# Tag Info

Accepted

### Rest Mass Energy

In physics today, mass always refers to rest mass. When referring to other types of mass, such as "relativistic mass" or "invariant mass," one always adds an extra qualifier to be ...
• 26.2k

### Rest Mass Energy

The problem with asking for an intuitive explanation is that intuition is not an objective feature of an explanation. Intuition is something that is personal and it is developed individually from ...
• 102k
1 vote

### How does Diagonalizing Mass Terms Affect the Lagrangian?

This is a response to the first part of your question, not related to the neutrino physics specifically. Suppose we start with a generic Lagrangian with $N$ scalar fields where both the kinetic and ...
• 49.7k
1 vote
Accepted

### How is the mass distributed in ordinary matter?

It is correct that the current light quark masses contribute only about 1% of the nucleon mass, and the main contribution is coming from the strong interaction. How one decomposes this contribution to ...

### What does Density really mean?

There is no distinction between gravitational and inertial mass therefore, mass is a measure of how much matter there is. In this sense, density is a measure of how compressed or rarefied the matter ...
• 4,299
1 vote

### Confusion about acceleration when pulling a massively long object in space

When I was in high school, my physics teacher used to use a mouse and an elephant for these kinds of questions. What happens if you push on a mouse? What happens if you push on an elephant? First ...
• 39.5k
1 vote

### Confusion about acceleration when pulling a massively long object in space

If there is just you and the object in deep space, then the motion of the centre of mass of the combined system of you and the object is not affected by your pull (with regards to the combined system ...
• 55.4k

### Do the weights of two liquids not add when mixed?

You need to bake more ðŸ˜Š Go scoop a cup of flour and put it on a zeroâ€™d scale. Record the measurement. Now do it again. And again. You will get all different readings. And this is why in most European ...

### Gravitons with negative mass?

A particle with a negative mass (meaning, a mass lower than the energy of the vacuum) would be disastrous. The vacuum would be unstable to decay into a state with an arbitrary number of negative mass ...
• 49.7k

### Is the mass of curved space, additional mass?

Now I have heard there is an energy associated with the curvature of space. If so, it will have a mass equivalent. Are you thinking of quantum fluctuations in the vaccum? If so, it is believed that ...
• 101

### Is the mass of curved space, additional mass?

You can think of it as potential energy, but there is a caveat: this mass/energy is not localized. You can't say the mass is here or there, because you can't write a stress-energy-momentum tensor for ...
• 21.1k

### Question about relativistic mass and momentum transfer of Light

The best way to reconcile inertia in relativity is to not use inertia, which means not using the relativistic mass $$m\rightarrow \gamma m$$, (I won't even use as equals sign and assign a ...
• 34.3k

### Question about relativistic mass and momentum transfer of Light

How can we reconcile the concept of inertia, typically associated with mass Every Newtonian invocation of mass is actually an invocation of energy. Inertia is not due to mass. It is due to energy, ...

### Question about relativistic mass and momentum transfer of Light

You may choose to define the photon mass as "relativistic mass", $m=E/c^2$ (concrete, old school), or "invariant mass", $m=0$ for a free photon (abstract, fashionable). In either ...
• 21.2k

### Question about relativistic mass and momentum transfer of Light

I do not really see the problem. Just don't think about a photon as a massive ball. Photons are massless particles but have momentum ($p=\hbar k$) which can be transfered. See the principle behind ...

### Investigating the stability of a wooden block

Another explanation I have come up with, is that the edge of the block that the strip is over, acts as the pivot for the mass $m$ This is the correct explanation. If the block (or the bench that it ...
• 55.4k

• 4,242
1 vote

### Centre of mass and reduced mass in classical mechanic

In the two-body problem for two bodies whose position is represented by two position vectors ${\bf r}_1$ and ${\bf r}_2$, it is helpful to rewrite the equations of motion (it doesn't matter if ...

### Is it possible that the mass of a black hole is located at the event horizon?

Is it possible that the mass of a black hole is located at the event horizon? Yes, but not in the sense you mean it. Objects fall into the black hole without slowing. But the light from them has a ...
1 vote

### How do mass and velocity relate to momentum?

Momentum is a measure of the "quantity" of motion there is in a system. It is oriented and proportional to velocity (obviously!). It is also proportional to the amount of matter in motion, ...
• 41

### How do mass and velocity relate to momentum?

I think a better description for momentum is, how much "oomph" an object has. A non moving object clearly has zero oomph. A heavier(faster) object has more important than a lighter(slower) ...
• 1,304
1 vote

### How do mass and velocity relate to momentum?

A force induces a change in momentum. Because momentum is mass multiplied by velocity, that basically means that the faster an object is, or the more mass it has, then the larger the momentum and ...
The pendulum will librate with the proper angular frequency $\omega_{\rm prop} =\sqrt{a_{\rm prop}/l}$, where $a_{\rm prop}$ is the proper acceleration of the rocket hovering above the horizon, and \$...