# 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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### How does the Higgs field prevent the electron from going the speed of light?

Both the Photon and the Electron are point-like particles. Most massive particles can be thought of "bound collections of massless particles", but the electron assumed to be a "point particle with a ...
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### Would the results of the Double Slit Quantum Eraser be the same using massive particles?

I'm wondering if the double slit quantum eraser experiment would produce (or does produce, if it's already been done) the same results if massive particles were used instead of photons. My reason ...
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### What is a mass moment?

I am currently reading through a document Finding Moments of Inertia from MIT, page 4, and I am a little confused as to one of the concepts that they use. In this document, there is mention of a mass ...
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### Reference for the renormalization of a scalar field's mass

There are a couple of interesting lectures by Leonard Susskind online, and in the first lecture on Supersymmetry & Grand Unification he explains renormalization. His example is the mass ...
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### In special relativity is mass just a measure of all other energy than kinetic?

The energy momentum equation in special relativity is: $$E^2=(pc)^2+(mc^2)^2.$$ and it holds for a moving but not accelerating object. One special case is the massless photon: $$E=pc.$$ And another ...
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### How is mass accounted for when a particle is in a superposition? [duplicate]

When dealing with a particle as represented by a probability field, how is mass distributed across the field? Would the mass be averaged across the field?
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### Weight and Inertia (are they related?)

R. Feynman wrote in his lecture (The Feynman Lectures on Physics: Chapter-9) "Weight and inertia are proportional, and on the earth’s surface are often taken to be numerically equal, which causes a ...
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### Why are massive particles clocks? Or are they not?

I recently came across a public lecture "Dark matter decay?" by Sir Roger Penrose. In his lecture he states that the two equations $E=mc^2$ and $E=h\nu$ can be combined to form a formula for the ...
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### Correction to fermion mass in Supergravity mediated supersymmetry-breaking

I recently came across this paper about axino (fermion superparter of axion) mass in supergravity: https://doi.org/10.1016/0370-2693(92)90547-H In this paper, they think of a specific superpotential (...
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### Question about $E=mc^2$

When a nuclear reaction happens, the amount of mass disappeared satisfies $E=mc^2$. However, the reaction will stop at a certain point, there is no way to make the whole thing disappear into energy. ...
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### Force of baseball bat given force of ball and recoil distance

Say I swing a baseball bat and hit a ball. The ball is moving at 60 miles per hour and impacts the baseball bat squarely at that speed. The ball has moved twenty feet before impacting the bat. The ...
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### Showing $m_I = m_g$ follows from the equivalence principle

The inertial mass of an object is defined as its resistance to acceleration by $\vec{F}_{net} = m_I\vec{a}$. The gravitational mass of an object is defined as the scaling of the gravitational force an ...
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### Where is the mass of a proton coming from? From empty space or gluonfields?

Protons are made quarks and bosons. I think most physicists would agree that the mass of a proton is not coming from the quarks itself. About 90% is coming from something else, but what is that. I ...
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### How to use the concept of variable mass system?

The general equation of variable mass motion is as follows: It's derivation is given below: Refer wikipedia page for more details and the link of it is given below: https://en.wikipedia.org/wiki/...
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### What determines the diameter of a black hole?

I am wondering what determines the diameter of a black hole. Is it just the amount of mass it has consumed? If so why does that determine the diameter?
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### If inertial mass were equal to for example half of gravitational mass why would things not still fall at same rate?

I have read that it is the equality of inertial and gravitational mass that causes all objects to fall at the same rate irrespective of size. But if this were not true, what effect would we see? Would ...
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### Mass in general relativity (for black hole)

Based on my knowledge, we have several formalism to calculate the mass of black hole such as Brown-York formalism, ADM method, Hawking mass, Komar,... What is the difference between them and how ...
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### Peskin and Schroeder Section 7.1 Mass Shift

I'm slowly reading my way through Peskin and Schroeder. Near the end of section 7.1 they compare the mass shift of the electron from QFT to the classical value, both of which are divergent but in ...
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### How can I explain what a kilogram is using Planck's constant? [duplicate]

I want to understand what 1 kg represents. For example: I know that 1 second is equal to $9\ 192\ 631\ 770$ transitions from the microwave radiation that a cesium-133 atom (at $0$K) emits, if it's ...
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### Force = Mass ⋅ Acceleration [duplicate]

I have a doubt on the formula, $$F=m\cdot a$$ In pushing the wall, as per formula, $F= m\cdot 0=0$ as there is no acceleration hence zero. Therefore force become zero. But we have applied some force ...
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### Why is there a controversy on whether mass increases with speed?

Some people say that mass increases with speed, some people say that the mass of an object is independent of its speed. I understand how some (though not many) things in physics are a matter of ...
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### Why do objects with mass have gravitational force that is proportional to their mass?

Why do objects with mass have gravitational force that is proportional to their mass, i.e the larger the object the more gravitational force it has?
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### Why do two bodies of different masses fall at the same rate (in the absence of air resistance)?

I'm far from being a physics expert and figured this would be a good place to ask a beginner question that has been confusing me for some time. According to Galileo, two bodies of different masses, ...
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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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### Explanation on Newton's second law

I have asked a question on I pushing the wall,where the force of me is not zero but as per the formula F=m.a,the force is zero and then I got the answer , it is because here the net force is acting ...
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### Can the event horizon of a black hole increase its size due to accelerating mass?

Lets make this thought experiment. I throw a spaceship inside a black hole. Then, this spaceship start its motors and accelerates rotating around the singularity at great speeds. Due to relativist ...
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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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### Mass Luminosity Relation Review

I have read that exists a relation between the luminosity and the mass of a star $$\frac{L}{L_\odot}=\left(\frac{M}{M_\odot}\right)^a$$ with $a$ depending on the mass $M$. I have looked for a ...
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### Instantons, renormalization, and the Schwinger Model

Instantons in QCD contribute to the up, down, and strange quark masses (see, e.g., Georgi and McArthur (1981) or Kaplan and Manohar (1986)). Some papers claim that this contribution is equivalent to ...
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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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### Mass attached to another mass hanging from a hole in a table

I've been trying to understand the setup for the Lagrangian for this question from Morin: My issue is why would the mass ever rotate, assuming we release it from rest? Why does the setup of the ...