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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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Hawking radiation from near horizon

an escape particle carry positive energy cause mass of a black hole is reduced? or a particle into BH carry negative energy cause mass of a black hole is reduced?
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Types of effective masses

I understand the existence of effective mass for electrons, light hole, heavy hole, and split-off. But how can they be different from the density of states effective mass of conduction and valence ...
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How Birkhoff's theorem is applied to the interior of a shell of matter?

Birkhoff's theorem in general relativity states that a spherically symmetric solution to the Einstein's field equations must be static and asymptotically flat. In particular this means that exterior ...
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How can I determine a planet's mass based only off of information about its orbit and its parent star?

I'm coding a video game with procedurally generated planetary systems and I want some and I want to make sure I'm at least somewhat scientifically correct. I've reached the part in my code where I ...
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Where does my mass go when i lose weight? [duplicate]

Presuming conservation of mass to be true, mass has to go somewhere if i lose weight. Doing workout i burn my fat to do some work but then where does that fat go?
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Block in the rain [on hold]

The water is falling horizontally on the masses with speed u, and a constant rate of k kg/sec. When the rain hits the block it drips to the sides. My question is how to deal with the rain dripping to ...
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System's mass and holographic boundary

Can mass map onto a holographic boundary in AdS(or dS)/CFTs? In particular, might the mass of a system vary directly with the surface area of a characteristic holographic boundary? I'm guessing maybe ...
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How big would a black hole have to be to absorb the Sun?

How big would a slow moving black hole have to be to absorb or otherwise destroy the Sun?
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Do black holes have a limit of mass?

If you have a bunch of gas and increase its mass, gravity combines it into a planet. If you have a planet and increase its mass, gravity forces the planet to undergo nuclear fusion, turning it into a ...
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What are Topological mass terms and other doubts [duplicate]

While studying about Cherns-Simons Theory, people use the word "Topological mass terms". Why is it called Topological? Also, explain the origin of mass by taking dual of $F^{\mu v}$ tensor (like in ...
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How do you determine weights from CG when there are more than two locations

On the internet they list ways to calculate weights based on CG when there is a weight on the left and on the right of your CG. Most of the examples show a box truck for determining the weight on the ...
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Determine corner weights of a trapezoid

Working with determining the corner weights on one axis isn't too bad. If A is to the left of the Center of Gravity and B is to the right of the Center of Gravity. You have two equations to work with....
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Does the observable universe lose mass?

As energy is generated from nuclear fusion in all the stars in the universe, does the (observable) universe lose mass in total? How much loss would that be and what is the effect on us (e.g. is there ...
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How is solving Proca equation equivalent to scalar field equation?

My prof. told me that using differential forms proca equation reduces to solving for scalar field equation. How is that? I can’t see how does one relate to Scalar equation using differential forms. ...
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Energy and mass at absolute zero temperature

Hi my question is if the temperature of a particle is reduced to absolute zero the that particle has lost its energy so it has no movement. Particles have mass and Einstein said mass equates to energy....
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Factors of $c$ when giving masses in natural units?

I am starting a course on particle physics, and have been introduced to natural units. I am slightly confused, because we are using 'natural units', and yet masses are stated as, for instance, $139....
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How much of an object's mass behaves as if it is located at the center of gravity? [closed]

We recently finished up a physics lab where a 200g weight was balanced at the end of a ruler on a fulcrum (measuring torque). In the analysis portion of the lab, we are asked: "How much of the mass ...
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Does the gravitational field possess an inertial mass? [duplicate]

I understand that inertial mass, at least in part, comes from the inertia of energy in the zero momentum frame or rest frame of some physical system. So for a static charge the corresponding field ...
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How do we determine who eats who (or which field gets massive) in a Higgs phase transition?

Consider the following theory in which a $2$-form field $B_{\mu\nu}$ with field strength $P_{\alpha\mu\nu}=\partial_{[\alpha}B_{\mu\nu]}$ is coupled to a $3$-form gauge field $C_{\alpha\beta\gamma}$ ...
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If mass can be converted to energy than how is it said that energy can't be created?

From the mass-energy equivalence E=m(c*c), it can be seen that energy can be created and it is not converted from one form of energy. Or am I wrong ? Can you explain?
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Effect of non-zero photon rest mass in optics

If photon has nonzero rest mass, I have inferred that the gauge invariance is broken and the Maxwell's equations change and Klein–Gordon equation comes into picture. What is its effect in optics such ...
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Questioning whether gravity is strictly attractive. Is there a possibility for repulsion?

My teacher wanted to test our understanding before starting a new topic. The question he gave goes something like this “There are 2 vacuums present here about which there is an abundance of mass ...
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Schrodinger equation in momentum representation with position-dependent effective mass

I'm trying to convert Schrodinger equation with position-dependent effective mass (PDEM) to momentum representation, and I'm not sure how to apply the kinetic energy operator. In position ...
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Satellite Motion centripetal force

Once I read in a book that the centripetal force that keeps the satellite in its circular orbit around the Earth is approximately equal to its weight. My question is why the word "approximately" was ...
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Are the so called force balance drawings for motion systems “counterintuitive”?

Lets take the standard mass-spring-damper system with an external force. Please also see the image. As we all know making mistakes with signs in these questions is a common error. There is even an ...
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What are the factors affecting torque (in normal cases)?

I know that force and perpendicular displacement are the factors. I want to know the factors like mass of the body and how and why is the force not distributed throughout the body uniformly. ...
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Is $E=mc^2$ only partially true? [duplicate]

I've obviously seen that $E=mc^2$. But I've also seen that the equation $E^2=(mc^2)^2+(pc)^2$ (where $p$ = momentum) is true. If you square $E=mc^2$, and subtract the result from the other equation, ...
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Rest mass of the photon [closed]

Why is the rest mass of the photon is taken to be zero? If rest mass of the photon is non zero, then it leads to infinite energy of the photon (by $E=mc^2$ equation) and there is a violation of ...
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What is the mass of a volume of air? [closed]

Google says 1 cubic meter of air has 1 kg of mass at room temp. This seems like garbage, as if the container is supplying the mass. But if there is no container, it cannot take 1 kg of pressure to ...
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Are neutrinos just different states of a single particle, in essence?

When Neutrino oscillation phenomenon is analysed quantum mechanically, it is said that, \begin{align} |\nu_e \rangle &= \cos(\theta) | \nu_1 \rangle + \sin(\theta) |\nu_2 \rangle,\\ |\nu_\mu \...
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Is there only one kind of mass of an object in this world?

There are several kind of forces in the world. Is there only one kind of mass of an object in this world? If so, why?
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How force is equal to the product of mass and instantaneous acceleration?

$$\vec{F}=m\vec{a}$$ Suppose that an object of some mass was constantly accelerating ($\vec{a} \neq 0$) through sometime interval. With no doubt, the object had an instantaneous acceleration at any ...
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Mass formula for open string with mixed boundary conditions

I want to give an expression for the mass formula of an open string with has Neumannn condtion in $m$ directions and Dirichlet in $n$ directions $X^{i}(\sigma ^{1}=0)=x_{0}^{i}, X^{i}(\sigma ^{1}=\pi)=...
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Particle collision and mass relation [closed]

Is mass important in calculations when two particles are collide? or is only the charge that matters? is collision in microscopic world the same with macroscopic world?
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$m$ in Klein-Gordon Equation

The Klein-Gordon equation is given by $$ (\square + m^2) \phi(x) = 0 $$ where $\square$ is the d'Alembertian operator, $m \in \mathbb{R}$ and $\phi$ is a scalar field. Question: What is $m$ in the ...
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How is mass related to the Poincare group?

I have studied about Poincaré group and some QFT, read that the Casimir elements are $p^{u}p_{u} = m^2$ and Pauli-Lubanski vector (or pseudovector). How does the mass come into picture and spin come ...
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Why is it doubtful that higgs field gives neutrino mass?

I read some articles mostly claiming that if neutrino is their own antimatter than they could get their mass from some other source rather than the higgs field, and I can't probe any further because ...
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How can mass flux be defined for a one-dimensional flow?

I am reading a textbook where an example of a one-dimensional binary diffusion is given. In a binary system composed of substances A and B, we write a relation for the substance A: $\dot{m}_A'' = Y_A(...
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Alternative particle types?

If we consider mass and charge to be excitations of independent quantum fields, do they necessarily travel together? Can we have objects with only an excitation on the mass field, and objects with ...
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Schwarzschild geometry for negative masses

Imagine that in a part of our universe there exists negative masses $M=-|M|<0$. The metric around this object -- say a black hole -- will be of the form $$ ds^2 = -\Big(1+\frac{2|M|}{r}\Big)dt^2 + ...
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Weight of an object without air

Consider a weigh machine and an object. Both are inside a case. Weigh the object. Then remove all the air in the case. Weigh the object again. If the weight of the object with air is M kg. What will ...
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If photons have no mass, why do they gain mass in photon entanglement?

Photons are massless particles. However, this article states that photons can gain mass when they become entangled. How can this happen? From the article: Physicists create new form of light ...
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What gives mass to black hole?

I like to know when a dying star collapsed into a black hole, is there anything inside or on the event horizon that is interacting with higgs field?
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Why is torque sometimes reported in kg m, instead of the usual N m?

On various websites I see torque expressed as $\rm kg\: m$, but I was always thought that torque is $\rm N\:m$ or $\rm kg\: m^2/s^2$. These are clearly not the same, so why are they called the same, ...
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What would a universe with a long range weak force look like?

If the W's and Z bosons were massless at low energies (i.e. no Higgs interaction), what would the universe look like? Would there be "weak bound states" ? How would electromagnetic theory differ with ...
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Do higgs field affect rest mass and relativistic mass? [duplicate]

I know most of the "mass" comes from the binding energy such as gluon but suppose I apply a force on a matter particle, do I change the interaction between the particle and the higgs field? How does ...
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If negative mass should exist, how would conservation of momentum work?

Imagine that a particle with negative mass has been discovered. It is known to obey both the equivalence principle and Newton's second law. This means that the particle is a subject to repulsive ...
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Is there a mass spectrometer software that can measure the mass of a hydrogen atom [duplicate]

For a school project I need to measure the mass of a hydrogen atom either as a lab experiment or with a computer simulation. Since I don't have the appropriate equipment for the experiment, does ...
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Does a field gain energy or does the mass/charge?

My textbook reads that when a mass/ charge is moved into the influence of a gravitational/ electric field the field gains/ loses energy rather than the mass/ charge. How can this be explained?
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A fundamental question about charge and speed of a particle [duplicate]

Hi everybody and happy 2019. In my teaching sessions sometimes someone asks questions i cannot truly answer (although i have many arguments on it) and here's one that really puzzles me: A massless (...