-type quarks must be equal. i.e. $m_e=m_d$, $m_\mu=m_s$, $m_\tau=m_b$. Whereas this is approximately correct for ...
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What if Force was not Mass times Acceleration? [closed]

We know that Force equals Mass times Acceleration, $F = ma$. But what if we had a law like $$F=m^2a$$ or $$F = 2ma~?$$
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What is the origin of neutrino mass? [duplicate]

Standard model shows zero mass for neutrino and seesaw model explains why the neutrino mass is so small. But to show that the neutrino mass is small, the mass should be originated by some mechanism. ...
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Why Aren't Hadron Masses More Useful In Determining Standard Model Constant Values?

Some of the most exquisitely precise experimental measurements in all of physics are the masses of the various hadrons. Consider these examples: the proton mass is known to eleven significant digits. ...
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Hierarchy problems: calculating the mass of the Higgs vs. other SM particles

While reading up on hierarchy problems in particle physics (wikipedia), I stumbled onto the statement that in the Standard Model, there is no hierarchy problem (or at least it cannot be formulated) ...
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How to derive: $\frac{E^2}{c^4} = \frac{p^2}{c^2} + m_0^2$?

My teacher wrote the following equation on the board a few days ago: $$\frac{E^2}{c^4} = \frac{p^2}{c^2} + m_0^2$$ And I got no idea how this is derived especially since we already derived that: $$m^...