Mass Definition and 1000 Threads

So the gravitational field has energy and momentum, and so you can never have a spacetime with an energy stress tensor set to 0. Is this like a constant then? that you can calculate for a portion of spacetime with no "stress energy tensor"?

Why wouldn't a brown dwarf grow in radius if it started to gain mass?

I did look it up , but couldn't find anything that explains this in a simple manner.

Hey, first of all I apologize if this isn't the right thread because I was confused of where to put this. Recently I've learned about Quantum Field Theory and the Higgs Field. I kind of understand why the Higgs Field gives particles mass. From what I have learned it's because the field is...

Homework Statement A mechanical servo-mechanism comprising of a movable piston-cylinder within a vertical cylinder operates based on a venturi contraction in a horizontal 350mm diameter pipe that delivers a fluid of relative density 0.95. The upper end of the 100mm diameter vertical cylinder is...

Hey, I'm a student who has to complete a written assignment for physics. I chose to launch water rockets and investigate the effect of volume on the range. I am trying to also come up with a mathematical model however I am struggling to understand an equation I found the following equation to...

1) space is expanding at an increasing rate, therefore things are getting farther from each other and therefore increasing in velocity. 2) the faster an object moves relative to another, the more mass it has 3) supermassive objects can turn into neutron stars, black holes, etc. Therefore, will...

Homework Statement Find the mass of photon in motion. Homework Equations E=hf p=hf/c The Attempt at a Solution I just started studying modern physics and am aware of the above two equations. However equating E to 1/2mv^2 gives a different (wrong) answer while equating p to mv gives the...

A gas stream containing 3% A is passed through a packed column to remove 99% of A by absorption in the water . The absorber operates at 25 degree Celsius and 1atm and the gas and liquid rates are to be ##20\frac{mol}{hr ft^2}## and ##100\frac{mol}{hr ft^2}##. Find the ##(NTU)_{OG}## ...

Weinberg considers (p.68 QFT Vol. 1) particles with mass M > 0. The Little Group is SO(3). He wants to calculate the rotation W(Λ,p) ≡ L-1(Λp) Λ L(p). He says that for this we need to choose a standard boost L(p) which carries the four momentum from kμ = (0,0,0,M) to pμ. He then shows the...

I read an internet meme: I was going to respond that photons are "massless" particles, but then I realized that photons have energy, and thus must have mass. What's the proper explanation here?

Hi, stuck on this question, hoping someone could help 1. Homework Statement Two identical photons of wavelength 4.22x16^-7m are created when a certain amount of matter M, is converted into energy, calculate the Mass (M) The Attempt at a Solution E= hf which is hc/wavelength E= 4.71x10^-19J...

I'm confused between partial pressure, total pressure, boiling point , vapour pressure , saturation pressure and saturation temperature.These things haunt me in my subject mass transfer. I get really confused when this words come in a liquid - vapour system, I cannot identify what these pressure...

At a post office, there are three parcels of different masses. The mass of the first parcel is y grams. The mass of the second parcel is 500 grams greater than that of the first parcel. The third parcel is 210 grams lighter than the first parcel. a) Find the total mass, in grams, of the three...

Homework Statement This is a question from a chemistry book Two oxides of a metal contain 27.6% and 30% of oxygen respectively. If the formula of the first oxide is MO, find that of the second? 3. The Attempt at a Solution In the first MO, if the total amount is 100g, then O is 27.6g...

Can we apply continuity equation between the given two cases? The only difference in the second case is that the pipe of diameter d2 is replaced by a pipe of diameter d3. Will the mass flow rate be same for both the cases.

Homework Statement Two forces F1 →= 2i ^ + 3j^N acting on a mass m1 =1.5 kg, andF2→= i^+ j^N acting on a mass m2= 1.0 kg.The magnitude of the acceleration of the center of mass of the system is?

A question of invariable mass. In a inertial system, the invariable mass of a system never change with time. This system may not be an isolated system. Whether in any inertial system, the invariant mass of the system remains unchanged.Or, in a certain inertial system, what is the necessary and...

Homework Statement A cone of height h and base radius R is free to rotate around a fixed vertical axis. It has a thin groove cut in its surface. The cone is set rotating freely with angular speed ω0, and a small block of massm is released in the top of the frictionless groove and allowed to...

Homework Statement A solid body consisting in two concentric disks of masses m1, m2 and radius r1<r2 is linked through a ideal rope to a mass m which falls down with a certain acceleration. The solid body moves of pure rolling. Find the acceleration a of the mass. Homework Equations P-T=m*a...

Homework Statement Two oxides of a metal contain 27.6% and 30% of oxygen respectively. If the formula of the first oxide is MO, find that of the second? Now my problem is how to find the atoms of O from the masses of 27.6% and 30.0 %? Homework EquationsThe Attempt at a Solution I can see that...

Homework Statement A satellite of mass m is in a circular orbit of radius R about a star of mass M. The star ejects 1% of its mass by means of a spherically symmetric wind which removes the mass to a large distance. What are the new nearest and furthest distances of the satellite’s orbit around...

Homework Statement 12 amu and 1.9924 X 10^-23g express the mass of an atom of C? Homework EquationsThe Attempt at a Solution Do 12 amu and 1.9924 X 10^-23g express the mass of an atom of C? As I know, 6.023 X 10^23 atoms of C weighs 12 g, 1 atom of C weighs 1 X 12 / 6.023 X 10^23 = 12 amu...

What does it mean by 1 amu? the mass of a proton or a neutron or an electron? If the mass of O is 16 amu, then what makes 16 amu in O atom? 16 protons or 16 neutrons or 16 electrons?

There's important experiments showing the equivalence of inertial mass and gravitational mass ( the Eotvos experiments), but I couldn't really find many that show the equivalence of mass (or the stress-energy tensor) in other contexts. These are some of the variants of mass I'm interested in...

How could electrically charged particles be massless before the symmetry breaking? Wouldn't the energy stored in the electric field contribute to particles mass?

When a high mass star starts to fuse heavier elements, the core heats up the outer layers enough to for them to begin fusion of their own. My question is: because the star hasn't gained any mass, but it has increased in temperature a lot, why doesn't the star expand and cool like a red giant...

Is 'AMU' the unit for both 'atomic mass' and 'molecular mass'?

Does molar mass include an atomic weight for single atom and molecular weight for molecules?

Homework Statement A solid rod of length L and mass M has a pivot through its center and is originally horizontal. Another mass 2M is then attached firmly to one end of the rod, and released. What is the maximum speed of the mass 2M attained thereafter? (Cornell 2009) Homework Equations Not...

Hello! Please tell me what Effective electron mass of tungsten and Effective hole mass of tungsten?

Question: Calculate the centre of mass of a uniform, square-based pyramid of height H and base length B (taking the centre of the base as the origin). Hence, or otherwise, derive an expression for the centre of mass of such a pyramid with a pyramid-shaped hollow cavity (of height h and base...

So, this is a bit of an odd question, but something I was curious about. I recently learned in layman's terms that the universe is considered flat because of how we measure triangles in 3D space, in particular the CMB. I've also learned that the cosmological constant that was derived from GR...

Proton is made of 2 up, 1 down quarks Neutron is made of 2 down, 1 up quarks The up and down quark have different masses, which account for some of the mass difference. I've also read that hadron masses depend upon the interactions/dynamics inside the particle, not just the quarks contained...

I'm trying to understand calculation made Robert Zubrin in his presentation on Dipole Drive source: In here he made the following statement "A Coulomb of protons has a mass of 0.011 milligrams. If the jet power is 400 W, and the potential difference is 64 V, so the proton current will be...

Homework Statement Two straight rods 60 cm long and 2.0 mm apart in a current balance carry currents of 18 A each in opposite directions. What mass must be placed on the upper rod to balance the magnetic force of repulsion? ## \mu_0 = 4 \pi * 10^-7 ~\frac {T * M} {A}## ## g = 9.81 ~m/s ##...

I am looking to prove or disprove the following statement: Two objects, of the same homogeneous material, the same mass, the same volume, the same center of mass and the same moment of inertia will be dimensionally the same. If there is a way to generate a mathematical proof, that would be...

The setup: I have a mass (m1)connected to a much, much larger mass (m2) via a preloaded spring. They start out in contact because the preloaded spring holds them together. Now suppose the large mass is subject to vibrations, possibly at the resonance of the structure. Will the two masses...

How much energy is necessary to move one kilogram of mass horizontally for one meter on a perfectly frictionless surface inside a vacuum chamber? Assuming the initial velocity of the mass is zero, the mass is at rest.

I have these two cases of a mass hanging from beams. The question is in which of the two cases will the mass travel the most distance in the vertical direction assuming we are in the elastic region. All i can think of is to calculate the tension for each of the two cases, Whichever case has...

Just read the FAQ post "Do photons have mass?" and I'm still confused. The post says that all of the photon's energy is in the pc term of the energy-momentum equation. (1) But isn't p equal to mv, implying there is mass? (2) The post also says there is no inconsistency with E=mc^2 but doesn't...

The interaction p + π- → n + π- + π + may proceed by the creation of an intermediate 'particle' or resonance called a rho. This can be detected as a peak in the plot of invariant rest mass energy of the emergent pions versus frequency of pions observed. My question is quite simply, invariant...

If we have two objects A and B appear on the opposite sides of the equator of a planet like Earth with the same mass as Earth. Object A is a neutron star with the mass of the sun and object B is a iron cube with the mass of one gram. Will A or B hit the Earth at the same time or will one hit...

If it takes anywhere between 5,000 to a couple of hundred thousand years (various internet sources have various values) for photons generated in the sun’s core to reach its surface and radiate out, what is the estimated mass equivalence of all these photons making their way out from the core to...

Hi, this problem should be very simple: I have a tank containing water. (going in and out). I want to write the differential equations to see what happen to the temperature and the level of the vessel if the flow of water is not constant. the system should be: $$A \frac {dl} {dt} = F_{in} -...

Homework Statement Find the mass of water that vaporizes when 3.02 kg of mercury at 223 °C is added to 0.347 kg of water at 83.4 °C. Homework Equations Mercury Q = Water Q + Water mL mc∆t= mc∆t + mL The Attempt at a Solution mass of vapor = ((3.02)(140)(223-tfinal) - (4186)(.347)(change in...

Hello, can someone tell me how, or provide me a formula, to calculate the power of the turning shaft? in Nm or Watts, I don't mind. The mass (23Kgr) is turning at stable speed of 100 rpm by external independent force. The shaft is supposed to be on bearings both sides.. I made a picture to save...

The potential energy associated to the interaction between nucleons has its minimum (point of equilibrium) at ##r\sim 0.7 fm##, as showed in the following graph: Nevertheless, there are two facts that are, apparently, in contrast with this: - The average distance between nucleons is...

Supposing that the total mass + energy content of the Big Bang was 100 in energy-equivalent terms. What would we consider its energy-equivalent mass to be today? If the universe is today accelerating and that acceleration is not abating, then (naïvely perhaps...) its (dark-energy) potential...

Consider the pairing term in Weizsäcker formula. Here https://en.wikipedia.org/wiki/Semi-empirical_mass_formula#Pairing_term it is claimed that: I don't understand how Pauli exclusion principle should be the cause of this. This term comes from spin-spin interaction (or "coupling"), but I do not...