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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Theoretical Possibility of “Opposite” Gravitational Mass? [duplicate]

This is an unusual idea that I have been entertaining for some time, and I can't find anything about it online. However, it is so simple that someone must have conceived it before. First, I will ...
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3answers
51 views

2 airplanes same size and shap different mass

2 identical balls of different mass dropped from same height reach the ground at the same time due to the acceleration of gravity being constant. If I understand correctly the ball with more mass ...
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3answers
115 views

How does a mass create the gravitational field of GR? [closed]

As far as I understand, and please correct me if I am wrong, but the basic idea of general relativity is that spacetime is curved by matter. What we call gravity is then not a force as per Newton but ...
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1answer
141 views

Is it true that the standard model does not predict the mass of the electron?

I read that the standard model has parameters that have to be put in such as the mass of the electron, because nobody has been able to calculate the mass of the electron. Is this true?
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1answer
35 views

How to calculate relativistic mass versus time?

I know that relativistic mass is calculated as: But when mass m0 gets bigger, also mass of the accelerating body mass m gets bigger so m0 gets bigger and so on. So if body accelerates with ...
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1answer
72 views

Constructing a Hamiltonian from a mass matrix?

I was solving some questions regarding the Hamiltonian, which required a lot of algebra, but as I finished and looked professor answer I saw that he constructed a matrix from the kinetic energy and ...
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63 views

How much Oxygen is in ζ-phase metallic Oxygen?

I am playing with a sci-fi idea of Oxygen storage for breathing. I wonder how do some compressed forms of Oxygen compare to human-breath-Oxygen (room temperature, room pressure) in terms of density. ...
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2answers
54 views

Acceleration due to gravitational force [duplicate]

I need some help with below. So according to Newton's 2nd law, $a=F/m$, for a given mass, the acceleration depends on mass. But acceleration due to gravity is independent of mass. There seems some ...
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59 views

Weighing a baloon

I know of methods of measuring the mass of a gas using chemistry, but this is unrelated. I was wondering if it is possible to deduce the mass of a helium balloon by measuring its mass it on a scale ...
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1answer
58 views

Does energy flowing from one place to another in an object cause displacement of that object?

Let's consider two situations: a) A solid metal box (not hollow) where some heat is put on its left side. After some time, the heat will have moved to the right and also have spread out throughout ...
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2answers
171 views

Can mercury evaporate if it's covered by water?

I was recently watching a video about elemental mercury and how it's cleaned up in water (fish tanks), and it was mentioned how mercury can be toxic in vapor form. My question is, if I were to drop a ...
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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 ...
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1answer
116 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 "$\bf{Theoretically}$", ...
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2answers
119 views

Why is a silicon ball with an exact number of atoms a bad measure of mass?

I have some friends that are talking about why a silicon ball with an exact number of atoms is a good/bad measurement of mass (1kg) and things are getting pretty exotic. Is there a layman's ...
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1answer
82 views

Current constraints on lightest neutrino mass?

This paper from 2005 claims that the mass of the lightest neutrino is unconstrained. (see p9) Oscillations are only able to constrain the differences in squares as far as I know, but perhaps ...
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2answers
60 views

How the mass is conserved during continuous expansion?

If universe is continuously expanding doesn't it contradict the fact that mass is conserved? Because if mass is conserved so how is universe expanding?
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127 views

How to calculate centre of mass

How do I find the centre of mass with given coordinates? For example if we have four objects with mass $m$ at coordinates of a square $(0,0,0),(0,0,a),(0,a,0),(0,a,a)$ or another example with eight ...
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1answer
193 views

Does mass distribution/center of mass affect free fall?

An everyday is example would be cars. If you were to drop a car, not taking air resistance into account, would a front-heavy car tumble forward as it fell? And a car with a perfect 50/50 front/rear ...
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1answer
354 views

Minimum size of black hole

What is the minimum size a black hole could be? I have been told that they were worried that the LHC would create a black hole, yet they say the Sun cannot be a black hole. I understand that the ...
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1answer
36 views

Is density of a material related to penetration?

Theoretical question. If you have a standard projectile with mass 1 and velocity 1 and fired it at different materials would the penetration be related to the density of the material? I'm not trying ...
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2answers
106 views

Are black holes an infinite source of energy? [duplicate]

Black holes are considered particularities because in a determined point in time they are pointless, as consequence there are some mass in a null space so the density become infinite. Finally if ...
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1answer
96 views

Metric in Lagrangian and the minimum total potential energy principle

I was wondering why physical systems "like" to go to the minimum of potential energy and I found this question, that tries to justify the minumum total potential energy principle. I was also reading ...
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1answer
105 views

What are the effects of increased mass on persons traveling at near light speed?

It's been a long time since I studied physics (and then only very superficially), so please bear with my gross naivete. This question's been running around in my head for about two weeks now, and I ...
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1answer
42 views

Is anything without mass an EM wave?

For the longest time I thought the distinction between matter wave and other types of wave is the non-relativist mass of the "thing" under discussion. Photons are EM wave, electrons are matter waves. ...
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1answer
54 views

Higgs field and the null geodesic

How does coupling to the Higgs field take a particle with a spacetime interval of zero and give it a non-zero value, i.e, how does it move it off the null geodesic? [of course, the Higgs field is ...
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2answers
1k views

Why is the force of Friction less than the force applied on the block in this situation?

This is a seemingly basic mechanics problem but I'm having a dilemma in understanding what happens. You start with two blocks, one on top of the other (the bottom block has a larger mass than the top ...
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1answer
72 views

Does mass equal angular momentum?

At the wikipedia pages for angular momentum ($L$) and moment of inertia ($I$) we find the equations: $$L=I \omega$$ $$I=m r^2$$ where $m$ is mass and $r$ is the distance between said mass and ...
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1answer
122 views

What is the mass of the universe?

Working with a flat and infinite model of the universe (which seems to be the most popular serious model these days), the density of the universe is 3e-28 kg/m^3 [1]. When added to the cosmological ...
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1answer
284 views

Density as a function of Temperature?

I know that volume = mass/density....and density is the function of temperature. Is there any standard equation that describes density as a function of temperature? The system I am interested in is ...
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2answers
974 views

How can I calculate the initial velocities of a set of objects with a consistent force?

I'm trying to figure out which object would have the largest time of flight when launched from a slingshot. To do this, I need the initial velocity. How can I calculate this if I know the mass and ...
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4answers
165 views

Mass in terms of special relativity

According to special relativity mass doesnt add up like we think it does. That is, a system of 2 protons might not necessarily have a system mass of 2*(mass of one proton). If the protons are ...
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2answers
180 views

Why can't I calculate center of mass via torque? Results off by a few percent

Why do I keep getting a slightly different result from the following two ways of determining the center of mass of a rigid, geometrically simple object? The object is a rectangular 5(x) by 7(y) ...
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2answers
856 views

What are the forces used in this weightlifting example? [closed]

You have a person doing a bench press. Their hands are equidistant apart and they are centered on the bar - each hand about 1.5 feet from center of the bar. The bar weighs 45 pounds. In example 1 ...
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1answer
92 views

Mass is a stuff or not? [closed]

Einstein said, there can be no clear definition can be give for moving body mass – instead of giving its name as “rest mass”, it is better to mention, “momentum and energy”. Matter is a stuff, ...
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1answer
140 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 ...
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3answers
356 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= ...
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2answers
304 views

Photons in a gravitational field

I have been really staring for a while in a MP-Beiser book and I totally disagree with a statement he does there. On a page 85 he states that photons act as they have a mass $m$. He derives this by ...
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1answer
642 views

Mass points of a Mass-spring model

Let's say I have a mass spring model like the one in the picture below: So, there are 3 parts of the spring joined together in an equilateral triangular manner. Each of the joints has a mass of ...
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1answer
489 views

Question about finding $k$ in Hooke's Law

My textbook (Advanced Engineering Mathematics by Dennis Zill) offers the following explanation of Hooke's Law: By Hooke's Law, the spring itself exerts a restoring force $F$ opposite to the ...
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4answers
550 views

Mass-Energy relation

Einstein mass- energy relation states $E=mc^2$. It means if energy of a paricle increases then mass also increases or vice-versa. My question is that what is the actual meaning of the statement ...
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1answer
296 views

Why the kilogram is not defined? [duplicate]

Possible Duplicate: Why do we still not have an exact definition for a kilogram? I was thinking about SI units. I found the following definition for the base units: Meter: distance ...
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1answer
94 views

Is mass of the parent star is equal to the mass of the born blackhole

I want to know whether mass of the black hole which has born from a star is similar to its parent star or not. whether the born black hole will have high or low mass comparing to its parent star. ...
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2answers
583 views

How far does physics influence russian roulette?

Prompted by this discussion on the math exchange My thought was that the added mass of a bullet in an otherwise empty revolver would bias the chamber spin such that the bullet would remain in one of ...
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2answers
4k views

Projectile motion without air resistance [closed]

Does the mass of projectile affect its trajectory when it is projected in no air resistance environment and why?
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2answers
424 views

How did these guys get the masses from Heim Theory?

How did these guys get the masses from Heim Theory? I won't even bother to ask about validity as I read the other post on this. So I know how we all feel about that. I hadn't even heard of it till ...
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2answers
44 views

Force on a Massless String

Suppose we are just pulling a block with the help of a string which is massless. Now since the mass of the string is 0 the force exerted by us is transmitted without being diminished. So the equation ...
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1answer
66 views

Force, Mass, Motion? $E = mc^2$

Does any object needs force to move? If 'yes', does the matter needs mass to form a force? These questions arises from me because $E = mc^2$ and $F = ma$ does not relate and one does not agrees with ...
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1answer
38 views

Properties of a body with spherical symmetry

I'm studing Gauss law for gravitational field flux for a mass that has spherical symmetry. Maybe it is an obvious question but what are exactly the propreties of a spherical simmetric body? A ...
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1answer
51 views

Why are we mentioning weight of the product in kg? Why not Newton? [closed]

I am confused using this units. Why this changes happened?
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1answer
122 views

How to measure the mass of the lower part of a human body?

An Olympic weightlifter asked me this question and it has been bugging me for a couple of days now. Suppose "lower part" is defined as anything below and including the hip. This means that the ...