# Tagged Questions

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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### Question regarding the mass of an alpha particle when travelling at a speed approaching the speed of light [duplicate]

The speed of an Alpha particle is: 10^7 m/s. This is a speed approaching the speed of light. hence, should the (relativitic) mass of the Alpha particle vary?
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### Have hypothetical particles with gravitational mass unequal to their inertial mass been proposed in the past, e.g. as candidates for dark matter?

This is a question about history. To my understanding the equivalence of intertial and gravitational mass for all known particles is a weird empirical coincidence that has been confirmed to high ...
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### How to model vibration damped by applied/contact force?

I am computer science student and I am working on a project which needs to know how the vibration of phone is damped by applied force (when human touches the phone). I have read many articles about ...
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### Why is $V=(1/2) m^2 \phi^2$ for a free relativistic scalar field of mass $m$?

Bit of a basic question here but how come for a free relativistic scalar field of mass $m$ such as Klein Gordon theory, we take the potential to be $$V=\frac{1}{2} m^2 \phi^2$$ Is the mass term ...
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### What is the relationship between the “mass” of QFT and that of Newtonian mechanics?

In QFT we work with Lagrangians which contain terms $m$ such that the relativistic relation $E^2 = p^2 + m^2$ is satisfied. By classical analogy $m$ is called the 'mass'. We note that due to the ...
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### Speed of light, lasers and mass

Hopefully this isn't a bad question. Light travels at the speed it does and nothing else can travel that fast because things have mass, correct? Or at least correct on an elementary level. And if ...
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### Can the Higgs mechanism provide complex masses for quarks and neutrinos?

Can the Higgs mechanism give complex masses to quarks and neutrinos, or is only real mass generation possible? There exist complex phases in the CKM and PMNS matrices, can they be explained through ...
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### Do all black holes have the same mass density? [duplicate]

I have been reading about black holes in Stephan Hawking's 'A Brief History of Time'. Then I was reading more about it on Wikipedia; I am making a school project on it. I do not really remember what ...
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### Electric skateboard speed calculations [closed]

I have a slight issue figuring out how the mass of person (≈110kg) will affect the theoretical top speed achieved. Below are the details: (1) Motor kv : 270 kV (2) Batteries: 19.8V Motor Speed: ...
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### How can one interaction influence the way another interaction generates mass?

This question arose as a follow-up of this one and applies generally to all interactions and all ways to generate mass. To make it clear, I take here the example of the neutron, whose mass is in ...
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### What is the effective electron mass in a plasma?

Is there a way to calculate the effective electron mass in plasmas? Effective electron mass is usually defined as varying from the vacuum electron mass in solid state physics. However, momentum ...
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### Where does mass come from in pair production?

In pair production, two gamma rays with > .511Mev can come together to create a positron and an electron. So two electromagnetic waves E and B fields, with No mass and No gravity and traveling at ...
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### How does mass change with speed? [duplicate]

While reading a textbook on Physics, I came across this : Mass is a universal constant. It does not depend upon the position of the body on the Universe but it changes with speed of the body. ...
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### Does the (relativistic) mass change? Why?

I learned recently that when an object moves with a velocity comparable to the velocity of light the (relativistic) mass changes. How does this alteration take place?
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### Neutrino oscillation and mass [closed]

Neutrino oscillations indicate that neutrino have little bit mass. Among three neutrinos - electron, muon and tau neutrino - which is heavier? What is the mass range of these neutrino?
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### Confused by gravity and weight [closed]

I know that $F = mg$ so $2,00 \textrm{ KG m} \cdot 9,81 \textrm{ N g} = 19,62 \textrm{ N F}$ Why does my book say that the weight of a $2,00 \textrm{ KG}$ object is $19,62\textrm{ N}$, the mass is ...
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### Gravity amplifier

Just a hypothetical question. Is it possible to increase or amplify gravitational interactions between two or more bodies ( without changing the mass)? Will changing the graviton ...
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### What is the relativistic mass of this spinning ball? [closed]

Relativistic Mass is: $$m_r = \frac{m}{\sqrt{1 - v^2/c^2}}$$ So Einstein says that the faster an object moves, the more mass it gains (relativistic mass). So suppose you have a spherical ball ...
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### Stabilizing a rotating wheel with a changing center of mass

Imagine a rotating wheel. For simplicity's sake let's assume it's not under the influence of any significant external forces (including gravity). This wheel is hollow, and objects inside are ...
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### Derivation of $E=pc$ for a massless particle?

In classical mechanics, massless particles don't exist because for $m=0$, $p=0$. The relativistic relation between energy, mass and spatial momentum is: $E^2= (pc)^2 + (mc^2)^2$ . So it is said that ...
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### Off-shell degrees of freedom of a massive vector field [closed]

A gauge boson is described by a vetor field $A_{\mu}$, so in four dimensions $\mu$ runs from $0$ to $4$ and thus $A_{\mu}$ has $4$ degrees of freedom (d.o.f), but the gauge invariance ...
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### Regge trajectory and Kaluza Klein tower

The mass of hadrons in the Regge trajectory scales as $m=\sqrt{\frac{J}{\alpha}-\alpha_0}=\sqrt{\frac{n}{\alpha}-\alpha_0}\propto \sqrt{n}$, where $J=n$ is the spin of the particle (in natural ...
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### Constant in Regge trajectory

The Regge trajectory in QCD is given by $$m=\sqrt{\frac{J}{\alpha}-\alpha_0},$$ where $m$ is the mass and $J$ is the angular momentum of the hadrons, $\alpha=(4\pi\sigma)^{-1}$ is the inverse QCD ...
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### What is the smallest item for which gravity has been recorded or observed?

What is the smallest item for which gravity has been recorded or observed? By this, I mean the smallest object whose gravitational effect upon another object has been detected. (Many thanks to Daniel ...
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### How is the total mass of Andromeda determined?

I am currently attempting to use Doppler shifts on both the advancing and receding sides of the galaxy to determine the mass. I am not sure exactly how I would convert the advancement and recession ...
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### Will my mass increase in my perspective while approaching near the speed of light?

Suppose I start my journey by a spaceship accelerate the velocity to 0.7c from Earth. Now the question arises that- Will my mass increase gradually as I'm going to a speed of .7c in my perspective and ...
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### Spring mass on a rotating disc

I demonstrated the problem in the figure below. Edit: Original figure is 90 degrees rotated clockwise. I couldn't rotate the figure here. Disc is massles and horizontal. Vibrating mass only moves ...
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### Cumulative mass & mass distribution of a disc galaxy

Hernquist has a great formula to represent the cumulative mass of a spherical galaxy (8): http://star-www.st-and.ac.uk/~hz4/contempastro/hqm.pdf 1) Is there any simple formula for disc shaped galaxy ...
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### Extra mass due to near light like speeds [duplicate]

Why does mass seem to increase as you near the speed of light?
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### Mass term in field Lagrangian

In the Klein-Gordon or in the Dirac Lagrangian density, the mass term is quadratic in the field. The other way around, I have heard a quadratic term in a general Lagrangian density be referred to as a ...
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### Weight difference on full moon and no moon day [duplicate]

Since Moon has an impact of gravity, would same piece of mass be heavier on a no moon day (since moon is at opposite side, thus pulling downwards) and lighter on full moon day (since the moon is at ...
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### Neutrino oscillations versus CMK quark mixing

I wish to describe in simple but correct terms the analogy between the Cabibbo–Kobayashi–Maskawa (CMK) and Pontecorvo–Maki–Nakagawa–Sakata (PMNS) matrices. The CMK matrix describes the rotation ...
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### QCD condensate and lepton mass

I read that the QCD U(1) anomaly is caused by the QCD condensate giving rise to quark masses. Does the QCD condensate also give masses to leptons (electron, mu, tau, neutrinos), or are these masses ...
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### Anomalies, neutrino condensate and neutrino masses

Is neutrino number conservation not affected by the U(1) QCD and QED anomalies due its zero U(1) charge? Is this the reason why the neutrino should be massless and there should be no lepton family ...
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### Mass, density and gravity for 2D SPH

Having previously only worked with 3D sph, the 2d case is confusing me. The concept of mass and density as well as gravity is not easily converted, as I see it. As an example in 3D I take 1000 ...
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### Moment of Inertia of a Motion Simulator Frame

I have a rather specific question. I'm trying to build a motion simulator for flight and racing sims, similar to this: https://www.youtube.com/watch?v=JQAZB3EnI_w . The basic concept is a platform ...
108 views

### Are mass and angular momentum related at a quantum level?

Is the mass of an atom related to the amount of angular momentum it contains? It makes sense to me that since the waveform of an electron is much much larger than a particle in the nucleus that its ...
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### Why does the Gravitational Potential energy formula indicate that heavier masses in the same point in the field have lower potentials?

$$U = -\frac{Gmm_E}{r}$$ Intuitively, it'd appear that the further away two objects are, the greater their gravitational potential, and this is confirmed by the gravitational potential formula. The ...
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### Where does a hadrons mass come from [duplicate]

So I've come to the understanding that a hadrons mass does not come from the constituent quarks but instead comes from a combination of things like binding energy and the mass energy of virtual gluons ...
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### How are mass and density treated in general relativity? [duplicate]

Background: I am confused by how mass relates to the equations in general relativity. For example, given a certain mass density distribution, I am unsure how to express a system in terms of GR. ...
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### Why does mass not matter on how quickly an object falls? [duplicate]

I've seen all the mathematical proofs and physics demonstrations in vacuums. However, for example, if a hammer falls to the Earth it falls very quickly. But, it can be interpreted another way. The ...
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### Measuring a rotating shaft's torque [closed]

My question is, there is a rotating shaft and I want to measure its torque. I don’t know its $r$ and $F$ but I connected a thread to the end of shaft to see how much weight it can lift and it is 2 ...
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### Did the mass of the electrons went infinite in the experiment done by William Bertozzi in the 1960s?

it is impossible to accelerate a particle to a speed greater than c, no matter how much kinetic energy we give it In an experiment published in 1964, electrons were accelerated to a large voltage ...
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### Why is the $S_{z} =0$ state forbidden for photons?

If photons are spin-1 bosons, then doesn't quantum mechanics imply that the allowed values for the z-component of spin (in units of $\hbar$) are -1, 0, and 1? Why then in practice do we only use the ...
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### Negative mass? How it works and can it travel the speed of light? [closed]

If something with mass can't travel at the speed of light, how about an object with negative mass (hypothetically). Can somebody describe how negative mass works and what it is?
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### Why must inertial mass and gravitational mass be equal, not just proportional?

I'm certain I'm just under a grave misapprehension. I really just don't understand how one can conclude that inertial mass is equal to gravitational mass. It seems to me that we've simply scaled our ...
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### If there turns out to be matter with negative mass, would there also be antimatter with negative mass?

I just heard of the concept of negative mass. Googling led me to see that the concept of negative mass is often contrasted with antimatter. This made me to wonder whether there would then also be a ...
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### Why does a black hole grow when it consumes matter? Isn't this a contradiction?

I've been thinking about this for a while but can't get my head around it. A black hole's mass is such that its gravity can overcome light. Its event horizon, as I see it, is the boundary up to which ...