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 don't strings have a Planck mass of vibrational energy?

It is claimed that strings have a length $l_S$ within an order of magnitude of the Planck length $l_{Pl}=10^{-35}$ m. If they oscillate at the speed of light, $c=10^8$ m/s, then their natural ...
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Will my mass be greater in deep space compared to when I am on Earth?

Imagine a huge hand picks me up and takes me away from Earth. Will my mass increase as I move away? I am asking this because when we try to separate a nucleus into its constituent nucleons, the total ...
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Energy released from destruction of an object [closed]

In the movie “Star Wars: A New Hope”, Luke Skywalker blows up the „Death Star‟. Assume that the „Death Star‟ is a perfectly spherical spaceship with uniform mass distribution. The mass of „Death Star‟ ...
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If two neutron stars of opposite spin collide will the resulting body have less mass due to lack of rotational energy?

If two neutron stars of opposite spin collide will the resulting body have less mass due to lack of rotational energy? Will the Penrose proccess lead to less gravitational mass?
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Centre of mass reference frame of a particle and a photon

If we consider the reaction of a gamma photon with a proton, e.g., $$\gamma + p \rightarrow p + \pi^0$$ I wonder what would the linear momentum of the initial proton in the center-of-mass reference ...
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How was mass increase measured? [closed]

Wiki (https://en.wikipedia.org/wiki/Electromagnetic_mass) says that: Thomson (1893) noticed that electromagnetic momentum and energy of charged bodies, and therefore their masses, depend on the speed ...
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Converting between mass and binding energy in semi-empirical mass formula

The semi-empirical mass formula is given in terms of the binding energy as: $$ B(Z,N) = aA - bA^{\frac{2}{3}} - s \frac{(N-Z)^{2}}{A} - d \frac{Z^2}{A^{\frac{1}{3}}} - \frac{\delta}{A^{\frac{1}{2}}}$$ ...
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How weak are the Van der Waals bonds? What is their contribution to the total mass of an object?

We know that every binding energy can be expressed as a negative mass contribution to the total mass of the system. It is well known, for example, that composite nuclei have a “mass defect” when ...
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Why is internal energy of nucleons ∝ to binding energy? [duplicate]

In fusion , as two light nuclei fuse , the relative binding energy experienced by each nucleon is increased and hence the internal energy of the nucleons is decreased which by E=mc² causes a decrease ...
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Nuclear binding and internal energy [duplicate]

A section of some article: When you cool a body at rest its internal energy decreases. Since energy is related to mass, here $E=m_0c^2$, where $m_0$ is the rest mass, the rest mass of the body ...
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Strong nuclear force in fusion

I have read that there is an increase in the amount of the binding energy from the reactant nuclei and the product nucleus during nuclear fusion and this causes the decrease the internal energy (...
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Does a spinning disk weigh more than when it is stationary?

Relativity tells us that mass increases with velocity, does this mean the faster a disk spins the more it will weigh? If so, is this measurable with current technology?
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Conversion of mass into energy [duplicate]

If mass can be converted into energy , then doesn't it violate law of conservation of energy because one form of energy can be produced from another form of energy . But here in this case energy is ...
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Energy of particle in equilibrium

Suppose I have a mass let say a mass of M kg Imagine, it is in equilibrium No force is acting on it Due to no force its energy must be zero . But why it is said that mass at rest also has energy ...
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Does the mass in $E=mc^2$ change with the speed of the mass? [duplicate]

I was involved in a discussion on Quora about going faster than the speed of light and I pointed out that $E=mc^2$ implies that the faster the mass goes the more energy you would obtain from it. One ...
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Why is energy released when nucleons come together to form a nucleus?

Binding energy is defined as the energy required to split a given nucleus into it's individual protons and neutrons. But why when nucleons are combined they release energy? What is the origin of this ...
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Why can we consider the rest mass of photon is zero?

Because a photon has a momentum, we can calculate the relativistic mass of it according to the special relativity. Also according to this theory, the relativistic mass is proportional to the rest mass ...
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Momentum and Kinetic energy from a decay of single particle at rest into 2 particles

How can I find the kinectic energy $KE_n = E_n - m_nc^2$ and the momentum $ p_n = \frac{1}{c}\sqrt{E_n^2 - m_n^2c^4}$ From $E_n = (\frac{m_{\lambda}^2 + m_n^2 - m_p^2}{2m{_\lambda}})c^2$, which result ...
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Why there is no reaction Deuterium + Deuterium $=\rm {}^{4}He$?

Why there is no reaction like $D+D={}^{4}He$ specified here and in other places like this? Apparently $2\times2.0141-4.0026=0.0256$ is positive. What is the problem with this reaction?
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Potential energy, mass transformation in energy? and nuclear reactions?

Lost mass is converted into kinetic energy after nuclear reactions but what happens to potential energy? (in the case of a non isolated system) I don't know a lot of potential energy and in my idea it ...
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Why can't a mass be accelerated to the speed of light if its mass does not increase with speed? [duplicate]

My question is similar to this question (If rest mass does not change with $v$ then why is infinite energy required to accelerate an object to the speed of light?) except that my question 1. is not a ...
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In special relativity, is it true that mass is conserved and energy is conserved?

If so, it would seem to follow that a photon has mass, because an atom that emits a photon loses mass. If the photon has no mass, then the total mass will be less and mass will not have been conserved....
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Origin of Nuclear fusion energy

What causes the mass of the two reacting nuclei to convert to energy and if it is for a purpose then why is it released. What is the source for this cause (if there)?
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Why do mass terms in QFT couple to gravity?

In QFT (or a classical field theory for that matter) mass terms appear as quadratic terms in the Lagrangian. For example for the Klein Gordon equation with metric signature $(+,-,-,-)$ we have $$\...
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Inertial vs gravitational mass at different temperatures

So, I know more energetic objects have more mass according to Einstein. I'm aware that this has been verified by weighing an object at different temperatures where the object weighed more at higher ...
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Is massenergy an outdated concept?

Do physicists working on relativity still use the concept of massenergy? Do they still say that mass and energy are the same thing? Einstein coined the term "massenergy" to make clear, he ...
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How much energy is there in curved spacetime of a black hole?

Given that gravitational waves transmit energy, the curvature of spacetime must, itself, contain energy. How do you calculate this energy? Specifically, I'm most interested in how one would calculate ...
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Loss in mass due to energy decrease

As an object cools down it looses energy. As $E=mc^2$ I would also assume this would correspond to a decrease in the mass of the object. When the energy is released from the substance this corresponds ...
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Mass-Energy equivalence - speed of light? [closed]

According to Einstein, $E=mc^2$. Is $c$ always the speed of light in vacuum in this equation? And for the relativistic mass: $m=\frac{m_0}{\sqrt{1-(v/c)^2}}$ does the same hold for $c$ here? So if I ...
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Do electric fields in a capacitor add to its weight?

So this article got me thinking: https://www.scientificamerican.com/article/do-electric-charges-and-m/ It states that according to GR, the energy in an electric field should curve spacetime and ...
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Linus Pauling, General Chemistry 1-2 - Does Light has mass?

Linus Pauling, General Chemistry 1-2: "...it was pointed out by Einstein that energy also has a mass, and that light is accordingly attracted to matter by gravitation." Isn't that wrong? ...
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Mass: a form of energy [closed]

Einstein's $E=mc^2$ and law of conservation of energy implies that mass is a form of energy, but if it is a form of energy then why can we freely interact with mass while the other forms of energy are ...
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Can force change mass in a system?

My physics teacher defined force as "an agent that may change the shape, state of motion, size, or mass of an object" but I disagreed with him about "mass" being changed in any ...
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Energy in nuclear fusion - mass change vs potential energy explanation

Trying to understand how the energy related to nuclear reactions. In particular why particular fusion of small nuclei release energy. So far, there seems to be two explanations which I have ...
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How limit is changed while deriving $E = mc^2$?

While deriving $E = mc^2$ I found following in book by Arthur Beiser : In non relativistic physics, the kinetic energy of an object of mass m and speed v is $\mathrm{KE} = \frac {1}{2} \ mv^2$ . To ...
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Sources of Mass in Special Relativity

Let, we have an object with mass (previously called rest mass) m. It starts moving with a velocity v, and its relativistic mass (not a preferred term nowadays) or total energy becomes $m_{\mathrm{Rel}}...
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Is spacetime curved by relativistic mass?

The top answer to this question asserts that only rest mass curves spacetime. My poor understanding of the EFEs & special relativity is that $T_{\mu\nu}$ doesn't care about what whether energy ...
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Which of these sentences best describes the equivalence between mass and energy? [closed]

Which of these sentences best describes the equivalence between mass and energy? mass is a form of energy. mass and energy are two manifestations of the same property: mass-energy. mass is energy ...
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What percentage of a Proton's mass is potential/kinetic energy?

So in an hydrogen atom, the total mass of the atom is equal to the masses of the proton, the electron, minus their net binding energy of around 13 eV. Making the total less massive than the sum of its ...
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Is $E=mc^2$ relevant while accelerating a book across a table?

I'm having a difficult time making the connection between the Newtonian conception of mass and that proposed by special relativity and particle physics. From a Newtonian perspective, mass is that ...
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What's the reason for this apparent coincidence?

If we calculate the electrostatic potential energy of two protons in a nucleus, it's approximately $$\frac{e^2}{4 \pi\epsilon_0 (2r)} = 1.15 \times 10^{-13}J$$ where $r$ is the radius of the proton, ...
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Questions about Antimatter [closed]

Antimatter. It's a thing that exists and it's something that I wanna learn more about. Just gonna jump straight into the questions this time around instead of drawing things out with a long-winded ...
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Is mass really lost in favor of energy after fission?

If in nuclear fission, the sum of the masses of the resulting atoms is the same as the parent ($\text{U}_{236}$, after fission is $\text{Cs}_{93}$ + $\text{Rb}_{140}$ + 2 neutrons), where does the ...
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Why is energy produced from uranium not exactly mass times velocity squared?

Our technology teacher explained why $1 \;\text{kg}$ of enriched uranium does not produce $$E=(1 \;\text{kg})*c^2$$ [where $c$ is the speed of light], but I didn't get it, so why is this so? (Nuclear ...
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A situation where mass and energy are separately conserved?

I know that in a closed system mass+energy is always conserved. For example, in an exothermic reaction, some mass is converted to energy. Now, I'm looking for a situation where mass and energy are ...
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Have there been any studies on the mass/energy that thoughts produce? [closed]

I am very interested in the concept of energy and manifesting a desired reality (which is more so thought of as spiritual or metaphysical rather than scientific). However, I do believe there is a ...
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135 views

What is Energy? Like, seriously, what is it? [duplicate]

Here's a question that's been on my mind for quite some time now. What the actual hell is energy? Like, seriously. I understand real-life is nothing like fiction where characters and machines can ...
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4answers
409 views

Nuclear reaction: loss of mass or conservation of mass?

Certain particles come together to form a nucleus, this causes a certain amount of energy to be released in the form of photons, the mass of the nucleus is less than the sum of the masses of its ...
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Are neutrinos' velocities related to their energies? As they are with other particles?

I have read extensively about neutrino energies, including in the popular press, and yet velocities of the neutrinos themselves (not the detectors they 'run into' or the leptons they 'create' after ...

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