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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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Hierarchy problems: calculating the mass of the Higgs vs. other SM particles

While reading up on hierarchy problems in particle physics (wikipedia), I stumbled onto the statement that in the Standard Model, there is no hierarchy problem (or at least it cannot be formulated) ...
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How to derive: $\frac{E^2}{c^4} = \frac{p^2}{c^2} + m_0^2$?

My teacher wrote the following equation on the board a few days ago: $$\frac{E^2}{c^4} = \frac{p^2}{c^2} + m_0^2$$ And I got no idea how this is derived especially since we already derived that: $$m^...
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Does the universe have a fixed centre of mass?

Does the universe have a fixed centre of mass? If it does, doesn't it necessarily mean that every action of ours has to be balanced by a counteraction somewhere in the universe so as to neutralize the ...
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How much of the proton's mass is due to the Higgs field?

The proton mass is 938 MeV. People often claim that (A) The proton is a bound state of two up quarks and one down quark, with the three quarks contributing a total rest mass of $2 \times (2.2 \text{...
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If you could bottle a photon would it have mass? [duplicate]

Ok. A photon has no rest mass for the good reason that it has no rest energy. But what about a standing wave? There is fair belief that particles are standing waves, so perhaps nothing rests. So. ...
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How is weight dispersed among multiple points?

I was recently viewing remembrance photos from the 1995 bombing of the Alfred P. Murrah Federal Building on MSN news where slide nine shows a photo of firemen teaming up to carry a $40'$ steel bar ...
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Why does a heavier element have a low specific heat capacity?

Lead has 207 amu and 125j/kg/c while copper has 63 amu and 376 j/kg/c, why is that? So if energy is stored in the motion of the particles, heavier particles should move slower and therefore wouldn't ...
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Composite objects, mass, and internal energy in relativity

Why do we define the free Hamiltonian of composite particles as $$H_0 = \sqrt{M(t)^2c^4 + P^2c^2}$$ with $M(t)\neq\sum_im_i$ instead $$H_0 = \sqrt{M^2c^4 + P^2c^2} + U(t)$$ with $M=\sum_im_i$ and $...
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Force required to propel mass in vacuum [on hold]

I'm not mathematically inclined. At. All. I'm a massage therapist and mental health provider. I am, however, writing a book that takes place in space. My main character (MC) is 4'11" and weighs 95#/~...
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Does infalling material leaves a detectable imprint on the black hole's event horizon?

An external observer will never see anything cross the event horizon, and in most explanations the story ends here. But I wonder what happens with gravitational effects of the material? For example ...
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Would equal balance at same height when hung on a balance?

This is based on a question from the gravitation course on Brilliant. As you can see in the diagram below, we have 2 weights hung on a pulley. It is given that: Neither one accelerates when you let ...
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Are Instantons Massless?

That is, are the only field configurations which give a non-zero winding number ones in which the Fourier transform includes a factor like $\theta(k^0)\hat{D}\delta(k^2)$, where $\hat{D}$ is some ...
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What is the relativistic mass of Red Light? [duplicate]

After using all the equation and formula's I am getting Light has a certain mass, i.e. 3.157x10^-36 (approx) Kg. Then I have calculated the Energy by using the famous equation, i.e. the E=mC^2 (In ...
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How we can prove that photons have no mass? [duplicate]

I am thinking nowadays that how its possible that a particle without mass, actually exists? in the case of light its used to say that photons have no mass no weight but they have momentum. can any ...
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If inertial mass changed as a gravitational field changed would we definitely realise

It strikes me that matter can only directly interact with another bit of matter when its in an identical gravitational field. This makes me wonder whether if inertial mass increased and decreased with ...
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Meaning of $M$ in Schwarzschild metric

In the Schwarzschild metric $$ds^2 = - \left(1-\frac{2M}{r} \right) dt^2 + \frac{dr^2}{1-\frac{2M}{r} }+ r^2 d\Omega^2. $$ Is it safe to call $M$ the mass of the source of curvature? Or should I ...
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Springs with some finite mass

Let us consider a spring which is having some finite mass. By the help of some external agent the spring has been extended by some distance $x$. Will the restoring force produced in the spring still ...
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Why is gravity the weakest force if, theoretically, it is made up of all the other forces' fields?

I'm quite new to the physics world and want to get an idea as to how physicists have been able to sum all fields/forces (higgs boson, electromagnetic, weak force, strong force etc) in a said object, ...
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Is this relativistic mass?

I have seen in a lot of places in here clearly stating that relativistic mass is outdated, that we can make do just fine with the concept of invariant mass,etc. But I've also seen people saying that a ...
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Decay width of the tau lepton

The total decay width of a particle, $\Gamma$, is proportional to the fifth power of its mass, $m$, $$ \Gamma \propto m^5$$ We also know that the dominant decays of the tau lepton are $$\tau^- \to \...
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Is there an example of two elementary particles colliding to result in a single elementary particle?

Apologies for the novice question, but I don't know enough particle physics to immediately answer my own questions. I have the following questions. Is there an example of an inelastic collision ...
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Minkowski space

In Minkowski space, coordinates which satisfy $x^2 = t^2 - X^2 > 0$ are in the region of spacetime that is time-like. If it's $x^2 = t^2 - X^2 < 0$ the region is space-like. But if $x^2 = ...
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Equivalence principle before Einstein [migrated]

In a German interview some physicists were asked, what they would ask Einstein, if he were alive today. One of them wanted to know how Einstein came up with the idea of the equivalence principle, that ...
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Does the work-energy theorem assume that the particles of the system have time-independent masses?

$\newcommand{\force}{\mathbf{F}}$ $\newcommand{\velocity}{\mathbf{v}}$ $\newcommand{\position}{\mathbf{r}}$ Here's an incomplete proof of the work-energy theorem: $$W = \int_1^2\force \cdot d\...
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Are energy and mass two forms of the same thing?

I know that energy can convert to mass and vice versa. So are we not looking at simply two forms of the same thing?
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Change of entropy of mixing in terms mass ratio

I am stuck on this problem. Suppose we are mixing substances $a$ and $b$, we have $$\Delta S_{mixing} = -Rn_a \ln (\frac{n_a}{n_a + n_b})-Rn_b \ln (\frac{n_b}{n_a + n_b})$$ and we are told to ...
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Gravity and Newton's Second Law of Motion [duplicate]

So we were learning about Newton's 3 Laws of Motion and I had a question about the second law and gravity. Newton's 2nd law shows that, with a constant force, if an object has a greater mass, it will ...
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Why does four-momentum have to be tangent to the worldine?

In relativity, we define momentum for a particle as a vector that is always tangent to the particle's worldline. I am wondering what is the exact reason this is necessary. For a massive particle of ...
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If a black hole is created from light, can this black hole then move at the speed of light?

Imagine we managed to squeeze light into a very tiny region of space so that the energy concentration at that point becomes a black hole. Can this black hole then move at the speed of light?
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Why do we say that a photon is a particle if it is massless?

If light is made of photon particles and the photon doesn't have any mass but it is a form of energy (according to my thinking) then why do we call photons particles?
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Force and center of mass acceleration

https://i.stack.imgur.com/3w7Mt.png I have a rod with mass $m$. Above are two ways I can apply a perpendicular force to the rod. Since the mass of the rod is uniform, its center of mass is in the ...
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How much force is needed to move a 70kg person?

I have a science question to answer, and just need some things cleared up. The question states: 'If a sprinter starts out of the blocks and speeds up to reach a top speed of 15m/s in 5 seconds, what ...
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If an object with more mass experiences a greater gravitational force, why don't more massive objects fall faster? [duplicate]

According to Sir Isaac Newton, the gravity equation runs like this: $$ F = \frac{Gm_1m_2}{r^2} $$ where $F$ is the gravitational force, $G$ the gravitational constant, $m_1$ and $m_2$ are the ...
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Does the expansion of the universe explain why the universe doesn't collapse?

Notes: 1. I'm in 8th grade so i don't have in-depth schooling on this. Lengthier explanations with more extra information that would improve understanding would be much appreciated. 2. I asked a ...
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Can a Spaceship decelerate by increasing its mass?

Suppose the following thought experiment: A spaceship travels at speed u and has mass m. At a point, it converts massless or low mass particles, that it "carries", to heavier particles without any ...
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QCD Trace Anomaly and Mass

In the paper in equations 4 and 5, some of the mass of the nucleons comes from the "trace anomaly" of the QCD energy-momentum tensor (as described in the paragraph following these equations). Is there ...
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Hawking radiation and mass annihilation [duplicate]

Now, i just heard that the particle anti particle pairs that zip in and out of existence every planck second both have positive mass. if that is so, how does hawking radiation work? black holes lose ...
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Why does mass cause resistance to acceleration?

If I were in a vacuum with no gravity or friction, why would it be harder to push a floating bowling ball than a marble? Is there anything happening on an subatomic level that makes matter act ...
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Why do we believe local gauge invariance (that tells us photons are exactly massless)? [duplicate]

There are experimental upper limits on the photon's mass, but they are finite. I heard that the reason we know that photons have exactly zero rest mass (and thus travel exactly at the universal ...
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Finding 3 unknowns in 2D-collision problem [closed]

While solving a 2D-collision problem, I obtained the following 3 equations: $$0.866\,|\vec v_{Af}|+|\vec v_{Bf}| \cos \theta_{Bf}=6$$ $$0.5\,|\vec v_{Af}|+|\vec v_{Bf}| \sin \theta_{Bf}=0$$ $$|\vec v_{...
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Invariant mass in special relativity [closed]

I'm following a special relativity course and I'm trying to understand how the invariant mass works. In particular I don't get how the following passages work. We have a collision between two ...
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Derivation of Komar formulae from ADM formalism?

Is there a way to derive the Komar formulae from the ADM formulae? Both the formulae give the same answer for mass and angular momentum, so I was wondering if one can be derived from another. On an ...
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How to calculate the mass of gas needed to fill a cylinder to a certain pressure?

I m tasked with a tricky situation. I need to calculate the exact amount a tank can take in gas. But I dont know the volume of the tank. I just need to make sure that the tank reaches the right ...
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How does the mass distribution and center of gravity affect the speed of a lego car down a ramp? [closed]

we are doing a research involving motion of an object with a nonuniform mass distribution, and we have to explain how mass concentration, mass distribution, and center of gravity will affect a Lego ...
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Why is the proton (uud) lighter than the $Δ^0$ (uud) baryon?

Neutron has quark composition udd with spin $\frac 12$. $\Delta^0$ baryon has quark composition udd with spin $3 \over 2$. On Wikipedia it says that $\Delta$ baryons have mass of approximately $1232 ...
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Do photons have any relativistic mass?

In some books I found they are writing photon momentum $mc$ rather than $E/c $. Which one is right? But if I put $v=c$ in relativistic mass equation, $$m=\frac{m_0}{\sqrt{1-v^2/c^2}},$$ it becomes ...
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Force during collision would be very high, would it cause a very big damage? [closed]

So suppose a body of mass 10kg travelling at 5m/s crashes into a wall, the time of deceleration would be very minute, say 0.01 second, then the magnitude of deceleration would be $$\frac {0-5}{0.01} ...
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How similarly are light and matter affected by gravity?

For a path of travel in a shape that is straight before it curves, if the curvature of the path is attributable to gravitational force, what additional information (if any) would be capable of ...
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Special relativity - mass energy and momentum [closed]

I've just started studying relativity and I think I have just about gotten my head around time dilation and length contraction and I have now been able to derive the two equations $$t=\frac{t_0}{\...
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Relativistic mass

I've always seen older books talking about relativistic mass all over their special relativity introduction $m=\gamma m_0$. But I can't stand it. It makes no sense to define this quantity at all. To ...