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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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Farnes, cosmology involving negative mass

I came across a paper recently which seems to be getting a lot of popular press, and a student also emailed me to ask about it: -- Farnes, "A Unifying Theory of Dark Energy and Dark Matter: Negative ...
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Where do gravitational waves and general relativity coincide? [on hold]

In the first ten seconds of this video (https://www.youtube.com/watch?v=iphcyNWFD10) the host says that gravitational waves were the result of two black holes merging. That would seem like there is ...
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Couldn't we always redefine units so that inertial mass and gravitational mass are equal?

It is a known fact that inertial and gravitational masses are the same thing, and therefore are numerically equal. This is not an obvious thing, since there are even experiments trying to find a ...
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Why we can know what flavor the neutrino is created but not their mass? [duplicate]

All neutrino knows which of the 3 flavours they must be upon their creation, however their mass becomes uncertain... why is that? isn't mass supposed to tie to which ever flavours like for example an ...
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Do vibrations increase an object's mass or weight?

does a vibrating object recieve an increase of mass or weight? and if it does, at what frequency or intensity does it need to vibrate at, and what is the rate of increase? is there a formula for it? ...
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Mass versus rotation Curves

Is there an equation that describes the relationship between the mass of the Galaxy and rotation curve? I found V versus R graphs and equations that describe their relationship (kind of). But I ...
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Do the weights of two liquids not add when mixed?

I was given an interesting dilemma today. A co-worker saw me adding a liquid (Diisopropyl ethylamine AKA DIPEA) to a flask filled with another liquid (Tetrahydrofuran AKA THF). I needed to weigh out ...
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Can we weight dark matter?

We can observe the effect of light as it gets bended in the presence of dark matter, and I wonder how is it possible to measure their mass given that we can't see them and they don't interact with ...
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You find your mass to be less that 42kg on a weighing machine. Is your mass more or less than 42kg? [closed]

I have this question in which I'm really confused. Initially, $F=ma$. this means that mass is obviously less than weight. So,the mass will be less than 42kg. But on the other hand, we know that mass ...
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Is the barycenter always at the same position?

I am currently preoccupied with the Two Body Problem and I was wondering whether the barycenter, or center of mass, is a static point or if it is moving, and how to calculate its position.
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Relativistic Mass when Viewed from Different Frames of Reference

I understand relativistic mass and the equations underpinning it. My question deals with how to calculate relativistic mass when an object is viewed from different frames of reference. Consider a ...
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Work-Energy Theorem for Non-Constant Mass

"The net work done on an object is equal to its change in kinetic energy." Let's say that a rocket is moving upwards while expelling gas and is thus losing mass. (Non-constant mass) As the object ...
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What is the physical meaning of the trace-free part of the second fundamental form?

Given a submanifold $X$, the second fundamental form tells you about how the submanifold is embedded in the ambient space (intuitively by measuring how a normal vector field varies from point to point....
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How are these two definitions of energy related/derive from each other? [closed]

How are these two definitions of energy related/derive from each other: $$E = \frac{mc^2} {\sqrt{(1 - v^2/c^2)}}$$ vs. $$E = \sqrt{m^2c^4 + p^2c^2}~?$$ Both equations express the relation between ...
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What is meant in mass' definition 'resistance to acceleration'? [closed]

Wikipedia: Mass is both a property of a physical body and a measure of its resistance to acceleration What does this mean? I know of the $E=mc^2$ formula. I think, the energy required to '...
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Why are the volumes above and below the center of mass of a uniform cone not the same?

So today in my physics class we derived the center of mass of a uniform cone, and it all made sense, but near the end of class a student asked, "If you were to split an object into two parts with ...
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Negative Mass and Gravitation vs. Inertia

Recently an article came out about an interesting result in cosmology that somehow "unifies" dark matter and dark energy. It talks about a "creation" tensor that describes negative mass appearing ...
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What is more massive, Proton, standard Hydrogen?

If you consider the classical states of hydrogen, one in which the electron is rotating at an orbital distance of $r$ and then take $\lim_{r\to\infty}$ one obtains that the $r_\infty$ state has more ...
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see-saw centre of mass but with upward forces

Am trying to find how far the centre of mass is skewed from the central distance point. The part I'm unable to grasp here is that I'm working with forces which also push the see-saw upwards (anti-...
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Can the mass of a hydrogen atom be calculated in a gauge-invariant way?

Please excuse the lengthy question. It involves an interesting controversy which has arisen in discussions on this site: Energy/mass of Quantum Vacuum Relative potential energy vs Absolute potential ...
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Is the relativistic increase in (relativistic) mass same for a freely falling body as compared to body which is accelerated to the same velocity?

For a similar mass either falling toward a black hole or accelerated by a force is there a comparable increase in mass for similar velocity? Suppose a mass of one kilogram is accelerated to 99% of the ...
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Does the death of Kilogram ($kg$) affect us in any means in our day to day life? [closed]

Recently, the sleek cylinder of platinum-iridium metal has been discarded and the kilogram is set to be redefined along with ampere for electricity and Kelvin for temperature. Hereafter the Kilogram ...
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Why the photon doesn't acquire mass with the Higgs mechanism?

I did the computation that from $$(0,v)^{T}(\partial_\mu+igA_\mu^a\tau^a+i\frac{g'}{2}B_\mu)(\partial_\mu-igA_\mu^b\tau^b-i\frac{g'}{2}B_\mu)(0,v)$$ with $(0,v)$ being the expectation value of the ...
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How does inertia work at the particle level?

I've read recently that the mass of a proton is mostly not given by the Higgs mechanism. But rather it's given by the energy of quarks moving around inside the proton and gluons and other internal ...
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D'Alembert's principle when the mass of the particles are changing

In the book of Classical Mechanics by Goldstein, at page 19, while deriving D'Alembert's principle, the author assumes that $$\dot p = m \ddot r.$$ However, when the mass of the bodies also changes, ...
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The strong CP problem in Grand Unified Theories

The strong CP problem could, in principle, be solved by a massless up quark. Can this solution be embedded in Grand Unified Theories, such as $SO(10)$ (or $SU(5)$)? These theories, in particular $SO(...
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Energy/mass of Quantum Vacuum

So far as we have measured the volume of the universe, has anyone calculated the virtual energy/mass of the Quantum Vacuum? If so, what? Or if not, a local volume such as 1 sq. meter? This relates to ...
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Why is $E=mc^2$ and not $E=m\frac{c^2}{2}$?

Kinetic energy for a moving object is the integral of force with respect to distance, often given as: $$E=m\frac{v^2}{2}.$$ This would imply that for mass moving at the speed of light, the kinetic ...
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Fluid mechanics

i have seen the following equation of continuity for fluid dynamics for compressible as well as incompressible fluids $\rho_1V_1A_1 = \rho_2V_2A_2$ and it is derived from conservation of mass ...
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Why mass has no effect on free-fall acceleration? [duplicate]

I learned that mass is a property of objects that specifies how much resistance an object exhibits to accelerate. So, pushing an object with a greater mass would cause a smaller acceleration than ...
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What is the mass of $N_A$ atoms of carbon-12?

With the recent redefinition of the kilogram, what is the mass of $N_A$ (Avogadro's constant) of carbon-12 atoms? $N_A$ was defined as exactly 6.02214076×$10^{23}$ atoms. Then how close would the ...
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How massive is the Sun compared to other stars?

I was just reading "Rare Earth" by Peter Ward and Donald Brownlee and they claim that $95\%$ of stars are less massive than the Sun. But, I was always told the Sun is an average star. Which is it?
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Double pendulum centre of mass

I have a question regarding the double pendulum problem. I know that the centre of mass of a system does not move if any external forces are applied to the system. For example, when you throw a chain ...
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Does relativistic mass really increase with velocity? [closed]

Suppose there are two masses on the ground $M$ and $m$. The distance is $d$. So according to newton's law the gravitational force between them is $F=\frac{GMm}{d^2}$. Now suppose that I am going ...
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Black Hole Surface Area-Mass Equation

Lets suppose we have a BH with mass $M$ and surface area $A$. From the Schwarzschild raidus we can say that the Area of the BH is proportional to its mass $$A=4\pi r^2=\frac {16 \pi G^2M^2} {c^4}$$ ...
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How is a Kibble balance used in the new definition of the kilogram, and what's the connection between the balance and Planck's constant? [duplicate]

The BBC News article Kilogram gets a new definition says: How does the new system work? Electromagnets generate a force. Scrap-yards use them on cranes to lift and move large metal objects, ...
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What will happen to the International Prototype Kilogram? [closed]

The kilogram has been redefined in a way that does not refer to the International Prototype Kilogram. That kind of makes the International Prototype Kilogram useless. So what will happen to it? Can I ...
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A new definition of mass using Planck constant

Tonight in a italian television news channel well known internationally I have heard that almost certainly the definition of mass that we currently know will be obtained by means of the constant ...
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Binding Energy and Energy Mass Equivalence

Consider a neutral atom. An external force acts on one of its valence electron so that it brings this valence electron to infinity away from the rest of the atom. The electron's kinetic energy does ...
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Is Higgs mechanism generate mass parameter? Or physical mass?

Is Higgs mechanism generate mass parameter in the Lagrangian? Or physical mass that we can observe in experiment? It is obscure for me how Higgs mechanism produce mass for elementary particle. ...
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Conservation of mass in relativistic collisions?

It's stated in my textbook that relativistic mass is conserved in collisions, even in inelastic ones. So if you have a particle with rest mass $m$ moving with speed $u$ (considerable fraction of the ...
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How is the acceleration proportional to the net force over the mass? [closed]

The acceleration is inversely proportional to the mass when the force is constant. Also, the acceleration is proportional to the force when the mass is constant. So, how can the acceleration be ...
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Do the inertial mass and gravitational mass of an object depend on the frame of reference?

My understanding is that the "relativistic mass" of an object means any of the following three quantities (which are all identical): The "mass-energy", as defined by the formula $m = E / c^2$. The ...
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$\rm kg$ is to symbol, as kilogram is to unit as mass is to what?

I'm sure this has a very obvious answer but I can't even work out how to properly phrase the question. How do you collectively define what mass, temperature, and area actually are? For example, $\rm ...
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1answer
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Pulling of Light by a Black Hole? [duplicate]

We all know that light has no mass at all. Yet we say that the gravitational pull of a Blackhole within Schwarzschild radius doesn't let light to pass. If the light has no mass, how can it experience ...
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Is the electroweak $SU(2)$ gauge symmetry an exact symmetry in Standard Model before spontaneous symmetry breaking?

In Standard model, components of a $SU(2)$ doublet (for example $u$ and $d$) have different masses. This means there is no $SU(2)$ symmetry, but I think it is okay because the $SU(2)$ symmetry is ...
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How can I calculate the chemical potential and the effective masses in an intrinsic semiconductor?

I want to calculate the chemical potential and the effective masses of the germanium charge carriers considering that the relaxation time is the same for the two carriers: electrons and holes. ...
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Particle simulation: understanding mass

I'm trying to understand how mass factors into forces acting on particles in a simulation. For the sake of argument, imagine a 1-dimensional simulation of a particle, whose position is 0 on the x-...
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If photons don't experience time, does that mean time is a consequence of mass? [closed]

If photons don't experience the passage of time because they have no mass, does that mean time is a consequence of mass? To me that's a profound conclusion yet not one I see printed. Is it right?
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Quantum mechanics problem about Bound states

Show that for a particle in the ground state in one dimension, the bound state energy decreases as mass increases. Also potential at infinities is 0 I used all the machinery I know. I think the ...