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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Why don't strings have a Planck mass? (version 2)

The Energy $E$ of a fundamental string due to its length $L$ goes like $$E\sim TL$$ where string tension $T$ is given by $$T \sim \frac{1}{l_P^2}$$ (Using natural units $\hbar=c=1$ with planck ...
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Is there any known experimental violation of Einstein's $E=mc^2$?

Note that I am not talking about $E_0= m_0c^2$ but $E=mc^2$, where m is the relativistic mass. I know that one holds for stationary particles, moving particles, even light, I read that it even holds ...
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Why don't strings have a Planck mass?

I understand that strings have a size of roughly the Planck length $l_P$ of $10^{-35}$ m. If that is the case then one would expect that their mass would be roughly the Planck mass which is an ...
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Mass parameters in the spontaneous symmetry breaking

In Ashok: Lectures on Quantum Field Theory Sec. 7.5 p.279 he discusses the mass parameters for the potential $$ V = -\frac{m^2}{2}(\sigma^2+\xi^2) + \frac{\lambda}{16}(\sigma^2 + \xi^2)^2. $$ My (...
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Is rest mass determined by the kinetic energy of inner particles?

I haven't studied physics in many years, please forgive my lack of proper formalism. With that being said... The total energy is a function of rest mass energy and the velocity of the object, and is ...
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Is there a need to consider the relativistic mass when calculating gravitational potential energy?

The equation for gravitational potential energy is: $$V(r) ={GMm\over r}$$ In the reference frame where $M$ is stationary. I am wondering for mass $m$ here do we need to consider its relativistic ...
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Is the notion of 'weight of Earth' meaningless?

I am not talking about the distinction between mass and weight, just the concept of 'weight'. In University physics (book by Young & Freedman, 14th Ed.) it is given that the weight of an object ...
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Variable Mass Intuition

A flat car of mass $m_0$ starts moving to the right due to a constant horizontal force $F$. Sand spills on the flat car from a stationary hopper. The rate of the loading is constant and is equal to $\...
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Difference between monopole moment and charge or mass itself?

I'm trying to understand the difference between monopole moment and charge or mass itself. What I found is related to magnetic monopole that is irrelevant. I want to know in multiple expansion of ...
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If a string had mass in an Atwood machine, would the objects be at rest?

So I understand that the tension produced by a string in an Atwood Machine is constant throughout the string assuming it is ideal, but what if it wasn't? Wouldn't there be a tension gradient, in which ...
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Stress energy pseudotensor of the repulsive gravity of an exotic matter

Postulating the existence of a hypothetical negative mass, would the pseudotensor of its repulsive gravitational field have a negative stress energy? If so, why?
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Calculating the exhaust velocity using conservation of momentum [closed]

I was just wondering if i did this correctly $$p_{exhaust}=-p_{rocket}$$ $$m_{e}v_{e}=-m_{r}v_{r}$$ $$v_{e}=\frac{-m_{r}v_{r}}{m_{e}}$$ I used data from a Saturn V simulation by Robert A. Braeunig ...
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Theta-dependence of QCD quark condensate for $m=0$

I'm trying to understand the $\theta$-dependence of the following expression for the quark condensate in QCD, $$ \langle \bar{\psi}\psi\rangle = - \Sigma \cos(\theta)$$ taken from Eqs. (5) and (7) ...
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What will happen if a body with equal mass of water is submerged in water, will it drown or float?

Suppose I were to take some object that will have a mass that is equal to that of water and I put it in water, will it submerge or float assuming that the object is solid?
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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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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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Is possible to create black hole in laboratory? [duplicate]

Recently I came to know that black hole are the object which concentrate large amount of mass in small volume. what are the requirements to create this if possible?
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Is 'photons being massless' the reason everyone observes their speed to be the same?

When a man on a train throws a ball, the resultant velocity of the ball (as seen from ground) is the sum of the velocity of the train and the velocity imparted to the ball from the throw. However, if ...
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Mathematical model for transition from mass to energy put in layman's terms [closed]

Mass and inertia are interchangeable, but no intuitive explanation of mass being different for the various particles is known to me. The question I have is: since mass and energy are interchangeable, ...
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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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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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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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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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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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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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Why is effective mass a tensor?

So I came across the effective mass concept for solids the other day. It was mentioned that the effective mass is a tensor and may have different values in different directions. However, this is stark ...
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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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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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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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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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Masslessness of the electromagnetic field

Why is the electromagnetic field massless? I presume the mass term in the Lagrangian, $$ \dfrac{1}{2}M^2 A_{\mu}A^{\mu}, $$ would "violate" gauge redundancy. But this is what its name indicates: ...
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Derivation for relationship between rest mass, kinetic energy and momentum

I am trying to find a particle's rest mass in terms of its kinetic energy and momentum. Is this following derivation correct? $(E_{0}+K)^2=E_{0}^2+(pc)^2$ $2E_{0}K=p^2c^2-K^2$ $2m_{0}c^2K=p^2c^2-K^...
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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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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?