# All Questions

0answers
22 views

### Does Compressing Energy over a Multiverse Dimensional Rupre Create Mass? [on hold]

my question is only on a specific method of creating mass through super collapsation of enormous amount of energy in at a singular point or point of singularity.
4answers
400 views

### Why does solid turn to liquid deep in the Earth? [duplicate]

Usually pressure decreases inter-molecular movement thereby keeping the substance in solid state. Given this, why do the earth's crust and mantle, which are both solid, turn into a liquid outer core, ...
4answers
472 views

### Is it possible to reconstruct the Hamiltonian from knowledge of its ground state wave function?

Is it possible to "construct" the Hamiltonian of a system if its ground state wave function (or functional) is known? I understand one should not expect this to be generically true since the ...
0answers
22 views

### Efficient weak form for numerically generating a static magnetic field from arbitrary current distribution (FEM)

This may stray into computational physics, but I'm curious to know if there is some more efficient way for what I am trying to do. Perhaps a better gauge formulation is needed. Consider two ...
2answers
28 views

### Is it possible a linear compression to result in rotational movement? [on hold]

I am looking for a spring or elastic mechanism that I will compress linearly; and when I let it go, it will rotate. Is there such a mechanism or spring?
1answer
14 views

### Sound source localization in cylinder

I am training an animal (let's assume it's a rat) to do sound-source localization in a cylindrical plexiglass chamber that is approximately 30 cm in diameter (see figure). That is, the animal must ...
1answer
47 views

### Simplest way to store a quantum superposition temporarily [on hold]

My understanding of the Schroedinger's Cat experiment is that, while it's an amusing thought experiment, the cat would not actually be in a superposition of states because it's just too massive an ...
2answers
43 views

### Can a binary star system create a stationary black hole?

Research over the last 200 years suggests that half or more of visible stars are part of multiple star systems. I apologise for the number of assumptions in my question but, because of the numbers of ...
1answer
56 views

### Doesn't quantum uncertainty disprove string theory? [duplicate]

String theory states that the oscillations of little strings are responsible for all the particles in and the evolution of the universe. The specific type of particle created by a string depends on ...
0answers
36 views

### Parenthetical tensor notation [on hold]

Just out of curiosity, what does it mean to be a type $(n,m)$ tensor? For instance in the context of special and general relativity, the Minkowski metric $\eta$ is considered a type $(0,2)$ tensor. I ...
1answer
28 views

### The relationship between velocity and radius [on hold]

I have learned that for an object moving in a circle, there must be an inward force acting upon it in order to cause its inward acceleration. This is sometimes referred to as the centripetal force. ...
0answers
20 views

### non newtonian pendulum [on hold]

non newtonian pendulum Description:..Imagine a steel ball is resting on a strip and both the strip and the ball are at a velocity V(1) in the same direction.When the strip underneath changes its ...
1answer
26 views

### Question regarding Kirchoff's loop rule

My problem is that there are n cells connected in parallel which are connected to an external resistor. Now can we use Kirchoff's loop rule to evaluate the current through the resistor by considering ...
0answers
44 views

### Proving that the Boltzmann entropy is equal to the thermodynamic entropy

I've been trying to understand how we can equate the Boltzmann entropy $k_B \ln \Omega$ and the entropy from thermodynamics. I'm following the approach found in the first chapter in Pathria's ...
1answer
14 views

### Why does a soda bottle foam or froth when dropped? [duplicate]

Secondly, if I do drop a soda bottle how long do I have to keep it for it to return to its original state or condition, I.e. safe to open without froth spraying everywhere; or is there some rule of ...
0answers
22 views

### Why are topological phases described by modular tensor categories?

After some reading, I have an inuitive idea what topological phases of matter are. But where is the connection to modular tensor categories? Is there fundamental literature where this is covered?
2answers
992 views

### Could Google scan books without opening them? [on hold]

A few years ago, I read an article about a proposal Google put forward, as part of its paper-to-digital media project, which had the advantage of greatly speeding up the process of scanning text. The ...
0answers
32 views

### How to understand method of images in electrostatics without much maths

How do you explain Method of images for school students without much maths i.e without boundary condition or uniqueness theorem. If it's not possible what are the rules to be followed to solve ...
1answer
25 views

### Cathode ray experiment

How are electrons in a discharge tube emitted from cathode under low pressure and high voltage ? For example in a thermionic emission they are released due to the excess energy they get as heat which ...
4answers
363 views

### Justification of Physical Laws [on hold]

I'm a maths student, and I've studied quite a lot of mathematical physics. All my courses have a similar style - we state the laws of the system, and then deduce the physical consequences as theorems. ...
0answers
16 views

### Simple harmonic motion [on hold]

A body executing shm has 10cm as amplitude and time period is 1.5s. Calculate the time taken by the body to travel a distance 5√3 cm from the mean position. I have used the formula x=asim(wt) And ...
1answer
11 views

### Which weapon can transfer more energy to a projectile: sling or slingshot?

Which weapon can transfer the most energy to a projectile, a sling or slingshot? Each is totally powered by a person, one stores energy in elastic the other kinetically. Which can store and transfer ...
1answer
78 views

### What is the temperature of water at the end of the pipe?

I need to solve the following problem for a practical application. Water, initially at temperature $T_0$, flows with a constant speed $v$ through a PVC tube of length $l$ and diameter $D$. The ...
1answer
35 views

### slippery slope facts of spherical and plane object [on hold]

Imagine a slippery slope and from the top of the slope I threw two object one is spherical stone and the other is plane box. Why the stone would reach the bottom by rolling randomly where the box ...
1answer
24 views

### Corrections to the Bohr energies of Hydrogen [on hold]

Among fine structure, Hyperfine splitting and Lamb shift, why Hyperfine splitting is the smallest while Fine structure is the largest?
0answers
16 views

### Bose-Einstein Condensation at higher critical temperature

The critical temperature $T_{c}$ of a Bose-Einstein Condensate is directly proportional to $n^\frac{2}{3}$, where $n$ is the density of the system which is to be condensed. The current $T_{c}$ for ...
2answers
133 views

### On Newton's discovery of the universal law of gravitation

I'm reading Peter Collier's book on relativity and was on the chapter where he describes how Newton figured out the law for universal gravitation. This is the cannonball referred to in the following ...
1answer
37 views

### Motion of water droplets on airplane window during takeoff

I observed this while on a flight that took of shortly after it had rained, but could not understand why it happened. The windows of the aircraft had drops of water on the outside. As the flight ...
1answer
13 views

### Can we use motor comb with metal sphere of Van de Graaff generator without belt? [on hold]

Can we use motor comb with metal sphere of Van de Graaff generator without belt?
1answer
54 views

### Velocity of satellite to crash into the earth

I was reading through this post today and was very impressed by the response that was given. However, what would have to happen to the velocity in order to collide with the Earth? Velocity of ...
7answers
597 views

### Why is the resistance in a parallel circuit smaller than the resistance in a series circuit?

So I was told in the physics class that the resistance in a parallel circuit is smaller than the resistance in a series circuit. Why does that happen? Is this statement also true for circuits which ...
1answer
39 views

### How is SUN rotating? [on hold]

Is Sun rotating anti clockwise similar to planet Venus or is it continuously changing it rotation ?
0answers
20 views

### What is the position of hydrogen in the periodic table? [migrated]

Hydrogen is not in the first group as it was before and it is now placed above the periodic table? So why is it still categorized as a metal in some books?
0answers
15 views

### PVC Pipe ideal force [on hold]

A longbow is made with a string which is not stretchable and is made with a PVC pipe of radius of around 1 centimeter on the outer and 0.8cm on the inner radius. The pipe is 120 centimeters and the ...
0answers
13 views

### Water Mist Problem? [on hold]

If a 150 USGPM 20 deg.C water in a 40 mm diameter with pressure of 25 bar need to be reduced to 2.5 bar through an orifice: will the water mist manifest?
0answers
22 views

### Pls help me visualise this situation, I'm not able to understand it [on hold]

Find time of flight of projectile thrown horizontally with speed 50m/s from a long inclined plane which makes an angle theta= 45° from horizontal.
1answer
51 views

### What kind of energy does gravity convert to?

I know that energy doesnt disappear rather it just changes forms so that got me thinking to what kinds of energy can gravity be converted to and what is its most common convertion? Im not a ...
2answers
40 views

### Does displacement affect force? [on hold]

I am sorry for being unclear with my previous question. The main topic of the experiment we conducted was about work. As we learned: $W = Fd$ Work, from my understanding, is the product of work and ...
1answer
40 views

### Simple Disk rolling with slipping on a horizontal plane

This is the first time I've encountered this scenario. I want to understand how to handle it. Since the disk is slipping, what would be the work done by the frictional force? What is the ...
2answers
121 views

### Fluorescence and phosphorescence

Fluorescence is where UV light is absorbed then emits visible light right? Is it that you can only see it in the dark whereas phosphorescence is where UV light is absorbed and visible light is ...
2answers
107 views

### Sufficient conditions for a interaction to be classified as weak, strong, …?

Let us say I have been given the equation of a interaction/decay/etc. between particles: $$X+Y\rightarrow A+B$$ Are their any sufficient conditions that we can use to determine the type of interaction ...
0answers
19 views

### What happens to metal when exposed to an electric current for an extended period of time?

I was wondering what happens to the actual metal (copper, aluminum, silver, gold) when electricity is ran through it for a long period of time. Say years like the wire in a house. Does the ...
1answer
20 views

### Does magnetic lines keep moving continuously once the magnetic field is created or they become static? [on hold]

Does magnetic lines keep moving from north pole to south pole outside the magnet and from south to north inside the magnet or they are static once they are created. If the move then why don't the iron ...
0answers
14 views

### Solvation of carbon nanotube in benzene

What is the entropy change upon solvation of carbon nanotube in benzene? I am interested in qualitative understanding of this phenomenon. Thank you.
0answers
8 views

### Head loss and discharge in a pipe system [on hold]

Two reservoirs, whose surface levels differ by 30m, are connected by a pipe O.6m in diam and 3000m long. The pipeline crosses a ridge whose summit is 9m above the level of and 300m distant ...
1answer
50 views

### What happens to the visible light that a substance does not reflect on an atomic level?

Let's say we have a blue, opaque material. If white light was incident on that material, the blue light would be absorbed by electrons and the electrons would transition to a higher energy state, and ...
0answers
44 views

### How the wing creates lift? Why critical angle of attack is 16.5" for a supersonic jet and a kite?

I have seen many references on how the wings create lift, most of them overplaying effect of Bernoulli's rule. But nowhere has there been any consideration given to this important factor: Let's ...
1answer
54 views

### Why is there an upper bound for structure size in the universe?

The Hercules-Corona Borealis Great Wall is often said to be the largest structure in the universe, and to cross a certain upper bound for the size of structures. For instance in this article, a writer ...
1answer
29 views

### Is the energy cost of desalination linear vs salinity? [on hold]

There is a practical limit to how salty water can be and still have a useful potential for desalination. For example, a recent study on the potential for water recover from known sources on Mars ...
2answers
40 views

### What are examples of Couette flow in nature?

What are examples of Couette flow in nature? All I could find are theoretical discussions. It seems to be the flow of viscous fluid between two moving plates. I am imagining slipping on an oily ...

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