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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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Is mass equivalent to potential energy? [on hold]

In other words, do we really need the concept of mass? If so, why?
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109 views

Renormalized mass

I am reading Schwarz QFT and I reached the mass renormalization part. So he introduces, after renormalization, a physical mass, defined as the pole of the renormalized propagator, and a renormalized ...
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3answers
73 views

According to general relativity, why are two objects at rest attracted to each other? [duplicate]

I'm trying to understand gravity in General Relativity and I'm having some questions. I can understand that an object in orbit around another more massive object is free falling and simply following a ...
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1answer
64 views

Why photons do not have mass? [duplicate]

According to Einstein $E= mc^2$ so $m = E/ c^2$. So energy present in an atom contributes to its mass. So if a photon is a carrier of energy shouldn't it have mass since energy contributes to mass of ...
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Derivation of pressure gradient stellar equation [duplicate]

I am trying to understand how to derive the following formula: $\frac{dP(r)}{dr}=-\frac{GM(r_<)\rho(r)}{r^2}$ The notes are as follow: Consider a star with COM and a shell: $P_1 - P_2 = -{\...
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3answers
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Would a shaken up bottle of soda weigh more than a unshaken one?

I asked this question on a different physics forum and some cited conservation of matter, but some others didn't know whether it would be applicable in this instance. So I thought I would ask the ...
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Why Gravity doesn't affect Horizontal acceleration/motion?

It is still hard for me to grasp on why gravity doesn't affect horizontal motion, doesnt gravity causes a change in resultant force and thus cause a change in acceleration $F=m.a$
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Were passive and active gravitational mass actually ever considered to be different? If yes, why?

Mass produces gravity and is subject to it. It seems impossible to separate the two phenomena and the equivalence of the two forces was stated centuries ago. Wiki considers measuring two different ...
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Why do lighter pendulums come to rest faster than heavier ones?

I've been reading this website, which stated: All pendulums eventually come to rest with the lighter ones coming to rest faster. I have been taught the mass of a pendulum does not affect its ...
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Does a person moving at almost the speed of light observe their own mass increasing? [duplicate]

Firstly I'm not a physicist/not formally studying the subject, but I do have an increasing interest in the subject. I understand from the Lorentz formulas that mass increases relativistically, but if ...
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1answer
70 views

Can the mass term be responsible for creation and destruction of particles?

In an interacting quantum field theory, for example, QED, the Dirac mass $m\bar{\psi}\psi$ is a piece of the free Dirac Lagrangian. On the other hand, the interaction term $j^\mu A_\mu=e\bar{\psi}\...
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Does infinite mass exist? [closed]

So when I search up if infinite mass exists, google provides me with a source that states infinite relativistic mass does exist at the speed of light which is why it is impossible to ever reach to ...
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1answer
34 views

Issue in conversions from force to mass units

I have a problem converting force to mass units, in this example for 9.81kgf: To get the mass, dividing by gravity, I get 1kg ...
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1answer
55 views

Conversion between mass units

I am enrolled in a course related to physics, and converting between mass units is so tricky for me. I always treat in my work only in SI units and maybe MKS units, at level of weights, I find it easy....
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1answer
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I couldn't figure out something about mass and weight measurement

Today when I was studying physic for my University enterance exam I have stucked in one topic. I understood the difference between mass and weight. Mass is the amount of material an object contains ...
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What does infinite-mass limit mean in the context of Effective Field Theory (EFT)?

I came across this term in section 2.1 of the paper Weak Gravity Conjecture From Low Energy Observers’ Perspective. 2.1 Heavy Particle Effective Theory (HPET) ... The starting idea for ...
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3answers
59 views

Which frame of reference is used for rest mass calculation?

If there are no special reference frames or absolute rest frames, then rest mass of, say electron, is defined with respect to which frame? Why cannot such a frame be used as the absolute rest frame?
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1answer
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What are significant applications of the Higgs Boson itself in the standard model?

I understand that the Higgs Field grants mass to all the matter in the universe, and is equally distributed in all parts of it, but it was the Higgs Boson that was discovered at the LHC, and ...
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4answers
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Energy vs. mass in photons

I am confused about the following: Mass is condensed energy. A photon has no mass, but it has a degree (of quantised) energy. Does that mean it does not have enough energy for it to be condensed ...
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The relation between mass, inertia and energy

I have trouble understanding the following concept: I learnt that mass is a measure of inertia, and that seemed logical enough. Yet separately I learnt that mass is a form of condensed energy. If ...
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2answers
111 views

What is meant by the absolute scale of the neutrino mass?

In this review titled "Pieces of the Flavour Puzzle" the author Ferruccio Feruglio wrote in the introduction that "The origin of the parameters in the flavour sector of the Standard Model (SM), ...
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1answer
45 views

Relativistic mass of photon [duplicate]

What is the relativistic mass of one photon, i.e. what is $N$ here: $10^{-N}$ kg?
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2answers
50 views

Innermost stable circular orbit in Schwarzschild solution

I've been reading about GR recently and I can follow the derivation of a Schwarzschild solution to it's final and well known form in Schwarzschild coordinates. The orbit stability argument (for a ...
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5answers
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Distinction between various forms of relativistic energy

If I am told to find the total relativistic energy of a particle moving with some velocity v, do I use $E=\gamma mc^2$ or $E^2=p^2c^2+m^2c^4$ and take the square root. I am not sure the distinction ...
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Why can’t we accelerate photons, and is it possible for a photon to have mass? [duplicate]

So I’m doing a science project and I’m trying to understand why the photon is massless. I’ve learned that neutrinos were thought to be massless at first, but then physicists found 3 types of neutrinos ...
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1answer
34 views

Need help creating an equation for the time it takes for a rocket to deaccelerate (accounting for fuel mass lost)

I'm doing a Math Internal Assesment for school where I'm trying to create a model for a rocket's suicide burn. I've gotten stuck in one of the equations I need for it. I need to find the time it would ...
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2answers
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Does light have a non-zero mass? [duplicate]

I heard that the light has zero mass. But I searched in internet, some people say light has mass and some people said doesn't. I am not sure what is the right answer. And also I heard that the reason ...
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1answer
64 views

What is the real definition of density? [closed]

What does density really mean? Everyone just provides me with the equation of finding density whenever I ask this question.
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3answers
2k views

Can the center of charge and center of mass of an electron differ in quantum mechanics?

Traditionally for a free electron, we presume the expectation of its location (place of the center of mass) and the center of charge at the same place. Although this seemed to be reasonable for a ...
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1answer
55 views

Is quantum physics a reason for the measurement differences of the International Prototype Kilogram

I've recently learned that there is an official Kilogram (IPK) kept in Paris which is used to calibrate, directly or indirectly, all weight measurement tools. I've also learned that each time the IPK ...
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2answers
95 views

How did Newton know that there is force between two mass? [duplicate]

Newton's Law of Gravitation states: $$F=\frac{GM_1M_2}{r^2}$$ How did he recognize that there is a force between two masses?
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1answer
55 views

Effect of mass on gas pressure

I know that PV=nRT and this equation does not take mass into consideration. However P is also =Force/Area. And weight is a force which is equal to mg. Will gas pressure be dependent on the mass of ...
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1answer
99 views

Is it possible to create weighing machine with water indicator [closed]

I want to create a weighing machine that works with water. After researching on Google I got this. $1$ $\text{cm}^3$ of water weights $1$ g. So, with that equation I'm planned to create this below ...
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3answers
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Actual mass and Apparent mass due to Force

Suppose a block is placed on a surface (with a non-negligible frictional constant) and a person exerts a constant force $F_1$ on it parallel to the surface. Whether the force is able to cause ...
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2answers
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Relationship between acceleration due to gravity and mass [closed]

See http://www.feynmanlectures.caltech.edu/I_07.html: "This statement can be expressed mathematically by the equation [...] If to this we add the fact that an object responds to a force by ...
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1answer
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Mass (as a unit) has no physical property [closed]

Einstein's GR or Newton's equation uses mass as unit or number. How can it cause gravity (physical phenomena)? For any physical phenomena to occur, there must be physical/chemical/biological/etc. ...
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2answers
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Commercially available material with highest density to cost ratio? [closed]

What are the top 5 commercially available materials (not limited to just the elements) with the highest density to cost ratio? To point to an application, say that my goal was to mass produce a solid ...
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1answer
19 views

Does the weight of a spinning gyroscope change how much weight it can sustain (stabilize)

Hello I recently watched a video about gyroscopes and I wonder what changes the amount of mass it can keep upright. EDIT: I did search online but I couldn't find a website which explains this in a ...
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0answers
60 views

Helicity: massive vs massless particles

Usually massive particles can be described as eigenstates $|p,\lambda\rangle$ of the angular $J^3$ operator, while massless particles are eigenstates $|p (m=0),\lambda\rangle$ of the helicity operator ...
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What happened to particles travelling at light speed at the instant the Higgs ocean formed?

Reading the Fabric of the Cosmos (Brian Greene) where he mentions, during the big bang, the Higgs field was undergoing fluctuations at a temperature too high to form the Higgs ocean. It implies that ...
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0answers
55 views

Why are there no loop corrections to the photon mass? [duplicate]

I know that a question about why the photon is massless already exists, however it did not answer this question. First off, I do understand why the photon does neither have a bare mass term due to ...
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1answer
91 views

relativity: accelerating a flywheel

Let's say we have a pair of flywheels rotating in opposite directions and they're inside a black box so that maybe we don't know that's what's inside, and we accelerate the box in the direction of ...
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1answer
38 views

How to calculate the mass-matrix for a Lagrangian with $SO(3)$ and $SU(2)$ symmetry?

Consider a Lagrangian: $$\mathcal{L}=\frac{1}{2}\partial_\mu\phi_i\partial^\mu\phi_i - V(\phi);\\V(\phi)=-\frac{1}{2}\mu^2\phi_i\phi_i+\frac{1}{4}\lambda\phi_i\phi_i\phi_j\phi_j.$$ I understand that ...
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2answers
32 views

Weight distribution's effect on riding uphill

Two different chains of cars (attached to each in a row) are driving uphill (Only the first car is motorized): The first chain consists of 3 cars, each 4000 kg. The second chain consists of 3 cars, ...
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2answers
160 views

Mass of the electron

In the classical limit, three quarters of the mass-energy of the electron come from the energy of the electromagnetic field of its charge (see Electromagnetic Mass). Intuitively one would expect that ...
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1answer
138 views

Why is tension in a rope the same at every point?

So, I had this lecture where it was explained that if the pulley is friction-less, then the tension on any point of the rope is going to be same. I can understand the friction-less part, as pulley is ...
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1answer
80 views

Near-relativistic car speeding over a bridge

I have read this problem / exercise (I don't remember the exact numbers, so I put my own) in William Burke's "Applied Differential Geometry" and it has always puzzled me regarding the relation between ...
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3answers
140 views

Difference between Mass and Inertia

My questions is about mass and Inertia, what is the difference between Mass and Inertia? Are they the same or different? How? I am really confused with it,some says mass is the measure of Inertia, ...
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0answers
61 views

Is Relativistic Mass for real? [duplicate]

Is relativistic mass real or is it just a convenient mathematical concept? Is there actual increase in the physical mass of an object when it travels at a speed > 0. What I mean is that from a physics ...
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3answers
107 views

Is there a chance for moon to collide with earth?

I have learned that attraction between the bodies increases when it's mass increases ,if the population increases day by day and hence it can increase the mass of earth which causes attraction ...