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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3
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2answers
333 views

Determination of mass density distribution of an object

This is a follow-up to a previous question How can you weigh your own head in an accurate way?. My purpose is not to restart the flurry of more or less humorous jokes (which are not such a bad thing ...
0
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1answer
121 views

why is mass of air bubble in material medium considered to be negative?

The mass of air bubble in any medium is considered as negative. Is the air bubble is massless. I m in confusion. can we not neglect the mass of air bubble in material medium. But i have found in many ...
-3
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1answer
193 views

String theory and the SM spectrum [closed]

Long ago, I realized this: (super)string theory can NOT give a well-defined/unique prediction of why the electron (muon, tau) or the neutrino (any flavor) masses have the masses we measure. String ...
84
votes
24answers
10k views

How can you weigh your own head in an accurate way?

I read some methods but they're not accurate. They use the Archimedes principle and they assume uniform body density which of course is far from true. Others are silly like this one: Take a knife ...
0
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1answer
145 views

Can inertial mass affect gravity of the object? [duplicate]

Every time I watch this TV program that discusses about all the facts about the universe , and it came to a point where they said that as an object approaches the speed of light the mass of the object ...
1
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1answer
271 views

What happens when I increase the density of a stellar object so that its mass surpasses the Schwarzschild limit?

We know that every object that has mass, also has a Schwarzschild radius $r_s$: $$r_s = \frac{2Gm}{c^2}$$ With $G$ being Newton's gravitational constant, $m$ the mass of the object and $c$ the speed ...
2
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1answer
612 views

Why some particles interact with the Higgs field and others don't?

Why some particles interact with the Higgs field and others don't? Higgs doesn't explain that much: why some particles have mass and others don't? is like why some particles interact with the Higgs ...
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1answer
96 views

Force-Weight Pinewood Derby Car [closed]

Force-Weight Pinewood Derby Car. I'm trying to make a fast derby car. I was wondering if I could make a car that can drop/eject weight once it comes off of the incline. Would that increase speed or ...
2
votes
2answers
190 views

Barbells and gravity

A giant set of bar bells floating in space (like two identical sized planets connected by a long rod) would have a centre of mass midway between the two on the connecting rod. But surely it would ...
13
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3answers
1k views

Are Newton's “laws” of motion laws or definitions of force and mass?

If you consider them as laws, then there must be independent definitions of force and mass but I don't think there's such definitions. If you consider them as definitions, then why are they still ...
1
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1answer
178 views

How to know electron and muon neutrinos are different except measuring mass

Before the discovery of neutrino mass, how did people aware electron and muon neutrinos are different?
7
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2answers
594 views

An atomic bomb explodes inside of an “unbreakable” container which is on a scale. Does the “weight” of the container change?

This may or may not be an incredibly stupid thought experiment, but a short time ago I read that most of the "mass" in the proton was actually energy from the quarks and gluons, as opposed to the ...
2
votes
2answers
648 views

Can the mass of an orbiting object and the object being orbited be determined by the distance and orbit velocity alone? [duplicate]

This question is the inverse of: "Could an object orbit while moving at twice the speed, but at the same distance, if it had half the mass?" I'm curious about the nature of orbits, but am not well ...
1
vote
1answer
127 views

Are there (or could there be) electrically charged particles that move at the speed $c$? [duplicate]

A photon, a neutrino (if it has zero rest mass) move at $c$ but what about charged particles? If the answer is no, is there a fundamental reason or just because of the radiation it emits?
2
votes
1answer
120 views

Since when the term 'mass' is being used in physics?

I was wondering who used the term 'mass' in physics and in what context? The Online Etymology Dictionary says it is in use since 1704. According to the Wiki article the year is contemporary to the ...
-2
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1answer
168 views

Mass - Gravitational pull - centrifugal force

In relation to mass/gravitational/centrifugal force. Is the increased gravitational force due to the increase in mass of a planet (i.e. earth) from meteorites, etc.. directly proportional to the ...
5
votes
1answer
274 views

Relation of Higgs couplings to masses of fundamental particles

The standard model has 12 massive leptons and 2 massive bosons other than the Higgs. My understanding of the Higgs mechanism is at about the level of this article, which goes as follows. Start with ...
2
votes
4answers
357 views

Conversion of mass and energy

First of all I am not a scientist and all these doubts are coming from my curiosity. When Googling about Einstein's $E = mc^2$. I understand that mass and energy are convertible. What it exactly ...
8
votes
2answers
590 views

Why do neutrinos propagate in a mass eigenstate?

I am aware that flavor $\neq$ mass eigenstate, which is how mixing happens, but whenever someone talks about neutrino oscillations they tend to state without motivation that when neutrinos are ...
2
votes
3answers
1k views

How does energy convert to matter? [duplicate]

To my understanding, matter and energy are one and the same. Shifting from $E$ to $M$ in Einstein's famous equation requires only a large negative acceleration. If $M$ really is $E/c^2$, does that ...
0
votes
3answers
194 views

Question about negative mass [duplicate]

How is it possible to have negative mass for negative mass means something that has less mass even than nothing ? Does nothing has mass? And how is nothing a reference.
4
votes
2answers
9k views

Does a scale measure weight or mass? [closed]

What does a measuring scale measure: mass or weight? I mean, when we stand on a weighing scale the reading we get is in $\mathrm{kg}$'s. What does this mean?
4
votes
1answer
239 views

Imaginary masses

While watching this video, at around 5:00, the man mentions a certain type of particle having imaginary mass. He also says that these kind of particles can go faster then light. But how it is possible ...
3
votes
1answer
213 views

Complex masses for Dirac and Weyl spinors

I'm trying understand how to rotate Dirac fields to absorb complex phases in masses. I have a few related questions: With Weyl spinors, I understand, $$ \mathcal{L} = \text{kinetic} + ...
1
vote
0answers
68 views

Finding the force of an object? [closed]

Sorry if my initial question was seen as a "homework question" but I don't really know how to go about asking this type of question. I have a feeling I have to use Newtons law but there is no ...
3
votes
1answer
173 views

Doubts about the definition of mass

I'm having some problems understanding what are the possible definitons of mass and how they are related to each other. In Classical Mechanics, we can distinguish between inertial and gravitational ...
6
votes
2answers
275 views

Mass gap for photons

I am puzzled by the answers to the question: What is a mass gap? There, Ron Maimon's answer gives a clear-cut definition, which I suppose applies to any quantum field theory with Hamiltonian $H$, ...
-6
votes
1answer
169 views

Does the magnitude of a mass affect the velocity?

Imagine that I shrink my entire mass to fit within the volume of a light particle. If I was then 'hit' by another light particle would my greater mass affect my gain in velocity from this collision ...
5
votes
3answers
2k views

Moment of Inertia (triangular plate)

I want to generalize the formula for the MOI of a triangular plate (sides $a,b,c$) about an axis passing through mid point of one sides and perpendicular to it's plane . The mass of plate $M$ is ...
4
votes
3answers
242 views

Precision of Coulomb's law

Up to which precision has the coulomb law proven to be true? I.e. if you have two electrons in a vacuum chamber, 5 meters appart, have the third order terms been ruled out? Are there any theoretical ...
2
votes
2answers
2k views

Does inertia increase with speed?

I have heard that when the speed of the object increase, the mass of the object also increase. (Why does an object with higher speed gain more (relativistic) mass?) So inertia which is related to ...
1
vote
1answer
162 views

Defining the star as the ellipse focus rather than the barycenter, what does the other focus do? [duplicate]

There are a lot of images and animations on the internet depicting two bodies orbiting around their common barycenter. The barycenter is defined as the (let's say right) focus of the ellipse. If we ...
13
votes
3answers
6k views

Your Mass is NOT from Higgs Boson

Your Mass is NOT from Higgs Boson? http://www.youtube.com/watch?v=Ztc6QPNUqls This guy can't be correct, right? He argues that because mostly of a nucleus' mass is made out of the space between ...
0
votes
3answers
257 views

Mass in special relativity

I have just got a query about how this equation works if its right. We have Newtonian Physics saying $F=ma$, According to the 'Mass in special relativity' the mass changes according to $$m= ...
1
vote
1answer
384 views

Why does Lorentz factor not hold for relativistic mass when we apply it to photons? [duplicate]

We know that the photon itself is massless particle $m_0=0$. But we also know, that the mass of the objects does increase with their energy. And we know that under certain circumstances (gravity, ...
14
votes
3answers
800 views

Does relativistic mass have weight?

If an object was sliding on an infinitely long friction-less floor on Earth with relativistic speeds (ignoring air resistance), would it exert more vertical weight force on the floor than when it's at ...
6
votes
3answers
382 views

Is it possible to have a singularity with zero mass?

A singularity, by the definition I know, is a point in space with infinite of a property such as density. Density is Mass/Volume. Since the volume of a singularity is 0, then the density will thus ...
0
votes
1answer
176 views

Is the speed of light related to the mass of the universe?

If the mass of the universe were cut in half, would it affect the speed of light? Would it be twice as fast? Would it stay the same? Do we have instruments that are sensitive enough to measure the ...
3
votes
2answers
303 views

Do photons have mass? [duplicate]

As a student in a highschool physics class, my teacher has repeatedly told me that photons are massless. Yet, I have also heard from other sources that photons have momentum. If photons were to have ...
10
votes
1answer
384 views

How the inverse square law in electrodynamics is related to photon mass?

I have read somewhere that one of the tests of the inverse square law is to assume nonzero mass for photon and then, by finding a maximum limit for it , determine a maximum possible error in ...
0
votes
1answer
97 views

Period of oscilation [duplicate]

Two masses $m_1$ and $m_2$ are connected by a spring of spring constant $k$ and slide freely without friction along horizontal track. What is period of oscillation? No force influence.
2
votes
2answers
117 views

Can the effects of a person's mass upon the local gravitational field be detected and measured remotely?

As the title suggests, Can the effects of a person's mass upon the local gravitational field be detected and measured remotely? I am aware any mass produces and effects gravity but couldn't find ...
0
votes
2answers
2k views

What is the mass of a photon moving at the speed of light? [duplicate]

What is the mass of a photon moving at the speed of light? And if it does not have mass, how is it affected by gravity? Also why does Einstein's general relativity support that a gravitational wave ...
5
votes
1answer
313 views

How did Newton find out force has something to do with acceleration?

Its about Newton's second law of motion, $$F=ma.$$ It says the acceleration of an object is directly proportional to the net force and is inversely proportional to the object's mass. Yes I can ...
0
votes
3answers
272 views

Mass equals Moment of inertia when constant density?

I have found equation for moment of inertia $(J)$. I'm calculating $J$ for hemisphere, with rotational axis $Z$. $$ J = \iiint\limits_V r^2 \cdot \rho \cdot dV $$ But if $\rho$ is constant ...
2
votes
3answers
300 views

What truly is mass, and is there a direct way to measure it?

We know a mass of an object of one kilogram as an object that weighs W = mg = 9.8 N and we reference it to that, (when it should as a fundamental parameter describe weight not the opposite). But if we ...
1
vote
1answer
83 views

A sphere, a simple object?

In this video, the woman says that a sphere is a pretty simple object. What intrigues me is the use of a sphere for such a calculation. First of all, the sphere wouldn't be perfect as a perfect sphere ...
-1
votes
1answer
112 views

How do we know that light is massless? [duplicate]

Almost everybody knows that light is massless. But where this come from and how it can be proven (experimentally or theoretically)? I actually found this article which explains and calculates the mass ...
4
votes
1answer
292 views

Mass-energy equivalence and Newton's Second Law of motion

According to Einstein's Mass-energy equivalence, $ E = mc^2$ OR $ m = \frac E{c^2}$..... (1) and According to Newton's Second Law of motion, $ F = ma$ OR $m = \frac Fa$ ..... (2) If we compare eq. ...
-2
votes
3answers
2k views

Does a photon have mass? [duplicate]

I have seen questions assume photons have no mass. But I have not seen any questions that directly ask whether or not photons have mass. If photons have no mass, then how do they occupy space? How ...