Questions tagged [mass-energy]

The special-relativistic relation connecting energy with mass, $ E^2 - (m c^2)^2= (pc)^2 $. May be used to provide accounting constraints in energy and momentum, both conserved in total, even in reactions where $m$ is not.

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Why nuclear binding energy influence mass?

I do understand this from a energy point of view. However, let's consider a system with two small mass point in a classical case. The total mass of the system should be $M=m_{1}+m_{2}-\frac{E}{c^{2}}$ ...
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Why is mass a form of energy?

Why is mass a very concentrated form of energy? Does it have to do something with photons, phonons or nucleus?
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What are all the similarities between momentum and energy?

I noticed that there are a lot of similarities between momentum and energy, and it's almost like momentum is the time-like version and energy is the space-like version of the same thing. For example, ...
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Energy when near the speed of light

An unknown particle with rest energy of $1 \text{ MeV}$ is traveling with a speed of $0.6c$ along the $x$-axis in our rest frame when it decays into two photons, also travelling along the $x$-axis. ...
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$\beta^-$ and $\beta^+$ $Q$ value issue

It's unclear to me why the following doesn't work when I calculate the $Q$ value for $\beta^-$ and $\beta^+$ decay. If we start with a parent nucleus $P_z$ with $Z$ electrons decaying through $\beta^-$...
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Why is mass an invariant in Special Relativity?

I have read here that mass is an invariant and that it is the momentum that approaches infinity when your speed approaches the speed of light. That is why infinite energy is required to accelerate an ...
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Particle Physics - minimum energy for $p + p \rightarrow p + p + \bar{p} + p$ [closed]

A beam of protons with energy $E_p$ is made to collide with a stationary target and a search for the interaction $p + p \rightarrow p + p + \bar{p} + p$ is made. I have to estimate the minimum ...
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Human mass to energy equivalence

This article states that the average human has a mass energy equivalence of 7.8 septillion joules of energy Converting this into a temperature using $E=k_B T$, we have a temperature on the order of $...
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Is energy mass equivalence ficticious when not at rest?

Here are some examples from my textbook I will refer to, which I could not copy paste, I understand that $E=mc^2$ applies fine for thinking about rest energy, but when the body is not at rest, would ...
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Relativistic mass and energy

Why can't we use $\frac{1}{2}(\gamma m)v^2$ to calculate kinetic energy of a particle moving at Relativistic speed?
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What is the difference between 'Rest Mass', 'Centre of Mass' and 'Invariant Mass' in special relativity and particle physics?

Firstly, after reading this source, the length, $s$ of an energy-momentum four-vector is $$s=m_0c^2\quad\fbox{Rest Mass}$$ But, according to this, the length of an energy-momentum four-vector is $$...
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How is the time-component of the spacetime interval in a spacetime diagram related to the time component of the energy-momentum 4 vector?

In a spacetime diagram the spatialized time direction is the vertical $y$-axis and pure space direction is the horizontal $x$-axis, $ct$ and $x$, respectively. The faster you go and therefore the ...
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If a neutron decays to proton + electron, and a proton can decay into neutron + positron, doesn't this mean neutron = neutron + electron + positron?

I was just watching some videos and came across beta+ radiation (when a positron is emitted). It then occurred to me, how can the following be true, given that a positron and an electron have the same ...
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Can the total momentum in the centre of mass frame be non-zero?

I have a question regarding the usage of the centre-of-mass definition (which I thought required the total momentum, $p_T=0$) in the solution to the question given below: A particular centre-of-...
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Where does rest energy fit into the calculation of total energy?

Electron energy is often expressed as the sum of potential energy and kinetic energy : $$E = U + KE$$ In this case, where does the rest energy $511\ \text{keV}$ fit in? How can I reconcile these ...
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Can massless particle have effective mass?

The effective potential was probably very familiar in many concepts. However, what about effective mass? Suppose a massless particle. For simplicity, suppose it's not some superficial particle, i.e. ...
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Do the Broglie's equation or the Higg's field could give “mass” to a photon?

I know that there are probably hundreds of questions about the mass of a photon, but none of those questions was able to clarify me some problems. I was talking with a guy on Facebook that says that ...
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1answer
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Is energy needed to release or absorb energy?

Is energy itself needed to release or absorb energy? Or do all bodies have energy already to do work due to their mass ? Can light energy for eg. “absorb” more energy? For energy to be absorbed or ...
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A question about infinite energy

I know the conservation of energy doesn't allow that, and i saw a question on this forum about infinite energy: Why can't I do this to get infinite energy?, it says we can convert matter into ...
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How does introducing energy equal to the binding energy both overcome the strong force and increase the mass?

Let's say you have a deuterium nucleus, and you hit it with a gamma ray that has an amount of energy equal to the binding energy (2.224 MeV). That corresponds exactly to the increase in mass of the ...
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How come photons have no mass if they have energy and $E=mc^2$? [duplicate]

If photons have no mass, and yet have energy, how is that compatible with $E=mc^2$? Anything having mass should have energy (and the opposite should be true as well no)?
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What is Binding energy, actually?

I have read from my textbook about binding energy but it indicates two completely different ideas.I am listing them below: Definition (1): "Binding Energy : An atomic nucleus is a stable ...
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1answer
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Do all particles with zero rest mass and finite energy have to travel with speed of light in vacuum?

Suppose there exist particles with zero rest mass ($m_0=0$) which are not photons. Let them have a non-zero finite energy $E$. Do they also, just like photons, travel through space with the speed of ...
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Can we use $E=mc^2$ as the internal energy of gases?

I was studying the fluid equation in cosmology and saw that when they derive this equation from the first law of thermodynamics, they use $E=mc^2$ as the internal energy (of the universe maybe). Is ...
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Quantum energy levels vs. mass

TL;DR given a system comprised of two bound particles with masses $m_1, m_2$, and given energies of bound states $E_n$ between the two particles according to the non-relativistic Schrodinger equation, ...
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Confusion about conservation of energy in special relativity

In my special relativity course we defined 4-momentum $P$ as $mU$ where $U$ is the 4-velocity and $m$ is restmass. Then by definition $P$ is a 4-vector. We then defined $E$ via $E/c = P^0$ and claimed ...
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Doubts on mass-energy relation

Einstein gave this mass-energy relation $E=mc^2$. But, using simple mathematical transposing, we get $E$ divided by $m$ equals $c^2$, which gives kinetic energy by mass equals a constant $9×10^{16}$. ...
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(possibly silly) question about the energy-momentum relation

On the wikipedia entry for the energy-momentum relation, it states that, for certain systems, $$ E^2=(pc)^2+(m_0c^2)^2 $$ where $E$ is total energy, $p$ is momentum, $m_0$ is rest mass, and $c$ is the ...
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Mass-energy equation vs chemical bonding reactions

If use $E=mc^2$ in chemical energy like needs to bonding and ...  it means there must reduced or added some mass after reaction, by Wikipedia mass-energy equivalence: Because the speed of light is ...
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Is $E=mc^2$ contradicting conservation of energy? [closed]

If we state that, on one hand, energy is conserved because : $$\Delta PotentialEnergy+\Delta KineticEnergy=0 \tag{1}$$ And we state on the other hand that: $$Energy=mc^2 \tag{2}$$ Don't we run ...
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1answer
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Nuclear binding energy and mass defect

Kenneth S. Krane, Introductory to Nuclear Physics, defines mass defect as Δ=(m(A,Z)-A)$c^2$, where m is the mass of the nucleus with atomic number Z and mass number A and he says that given Δ, we can ...
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On the change in half-life of tritium traveling at near $c$ in a cyclotron

Barring physical effects I do not know about, I would expect that the beta decay of tritium of about 12.32 years to increase by the time dilatation accorded to its increased mass while traveling in a ...
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Relating $p, E,$ and $m$ to $\gamma$ and $\beta$ (Special relativity)

In my QFT textbook this relation appeared $$\frac{p}{E + m} = \frac{\gamma - 1}{\gamma\beta},$$ where $p$ is $|\vec{p}|$, the modulus of the momentum, $E$ is the energy, $m$ the mass, $\beta = V$ (we'...
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Is it in principle possible to store energy more efficiently (per kg) than as antimatter?

I'd like to understand if there's a theoretical bound on how efficiently you could, in principle, store energy to be used for propulsion. The important quantity to consider is energy stored per kg of ...
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1answer
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Need help understanding a radioactive decay question

I have the following question: A stationary nucleus of uranium-$238$ undergoes alpha decay to form thorium-$234.$ The following data are available. Energy released in decay $4.27 MeV$, Binding ...
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Does the equation $E=mc^2$ hold good for the non-fissionable materials also?

Though we know that the equation $E=mc^2$ holds good for the fissionable materials, I want to know whether this equation holds good for non-fissionable materials also or not? I want to know whether ...
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1answer
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When is a body at rest?

I wonder when a particle is considered at rest. I'm aware that this is commonly given when all forces balance each other out. I'm more interested how the rest energy $ E = mc^2 $ has to be understood ...
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Is every chemical reaction a nuclear reaction?

This is a PhD-level question that I'm sorry to say is likely to annoy many a high school teacher or university professor trying to get their students to understand the difference between chemical and ...
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Relative mass and Gravity [duplicate]

According to relative mass effect predicted by Einstein's relativity theory, the mass of an object increases with increase in it velocity given by the equation $$ M = \frac{M_0}{\sqrt{(1 - v^2 / c^2)...
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1answer
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Mass-Energy-Space equivalence [closed]

If the speed of light in a vacuum is $c=\frac{1}{\sqrt{\mu\epsilon}}$ and energy of mass at rest in a vacuum with no gravity is $E=mc^2$, shouldn’t $E=\frac{m}{\mu\epsilon}$ or $m=E\mu\epsilon$ be ...
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When we say energy curves spacetime, which is the cause and which is the effect?

I read that energy is one of the parameters (physical properties) that contributes to the curvature of spacetime, then there is the math proof using General Relativity. I was wondering because common ...
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Does the energy and/or mass of an electron change during the act of measurement and so the wavefunction collapse?

In the double-slit experiment, if we want to know which slit did the electron go through, we have to use a laser that gives an energy to the electron. Now, I have two questions: 1. Does the energy of ...
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359 views

Does a charged particle have more mass than an uncharged particle? [closed]

I was just thinking about Einstein's famous $E=mc^2$, and how it equates energy to mass and mass to energy. I was wondering, if the charge is a measure of energy, then if a particle accepts a charge ...
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Why is the constant $c$ replaced by velocity $v$ in this particular derivation?

Is this derivation for de Broglie's wavelength correct? If yes, why is it that we're changing $c$ to $v$? Is that allowed? If we use that logic and reverse engineer the whole derivation, we get $E=...
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Can the Higgs particle escape a black hole? [duplicate]

The higgs particle or field is what gives mass to everything. It's said that nothing can escape a black hole. If that is true how can the black hole "tell" its mass as even the higgs would not be able ...
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Can the mass of an object account for the total internal energy of the object?

While studying thermodynamics my book describes the quantity the internal energy of a system. My book states: The concept of internal energy of a system is not difficult to understand. We know that ...
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Could 2 collided neutron stars partialy lose mass?

If two collided black holes lose a huge part of their masses before collision do a pair of neutron stars lose such quantity of mass and is the density of an astronomical body the cause of how much of ...
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1answer
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Clarification regarding the mass-energy equivalence

In this recent question: As neutrons are more massive than protons does Sun increase mass while fusioning elements? It is stated that not only does the Sun not gain mass, but it loses mass at 4 ...
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As neutrons are more massive than protons, does the Sun increase its mass while fusioning elements?

Where is the mass coming from when neutrons are produced from protons in the Sun? If a positron is made, will it possibly annihilate with an nearby electron?
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Matter/energy conversion?

What known physical processes convert matter into energy? What known physical processes convert energy into matter?

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