# Tagged Questions

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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### The concept of center of mass behind dropping water from a faucet?

Water, dripping at a constant rate from a faucet, falls to the ground. At any instant there are many drops in the air between the faucet and the ground. Where does the center of mass of the drops ...
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### Asymtotically flat spacetime applicable for spacetimes which are not diffeomorphic to $\mathbb{R}^4$

I wanted to investigate changes on a compact 4-manifold $M$. More specifically it is the K3-surface. I follow a paper by Asselmeyer-Maluga from 2012. The idea there was to make sure that the manifold ...
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### Relativity and the Higgs field

We know very well that as the velocity of an object increases, its relativistic mass also increases because of an increase in its energy which is directly equivalent to mass. We also know that the ...
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### 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 ...
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### Calculating size/weight of the base of a banner to withstand wind load [duplicate]

I want to build what is essentially a banner - a rectangular piece of fabric that will be mounted to a stand and displayed vertically. This object will be outdoors, so the most important factor in it ...
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### Why do we need high energy to explore small dimensions?

I am taking a quantum physics class, and for the life of me, I can not remember why we would need a vast amount of energy to understand the microscopic universe.
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### What is the density and energy of a photon?

As I understand, photons are considered mass-less, which is a necessary condition for moving at the speed of light. However, does that mean their density is 0, as they will occupy some volume. If ...
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### 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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### Current known *lower* bounds to the neutrino masses?

I started a little bit of Googling around the topic, and found very few information. There are mainly upper limits. I found lower limits only to the rest mass differences of the different neutrino ...
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### Which is the lightest thing in this universe? Is that a photon or neutrino?

I hear a lot of people saying that neutrino is the lightest subatomic particle but according to me a photon must be the lightest as nothing can travel faster than light because it gets heavier and ...
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### How to get the accurate relativistic momentum form for photons? [duplicate]

I have studied from Griffiths, the relativistic form of momentum is $$p = \frac{1}{\sqrt{1-\frac{v^2}{c^2}}} m_0v$$ Now when I evaluate the momentum for photon, I just insert $v=c$ and $m_0=0$ and I ...
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### Losing mass in space

So I came across a question while studying laws of motion. Roughly, this is how it goes: There are two astronauts in a space shuttle, who together have mass 200 kg. If by doing exercise, they manage ...
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### Follow up question regarding: Deceleration rate of objects of different mass but the same otherwise

My first question was answered here: Deceleration rate of objects of different mass but the same otherwise . But based on that, here is a follow-up question (I also edited my first post with the ...
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### Deceleration rate of objects of different mass but the same otherwise

Using a tennis ball as an example object, if one ball weighs 1 ounce and the other is 2 ounces, and both are struck at 100 mph on the same trajectory, would there be any difference in the deceleration ...
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### 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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### Why does a large train cause the ground to shake?

I work in a 4 story building that is approx. 150 feet away from a set of train tracks. When a large (40+ car) freight train goes by, the shaking in the building is perceptible. As I've watched the ...
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### Does a black hole have any kind of mass?

Currently in my academics I am studying about the Gravitation. In the chapter I came across a term called the Escape Velocity (It's the velocity of any celestial body which is required by an object to ...
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### Does relativistic mass violate the conservation laws?

When an object's speed increases, its (relativistic) mass increases. Are new atoms created inside the object by its increased speed? or is its "gravitational charge" increased by its increased speed, ...
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### Quick question on derivation of mass of star

How do I show that for a binary star system, if one star has mass $M_s$, speed $V_s$, period $P$, the mass of the other star is given by: $$M_P^3 \approx \frac{V_s^3}{2\pi G} PM_s^2$$ I showed it ...
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### Photons have no mass. So, why does $E = pc$ hold? [duplicate]

It's a somewhat theoretical question. In special relativity, The energy of a photon is given by $E = pc$. But, my argument is that, since photons have no mass, how can they have a momentum $p$? The ...
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### 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 ...
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### The speed limit is with respect to what?

As I understand, an object with mass cannot reach the speed of light because its (relativistic) mass increases "exponentially" as it approaches light speed. So there is a relation between mass and ...
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### kinetic and potential energy

I have 2 cubes where one mass is greater than the other. $M$ and $m$, where $M>m$, and there is a hill that is symmetrical on both sides, and has a friction factor of $k$ between the object and the ...
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### Mass,Energy,Matter

In $E=mc^2$ what type of energy is $E$? For instance, you can find the kinetic energy of an electron by using $\frac{1}{2}mv^2$ but you can also find the energy from $E=mc^2$. How are those two ...
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### Olympic weight lifting bar, plate location affect

I apologize in advance for the rudimentary nature of my question. A perfectly balanced weight lifting bar is loaded with three weight plates on each side. The three plates are 25kg, 10kg and 5kg. ...
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### Does the weight of a computer go up as information is added to it? [duplicate]

This probably sounds really naive. But, a strange discussion came up on Quora about computers possibly weighing more when information is added to them. I tried looking around but couldn't find a ...
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### Compton Wavelength

I have the formula for Compton wavelength: $$\lambda_{c}= \frac{h}{m_{0}c}$$ In this equation, is $m_0$ the mass of the electron that the photon hit? I got online that this might be the photon rest ...
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### Why is spacetime curved by mass but not charge?

It is written everywhere that gravity is curvature of spacetime caused by the mass of the objects or something to the same effect. This raises a question with me: why isn't spacetime curved due to ...
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### What would the gravity be like if Earth and the moon were touching?

What would the gravity be like if Earth and the moon were touching? Assuming the moon keeps its form and doesn't collapse on its own weight, would the area between it and the Earth (point B) have ...
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### Mass eigenstate of neutrinos [duplicate]

Isn't mass a fixed and an intrinsic property of a particle? How can we talk about eigenstates of the mass in the context of neutrinos?
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### If a neutrino has a rest frame, why can't a photon have a rest frame as well?

Concerning Rest Frame Wikipedia states: For example, in the rest frame of a neutrino particle travelling from the Crab Nebula supernova to Earth the supernova occurred in the 11th Century AD ...
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### Does time travel violate conservation of mass/energy? [closed]

Imagine I exist at time $t_1$ and my mass is $m$. At time $t_2$ I time travel back to $t_1$. At time $t_1$ there is now a net increase of mass/energy in the universe by $m$. At time $t_3 = t_2 - x$ ...
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### What Would Negative Mass Do To Spacetime?

It's known that positive mass bends space-time to create a curvature. But if something had negative mass what would it do? Make it flat or like a crest?
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### Can we glue femto-cameras to photons? [closed]

I know its not as easy as saying to glue nano-cameras to photons. Please consider the following extract (related to Heisenberg's Uncertainty principle) from the Modern's abc of Chemistry: ...to ...
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### If tachyons exist, what would they do to spacetime?

Mass (Positive) bends space-time generating gravity. If Tachyons are supposed to have imaginary mass, what would they do to spacetime (if they do exist).
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### Electromagnetic factors affecting inertial mass of a body affect its gravitational mass or not?

We can see that when a charge sphere is at rest & we are to put it in motion with any desired velocity than we will have to apply the same force for a longer time as if it were applied to the ...
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### Equality of masses of particle and antiparticle

Usually we say that equality of masses of particle and antiparticle follows from CPT-theorem. But do we need it for showing this equality? The first method to show that is following. The equation ...
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### Mass of a black hole

I know that if a star collapses into a volume with radius less or equal to the Schwarzschild radius $r_s=\frac{2GM}{c^2}$ then a black hole is created and it has the same mass of the star that gave it ...
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### Visualizing Tension in FBD — Rope With Mass

Asked to find the tension of a point that is halfway up a rope (where the rope has mass), given the system: The solution of the problem (FBD included) is as follows. In this diagram (Tm = tension ...
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### Why do clouds fly? [duplicate]

I know it's probably the most stupid question there is, but why do they fly are the clouds lighter than air? What's keeping those tiny ice structures floating miles about the ground? I've been looking ...
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### What is the meaning behind the neutrino oscillation parameter?

As far as I can tell, there are 6 parameters that describe how a neutrino oscillates: 2 mass squared differences, 3 mixing angles and another parameter I don't understand at all (delta). Thus I have ...
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### Why don't we substitute for $p$ in $E = pc$?

See, the energy of a photon is given out by $E = pc = hv$ why don't we substitute for $p$ in $E ^2= p^2 c^2 + m^2 c^4$ by putting $p = \gamma mv$ and then get a value for $m$ (which will be $0$ for a ...
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### Keep an object at a certain hight, does it require energy? [duplicate]

If i have an object with a defined mass, like a stone, and put it on the shelf it will sit there forever (lets forget all external influences). But if I have to hold up the stone I will eventually ...
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### Speed=mass=time? [closed]

I was wondering why objects gain mass with speed? How can we measure speed if there is no truly stationary point to measure from? And if an object comes to a stand still will it loose its mass? ...
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### The speed of light and unstable matter

Mr.E is on a luxury spaceship travelling about 1/2 the speed of light and finds a cubic lump of unstable matter(attached to a bomb) in his cabin. He of course is an expert with bombs but this device ...
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### How far in meters from the Sun's center is the Earth-Sun center of mass?

Like any set of massive objects separated by distance, the Earth and Sun have a center of mass. How far in meters from the Sun's center is the Earth-Sun center of mass? Just curious? Also what percent ...
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### Measurement of Mass and Momentum of a particle simultaneously

In quantum mechanics can the mass and the linear momentum of a particle be measured precisely or do they commute ?
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### How much weight is lifted from each side? [closed]

I don't know the math to do this, so I am asking here if someone can work this out with all of the details I'm providing. Total mass EST.: 2,400 lbs. Length from front to back: 14 feet 6 inches. ...
I've heard that light can form a curve if they travel near high-mass stars or even a black hole with strong gravity. Which is according to this Newtonian formula $$\large F_{g}=\dfrac{Gm_1m_2}{r^2}.$$...