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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4answers
5k views

If something weighs 25 kg, how do I find the mass of the object?

An object is falling and it weighs 25 kg (on a scale, presumably). What is its mass? I know that weight is measured in Newtons and mass in kilograms, but what if a problem states that something ...
0
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0answers
111 views

Can a black hole move at speed of light?

Black hole comes in all sizes ranging from microscopic black hole on a quantum scale to supermassive black hole that resides in the center of probably every galaxy. Photon have no rest mass hence they ...
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1answer
46 views

Fire: Understanding the states of matter and its mass

If the fire is a state of matter (plasma) and every matter has mass. My question is: how we can calculate the mass of a fire?
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1answer
100 views

How can photons/particles/objects/things be massless? [closed]

How could we say a photon be massless? A thing which has no mass is seem to be just like it does not exist or we say it is nothing. It should be very less but we can't say "massless". Everything which ...
2
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2answers
319 views

Law of conservation of matter

If scientist have made small particles of matter then why do we still haw the law of conservation of matter? Is it because the few particles don't make a noticeable difference in our life?
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0answers
98 views

How do gravitons transmit gravity to occulted bodies?

If matter feels gravitation by way of absorbing gravitons, how is it that gravity passes through matter unfettered? For instance during a solar eclipse; shouldn't the moon block at least some of the ...
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2answers
75 views

Do other people's mass count when measuring the attraction of the earth on me? [duplicate]

Suppose that I'm alone on a planet of $M$. From what I learned from school, the gravitation force acting on me is given by $$F=G\frac{mM}{r^2},$$ where $m$ is my mass, $r$ is the distance between me ...
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1answer
94 views

What's the deal with Relativistic Mass? [duplicate]

So I have taken a first course in Special Relativity and the Relativistic Mass is defined as: $$m = \frac{m_o}{\sqrt{1 - v^2/c^2}}.$$ Now, when this was introduced in the course, it was introduced as ...
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3answers
188 views

Should these be called “weights” or “masses”? [closed]

Yeah, those circular metal disks. Weights or masses? I call them weights because when I attach them to a spring I'm interested in their weight, but it feels odd saying a "Pick up the 100g weight". ...
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3answers
18k views

Why do we use kilograms instead of newtons to measure weight in everyday life?

What was the reason to use kilograms to measure weight (e.g. body weight, market vegetables etc.) instead of using newtons?
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6answers
6k views

What does it mean to say that mass “approaches infinity”?

What does it mean to say that mass "approaches infinity"? I have read that mass of a body increases with the speed and when the body reaches the speed of light, the mass becomes infinity. What ...
4
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1answer
187 views

Why is the apparent weight smaller when you crouch down on a scale?

I am having a problem understanding the concept of the apparent weight change when you crouch down, stand up, and jump on the scale. What is happening that makes the scale change?
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1answer
274 views

The (relativistic) mass of a proton in the LHC

What would be the (relativistic) mass of a proton, in grams, as it is traveling at the maximum possible speed in the LHC?
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3answers
94 views

Justification of $P_{\text{photon}}=E/c$ in derivation of $E=mc^2$

I recently was reading up on the derivation of $E=mc^2$. Now, I came across this derivation at this link. I noticed that several lines into the derivation they throw in the equation ...
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1answer
119 views

Mass of a particle ( relativity)

A hypothetical atom has a rest mass of $15.000000136\,\mathrm{u}$. Overtime it undergoes a spontaneous breakdown into two masses of $7.000000229\,\mathrm{u}$ and $6.902727019\,\mathrm{u}$ ...
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4answers
108 views

Does not the mass of those living on the Earth add on to the mass of the Earth or is it too negligible to be cared for?

Source: Earth weighs about 13,170,000,000,000,000,000,000,000 pounds (or 5,974,000,000,000,000,000,000,000 kilograms). Since Earth is too big to be placed on a scale, scientists use mathematics ...
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2answers
93 views

Is a blackhole just a neutrino with much more mass?

If there was a blackhole that had a mass similar to that of a neutrino ($0.320 ± 0.081\,\mathrm{eV/c^2}$), would we still be able to differentiate the blackhole from the neutrino? Is there any ...
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5answers
1k views

Is it possible for an object to have mass but zero volume?

Can there exist a particle/object in the universe having mass but no volume? Is it possible that mass can exist without volume and density? We think we know that matter is anything having mass and ...
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2answers
547 views

Point masses and infinite densities

Point masses are masses who don't have volume. It is said that they are infinitly dense, but I though division by zero is undefined hence you can't define the density for a point mass because ...
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1answer
67 views

Two-body systems quantum physics (Transformation) [closed]

Given the Schrödinger equation $i\hbar \frac{\partial}{\partial t}\Psi(\vec r_1,\vec r_2,t) =\left [ -\frac{\hbar^2}{2m_1}\nabla_{r_1}^2-\frac{\hbar^2}{2m_2}\nabla_{r_2}^2 +V(\vec r_1,\vec r_2)\right ...
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1answer
1k views

Reduced mass in quantum physics (Hydrogen Atom)

I've gone through an intermediate classical mechanics course, and in solving the two-body problem, we reduce it to a one-body between a larger stationary mass, and a smaller reduced mass. Most ...
6
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3answers
3k views

Have I discovered how to calculate the proton's mass using only integers?

Could it be possible that the mass of the proton can be calculated by a series of integer sequences? Or is this just a curiosity? $$\sum_{m=1}^{\infty } \frac{1}{10^{26}(m^2+1)_{2m}}=$$ ...
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1answer
63 views

Applying downward force on someone without adding to their weight

I am creating a scenario for a superhero comic, and need help with an idea. I'd like the solution to be based in scientific theory, or at least scientific fantasy, as opposed to resorting to simply ...
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1answer
106 views

Do photons have no mass? [duplicate]

My Quantum Mechanics' teacher said today on the class that photons don't have mass. I was puzzled because I knew that photons have momentum. If a particle hasn't mass then its momentum sould be $0$ ...
3
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1answer
143 views

Does a rotating object have more inertia, mass and gravitational pull?

When an object is rotating on an axis, it has stored rotational energy in it. Since energy and mass are related, does this stored rotation increase the mass of the object? And if so, will it be harder ...
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2answers
75 views

Planks, supports, and a scale [closed]

I've got two equal dimension planks with the same homogenous mass. They're placed next to each other like this (bird's eye view): [ ][ ] They're sitting ...
2
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0answers
79 views

Significance of imaginary mass

Can real mass be thought of as producing a deformation in spacetime leading to a stable equilibrium (valley curve in gravitational potential energy) of the massive body, and imaginary mass as similar, ...
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1answer
390 views

Centre of gravity vs centre of mass for a pyramid mounted on a cube, all sides of length $l$ [duplicate]

A uniform solid body is constructed using a square-based pyramid mounted on a cube. If each edge of the solid has length $l$ show that the centre of gravity of the body lies within the cube is, $\frac ...
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0answers
21 views

Flamant's use of mass and weight

I apologize for the stupid question, but I've consulted teachers and found their answers unsatisfactory. Professor E.Brune, in the XIX century, delivered a course on l'École des beaux-arts on ...
6
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3answers
2k views

Why doesn't a wall move when you push it if there's space behind it?

In the first screen you can see that if a person were to push a wall within a typical household the wall would not move while keeping themselves tractioned to the floor. If you push hard and do not ...
0
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1answer
52 views

Mass to Light Ratios

I know that the mass to light ratio for galaxies is between 2 and 10. I also know that the ratio changes primarily based on what kind of galaxy you have (elliptical, spiral, etc). Is there a table ...
0
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1answer
96 views

Is the relativistic mass of a photon non-zero?

A photon has rest $m=0$, but it is never at rest, so it has no rest mass, then the relativistic mass is according to me non-zero because: $E = \text{work}=m \times \text{acceleration} \times ...
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2answers
117 views

Will the universe reach zero mass?

I was reading Phil Plait's 'Death from the skies' where it describes the fate of the universe. It describes the period from 10^90 years to infinity as the "dark age" when all the of the black holes ...
93
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16answers
176k views

How does mass leave the body when you lose weight?

When your body burns calories and you lose weight, obviously mass is leaving your body. In what form does it leave? In other words, what is the physical process by which the body loses weight when ...
6
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1answer
1k views

Why are there 3 quarks in a proton? [closed]

A few quark related questions (I don't know much about them other than that there are 2 flavors concerning protons and neutrons). Why are there 3 quarks in a proton or neutron? Why not 2 or 4? Is ...
0
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1answer
175 views

What is the baryonic mass distribution of the Milky Way

There are many, many studies of the Dark Matter halo around the Milky Way but I'm having trouble finding good raw data about visible matter. I'm investigating a MOND like model and would like some ...
4
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1answer
668 views

Does string theory pose a photon mass problem?

A few weeks ago, I started reading books on string theory. One thing that really seemed confusing or contradictory was that string theory explains that the energy of a superstring gives mass to the ...
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1answer
56 views

One stupid question about Dirac mass term and Grassmann numbers

Let's have Dirac mass term in lagrangian: $$ L_{M} = \bar{\Psi}\Psi $$ Lagrangian must be real-valued, i.e., its Hermitian conjugation doesn't change it. But due to Grassmann nature of spinor fields, ...
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1answer
229 views

Difference between mass and weight [duplicate]

I already know that when I standing on weighing machine it's measuring my mass not my weight, but when I take the same machine to moon it's will read different value. According to my information that ...
4
votes
1answer
354 views

Why should the mass of leptons to be near of proton and QCD/chiral scales?

The mystery of the mass of the top being in the electroweak scale can be justified by the Higgs mechanism itself; in some sense the top mass is the only "natural" mass, the other masses of fermions ...
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1answer
82 views

is there an operator which measures the mass of particles?

When I studied a spin, the textbook said spin is an intrinsic quantity like mass. However, while we can calculate just expectation values $ \langle \textrm{S}^2\rangle $ or $ \langle S_z\rangle $, the ...
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1answer
74 views

Could the Big Bang have simply been two black holes hitting each other at 99% of the speed of light? [closed]

Given two equally massive black holes moving at 99% of light speed, it seems there would clearly be enough energy for most (99%?) of the mass of both to be ejected and / or radiated well beyond the ...
0
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1answer
23 views

Would a fast moving (approaching $c$) stream of particles be affected by the gravitational pull of a gas giant?

I was inspired by this SE question. Would the gravitational field of a gas giant (such as Yavin IV) have an effect on the super laser (i.e. slow it down, change the direction), or is the mass so ...
0
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1answer
132 views

Why is centre of mass taken as integral of x.dm and not m.dx?

Forgive me if I'm being naive, but, I don't understand why the X-coordinate of the Centre of mass is taken as an integral of x.dm and not m.dx. I understand the summation part, but how do we convert ...
2
votes
1answer
113 views

Interpretation of negative mass in condensed matter physics

I am reading the book "Topological insulator: Dirac equation in condensed matters" by Shun-Qing Sheng. I do not know much about this topic and this is the first time I am confronted with it, so this ...
2
votes
2answers
160 views

Lagrangian point or dark matter?

We know that spiral galaxies spin in a way such that we have to assume that dark matter is responsible for the extra mass required to do so. My question is, can Lagrangian points (L1 and L2) be used ...
0
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1answer
112 views

$U(1)$ local gauge invariance in QED [duplicate]

While constructing Lagrangian of QED, we don't add the mass term for photon $\dfrac{1}{2} m^{2}A_{\mu}A^{\mu}$ because gauge invariance does not allow. I want to ask, whether "$\bf{Theoretically}$", ...
3
votes
2answers
258 views

Can you express mass in other dimensional units?

I'm just started a Physics I course, and while I've paid attention, I'm stuck on one of the first problems: Express mass ($M$) in terms of acceleration($a$), density($D$), area($A$), and time($t$). ...
7
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3answers
3k views

Does lightning have mass?

My chemistry teacher/book states that lightning is just light, and therefore has no mass and takes up no space (we're not very far through the book yet, it's defining matter). However, I take issue ...
3
votes
4answers
271 views

Is there difference in force when the height increases?

Consider a man with mass 50kg. When he jumps from a 2 meter height, the total force is $F=ma$ ie (mass * gravity), but nothing happens to him. When he jumps from a 50 meter height, the total force ...