# Tag Info

1

For case 1), heat exists in forms of oscillations of molecules. That is to say, the microparticles move back and forth in random directions but assumed never synchronized in one direction and never come back. The heat flow direction is the same as the kinetic energy gradient direction, but nothing about the displacement of the system. In the end, I would say ...

0

From your description, I think the quantity you are talking about is similar to the concept of inertia where the mass is abstracted into a matrix through its distributions in space. Mathematically, you can understand the matrix properties as following: For a positive semi-definite matrix, the Eigen values are always real and non-negative which makes sure ...

0

We'll call the acceleration of the two boxes $a$. They have the same acceleration $a$ because they're moving together. We know from Newton's second law that for any mass $m$ the force is related to the acceleration by $F = ma$. The force required to push the two boxes (labelled $F$ in the diagram) is given by: $$F = (m_1 + m_2)a$$ and that force is ...

0

$m_1g - T = ma$ $3T -m_2g = ma$ Solving these, and taking $m_1=m_2$, We get, $a=g/2$ Which is same as Daniel's answer.

0

The mass m2 is hanging from what is known as a Luff tackle, which has a 3:1 ratio. This means that, from the string's viewpoint, the system acts exactly like a mass of size $m2\over 3$; the inertia is one third of m2's, and the force generated by gravity is equal to $gm2\over 3$. Since m1 and m2 are equal, this means that the system is equivalent to a ...

0

The process of evaporation and condensation at the interfacial boundary between a liquid and gas is governed by models developed in statistical mechanics. The probablity that an atom or molecule of liquid will leave the interface into the gas or otherwise enter the interface is determined by a number of factors including temperatures of the gas and liquid, ...

2

Mercury is slightly soluble in water. At room temperature the solubility is about 56$\mu$g/litre. So while the mercury would not evaporate if you added enough water, or kept replacing the water, the bead of mercury would eventually dissolve away. In principle the mercury solution could evaporate the mercury into the air, but in practice the rate of ...

1

So the Hamiltonian is $H = \frac12 m v^2 + \frac12 m \omega^2 x^2$and therefore we can define $u = v/\omega$ to find that the circle swept out (of radius $x = a$) has $ux$-area $\pi a^2$ or $px$-area of $\pi~m~\omega~a^2.$ Presumably you mean that this area is $2\pi E/\omega,$ independent of mass at constant energy and frequency. Other combinations will lead ...

0

There are different system of units like gravitational,SI, MKS. I have seen in some text as slug as the unit of mass in gravitational system.So mass of 25 kg weight is 25/9.81 slug of mass.

1

How can photons/particles/objects/things be massless? Photons aren't massless the way people think. A photon has a non-zero "inertial mass" and a non-zero "active gravitational mass". But it doesn't have a "rest mass" because it's never at rest. You can't slow down a photon like you can slow down an electron. Or speed it up by pushing it. Rest mass does ...

1

Fire is a series of actions and changes that produces a result — a process. In fact, it is an oxidation process (called combustion or burning) that gives out heat and light energy as well as glowing gas and a small amount of plasma. So, talking about fire's mass is like talking about the mass of digestion, or boiling, or getting a driver's license — ...

2

The vertically downward gravitational force exerted by the Earth of mass $M$ on a object of mass $m$ standing on the surface of the Earth is given by: $F=G\frac{m \times M}{r^2}$ where $r$ is the radius of the Earth. Now add a dog standing close to you, also on the surface of the Earth, then the dog would exert a (negligible) more or less horizontal force ...

1

I mean, technically it would affect F, yes. But the mass of your dog is negligible compared to the mass of the planet. Just going off of Earth, we're talking 6e24 kg compared to 50 kg at most. The gravitational force from the planet is so much more than the gravitational force from the dog - which is why in real life we fall towards the Earth, not towards ...

0

Yes, there will still be a mass because mass is the amount of matter in an object so there will always be matter in an object.

0

The law of conservation of matter (or more specifically, mass) has been disproved a long time ago. There are many ways to disprove it. For eg if you bring matter in contact with antimatter, it completely annihilates, leaving no mass behind.

1

...the Relativistic Mass is defined as... is wrong. There is no relativistic mass. The mass is $m_0$ according to what its meaning is (namely, as coefficient appearing in the Lagrangian in correspondence of some terms) and does not change; rather, what changes is the way it enters the equations of motion, which in turn show an additional ...

0

So, even though they are measured in grams (which you correctly assessed as a unit of mass), it is quite all right to call these objects weights. That is because the word weight can refer to the force of mass times acceleration due to gravity or "a body of determinate mass." (dictionary.com)

0

If you pick up a weight and bring it some other place, then the weight at that other location will not be exactly the same. Wat happened to the difference between the initial weight and the final weight? Because weight it is not conserved, nothing needs to have happened. If you had instead said that you picked up a mass and brought that mass to that other ...

3

It is absolutely fine to call these objects "weights", since you are interested in their weight - i.e. the force of gravity on them. You are not using them for their inertial properties. Dictionary definition of weight: (Dictionary.com - definition 5) a body of determinate mass, as of metal, for using on a balance or scale in weighing objects, ...

1

To shamelessly steal what James says above: the scale doesn't measure your mass, which remains the same no matter where you are, or what movements you make. The scale measures your weight, which is your mass multiplied by the acceleration due to the Earth's gravity, acting between your feet and the base of the scale. You will measure your correct weight ...

1

No, the cited equation is not justified by the relativistic energy formula in the derivation the OP asks about. The corresponding text of the derivation is as follows: For the momentum of our photon, we will use Maxwell’s expression for the momentum of an electromagnetic wave having a given energy. If the energy of the photon is E and the speed of light ...

6

Let's consider two separate things: The mass (i.e. rest mass) of anything doesn't depend on its relative motion to an observer (i.e. is Lorentz invariant). For a proton, $m_p\simeq 1\,\text{GeV}/c^2$. The energy (occasionally egregiously called mass or relativistic mass in old-fashioned sources) of an object isn't Lorentz invariant. In the future, the LHC ...

1

The general Energy equation is $$E^2 = (mc^2)^2 + p^2c^2$$ where m is rest mass. Since in case of photon rest mass is 0. So we will get $$E = pc$$ $$p = E/c$$

0

Well, if you accept energy-momentum conservation, then the equation you referred to can be easily obtained from the energy-momentum relation of E^2=(p c)^2+(mc^2)^2, where E is the energy of the particle, p is its momentum, m is its rest mass, and c is the speed of light (see Energy–momentum relation). For photons, the rest mass is zero, so this equation ...

0

Looking at the literature, and please tell me if I am wrong, it seems that the yukawa couplings fail to unify. This seems to counter the intuition that all the particles in a multiplet should have the same mass, but surely it can be argued that the mass of the multiplet is zero until the higgs mechanism is activated. (Still, comments are welcome about this; ...

0

If we continue the running of quark masses with energy (due to renormalization), what are the mass values we get for the six quarks at Planck energy? Is the sequence of mass values the same at Planck energy or do some quarks "catch" up with others? Here is the definition of Planck energy: Note the 10^19GeV. The electroweak symmetry breaking is at ...

0

I think that your idea of mass is a little wrong. The quark mass is given in a renormalization scheme, if you change it you would have different masses for quarks. But for example the pair production is a physical process, in fact, if you do a pair production with all the radiative corrections you will find the same energy with whatever renormalization you ...

1

Firstly, it's hard to imagine the first particle alone getting all the kinetic energy: the most obvious scenario is with the atom at rest, so the total momentum of all the fragments in the center of mass frame is nought. However, supposing it were possible for the first particle to get all the kinetic energy, then the total energy of the first particle is ...

1

Because of conservation of mass, the fact that things on Earth are composed of trees, buildings, etc, doesn't matter - the only time the mass of the Earth will change is if things physically leave the Earth. According to this article the major change in the mass of Earth is due to about 10$^5$ kg of Hydrogen and Helium escaping from the atmosphere every ...

1

That depends on how you found that weight. If it is calculated from the gravitational pull, then all things on earth are included since they add to the mass. If it is calculated through geological measurements then maybe they are not included. In any case, try to multiply 80 kg or so for an average human with 6 billion. Try to add an estimate for ...

1

As all living cells take their matter from the earth, the overall mass stays constant. The earth is (mostly) a closed system with only very few exceptions: Gases, that are light enough to escape the earth atmosphere (I think this can happen to helium) The stuff humans send into space using rockets A (tiny) bit of mass is added to earth by the sun's energy ...

0

The atoms that makes up life on Earth comes from the earth itself. It included in that estimate. Do you want to make an estimate of the mass of all biomass?

1

The neutrino is a weakly interacting particle, thus it has some quantum numbers (weak isospin, hypercharge) which is summed to zero in the black hole. Thus, even if we don't take in sight the numerous related problems (see Annas answer above), the answer is no.

1

A priori, they could have been different things. The Equivalence Principle - the hypothesis that they are actually the same - is a core input the General Relativity. To the extent that General Relativity is empirically validated, we have evidence that these really are the same. There's no complete theory of quantum gravity, so I think we'd have to say ...

4

Lets take this a step at a time. A black hole is an object posited by the classical theory of General relativity. It is a legitimate solution for the case of a great accretion of mass which has a singularity at the origin, and it has a definition of a radius called an event horizon which once any mass goes through it cannot come out because of the great ...

2

My own impression is that the ball got stuck in someone' roof, but I am partial because some of my numerology did coincide with the relationship $(m_u,m_d,m_s) \propto (0, 2 - \sqrt 3, 2+\sqrt 3)$ proposed by Harari Haut Weyers (1978) (presented by Harari here) when trying to find some first-principled calculation of Cabibbo angle. My understanding is that ...

3

In the standard model of particle physics which fits the data up to now elementary particles entering the lagrangian are point particles with mass. The electron, for example is one of the elementary particles, and it does have a mass and the fit gives it 0 volume. There are experiments which try to set limits to how small the volume of the electron is. ...

1

Your Transformation is wrong and it is easy to see that. Your transformed derivative of $\partial_{r_2}$ does not depend on the $r = r_1-r_2$ part of the transformation at all. In other words with your logic I could equally write $\partial_{r_2} = \frac{\partial r}{\partial r_2} \partial_{r} = - \partial_{r}$. The correct transformation is \partial_{r_2} = ...

-4

Is it possible for an object to have mass but zero volume? No. Can there exist a particle/object in the universe having mass but no volume? No. Is it possible that mass can exist without volume and density? No. We think we know that matter is anything having mass and that it occupies space, but is it possible that this statement is ...

0

Based on the latest breakthroughs in particle physics, the answer is a plain NO - it's not possible for a massive particle to have no volume. In fact, it is NOT possible for any particle, whether massive or massless, to have zero volume. ALL particles have a certain volume, no matter how small beyond observation. On the contrary, mass is an intrinsic ...

3

Your question states that We think we know that matter is anything having mass and that it occupies space but in fact, we know better than that. We have good reason to believe that fundamental particles are point-like. In other words, they have no internal structure, size, or volume. And they indeed have mass. We have a theoretical understanding (in ...

1

I'll address your question a little different, because talking about volumn and particles is problematic in many ways. Let's phrase your question "can there be two particles with mass be at the same place". The answer is yes. There are two types of particles:fermions and bosons. While fermions (electrons, protons) repel each other (not only because of the ...

6

This admittedly, isn't much of an answer, as I'm merely repeating information from the Particle Data Group page about the up-quark, which I consider up-to-date. Their current combination is that $m_u = 2.3^{+0.7}_{-0.5}\,\text{MeV}$, but they warn that The $u$-, $d$-, and $s$-quark masses are estimates of so-called "current-quark masses," in a ...

0

Why not design a self-contained power source into the gloves that sends 3 to 5-second bursts of taser electricity into the muscles in the superhero's arms every few minutes, effectively locking them up so he can't move them? You could design the gloves with a flexible capacitor molded into the palm. The power supply could be molded into the back of the ...

-1

$p=mv$ is true for relativistic mechanics as well. But one should be careful about the definition of $m$. There are two type of masses, rest mass, usually denoted as $m_0$ and the relativistic mass $m=m_0/\sqrt{1-v^2/c^2}$. When physicists say "a particle is massless", this is a jargon which actually means the rest mass $m_0=0$. Photon has no $m_0$, but it ...

3

If the object is spinning close to the speed of light then it has significantly more energy than if it were at rest. This does contribute to an increase in gravitational pull and is significant in astrophysical phenomena like neutron stars! http://arxiv.org/pdf/1003.5015.pdf The Earth is also more massive because its spinning but we have no hope of ...

0

A proof that the weight is what you said. Look at the free body diagram and assume the conditions outlined by BowlOfRed apply: For each plank the sum of vertical forces is $W=2F$, so $F=W/2$. Since as two of these forces act on the scales these will read the weight of a single plank. The torque balance on each plank is $FL=WL/2$ ($L$ is the length ...

0

In the limit where All supports are exactly the same height All supports are perfectly level The planks are perfectly flat The material has the same amount of overlap on the inside and outside supports then you would be measuring the weight of 1 plank and the center support under the center scale. If we assume that the planks are symmetrically ...

0

Some of the modified workings out and an answer: Volume of cube = $l^3$, and of the pyramid = $\frac{l^3}{3√2}$, using the height of the pyramid as $\frac{l}{√2}$, from Pythagoras. If $O$ is at the base of the pyramid we can say that for the pyramid the height above $O$ is $\frac{l}{4√2}$, as the centre of gravity (centre of mass) is $\frac{h}{4}$ above ...

0

The force of friction is greater in heavier objects. Moreover the object is attached to the ground. The force applied by us is not strong enough to pull it out. That's why the wall didn't move

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