# Questions tagged [mass]

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.

2,061 questions
Filter by
Sorted by
Tagged with
123 views

### If mass can be converted to energy than how is it said that energy can't be created?

From the mass-energy equivalence E=m(c*c), it can be seen that energy can be created and it is not converted from one form of energy. Or am I wrong ? Can you explain?
62 views

### Effect of non-zero photon rest mass in optics

If photon has nonzero rest mass, I have inferred that the gauge invariance is broken and the Maxwell's equations change and Klein–Gordon equation comes into picture. What is its effect in optics such ...
95 views

### Questioning whether gravity is strictly attractive. Is there a possibility for repulsion?

My teacher wanted to test our understanding before starting a new topic. The question he gave goes something like this “There are 2 vacuums present here about which there is an abundance of mass ...
79 views

### Schrodinger equation in momentum representation with position-dependent effective mass

I'm trying to convert Schrodinger equation with position-dependent effective mass (PDEM) to momentum representation, and I'm not sure how to apply the kinetic energy operator. In position ...
73 views

### Satellite Motion centripetal force

Once I read in a book that the centripetal force that keeps the satellite in its circular orbit around the Earth is approximately equal to its weight. My question is why the word "approximately" was ...
43 views

### Are the so called force balance drawings for motion systems “counterintuitive”?

Lets take the standard mass-spring-damper system with an external force. Please also see the image. As we all know making mistakes with signs in these questions is a common error. There is even an ...
249 views

### What are the factors affecting torque (in normal cases)?

I know that force and perpendicular displacement are the factors. I want to know the factors like mass of the body and how and why is the force not distributed throughout the body uniformly. ...
110 views

### Is $E=mc^2$ only partially true? [duplicate]

I've obviously seen that $E=mc^2$. But I've also seen that the equation $E^2=(mc^2)^2+(pc)^2$ (where $p$ = momentum) is true. If you square $E=mc^2$, and subtract the result from the other equation, ...
213 views

### Rest mass of the photon [closed]

Why is the rest mass of the photon is taken to be zero? If rest mass of the photon is non zero, then it leads to infinite energy of the photon (by $E=mc^2$ equation) and there is a violation of ...
115 views

### What is the mass of a volume of air? [closed]

Google says 1 cubic meter of air has 1 kg of mass at room temp. This seems like garbage, as if the container is supplying the mass. But if there is no container, it cannot take 1 kg of pressure to ...
101 views

### Are neutrinos just different states of a single particle, in essence?

When Neutrino oscillation phenomenon is analysed quantum mechanically, it is said that, \begin{align} |\nu_e \rangle &= \cos(\theta) | \nu_1 \rangle + \sin(\theta) |\nu_2 \rangle,\\ |\nu_\mu \...
70 views

### Is there only one kind of mass of an object in this world?

There are several kind of forces in the world. Is there only one kind of mass of an object in this world? If so, why?
76 views

### How force is equal to the product of mass and instantaneous acceleration?

$$\vec{F}=m\vec{a}$$ Suppose that an object of some mass was constantly accelerating ($\vec{a} \neq 0$) through sometime interval. With no doubt, the object had an instantaneous acceleration at any ...
66 views

35 views

### Alternative particle types?

If we consider mass and charge to be excitations of independent quantum fields, do they necessarily travel together? Can we have objects with only an excitation on the mass field, and objects with ...
104 views

792 views

### Which weighs more in atmosphere, $1\,{\rm kg}$ of steel or $1\,{\rm kg}$ of feathers?

I'm having a discussion at the moment regarding the mass of $1\,{\rm kg}$ of feathers and $1\,{\rm kg}$ of steel. The person I'm arguing with states that $1\,{\rm kg}$ of feathers will be lighter ...
33 views

### Scaling of mass density

Let distances scale as $L'=kL$, $k$ is the scaling factor. Then spherical volume will scale as $V'=k^3 V$. Say, the sphere is filled with mass with constant density. If we scale the model with ...
175 views

### Farnes, cosmology involving negative mass

I came across a paper recently which seems to be getting a lot of popular press, and a student also emailed me to ask about it: -- Farnes, "A Unifying Theory of Dark Energy and Dark Matter: Negative ...
86 views

### Where do gravitational waves and general relativity coincide? [closed]

In the first ten seconds of this video (https://www.youtube.com/watch?v=iphcyNWFD10) the host says that gravitational waves were the result of two black holes merging. That would seem like there is ...
3k views

### Couldn't we always redefine units so that inertial mass and gravitational mass are equal?

It is a known fact that inertial and gravitational masses are the same thing, and therefore are numerically equal. This is not an obvious thing, since there are even experiments trying to find a ...
44 views

### Why we can know what flavor the neutrino is created but not their mass? [duplicate]

All neutrino knows which of the 3 flavours they must be upon their creation, however their mass becomes uncertain... why is that? isn't mass supposed to tie to which ever flavours like for example an ...
108 views

### Do vibrations increase an object's mass or weight?

does a vibrating object recieve an increase of mass or weight? and if it does, at what frequency or intensity does it need to vibrate at, and what is the rate of increase? is there a formula for it? ...
95 views

### Mass versus rotation Curves

Is there an equation that describes the relationship between the mass of the Galaxy and rotation curve? I found V versus R graphs and equations that describe their relationship (kind of). But I ...
12k views

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

I was given an interesting dilemma today. A co-worker saw me adding a liquid (Diisopropyl ethylamine AKA DIPEA) to a flask filled with another liquid (Tetrahydrofuran AKA THF). I needed to weigh out ...
73 views

### Can we weight dark matter?

We can observe the effect of light as it gets bended in the presence of dark matter, and I wonder how is it possible to measure their mass given that we can't see them and they don't interact with ...