2
votes
1answer
46 views

If a liquid is compressed enough, would it become solid?

If a liquid were to be compressed so tensely that the particles had no room to move, would it then become a solid? Also, would the same happen with a gas?
0
votes
0answers
7 views

Looking for full equation for radar cross section of corner reflector

There's a well-known formula for the RCS of a corner reflector (aka corner cube), to wit $ \sigma \varpropto \frac{L^4}{\lambda^2} $ . I've found several sources which cheerfully say "...valid for $ ...
1
vote
0answers
4 views

Increased pressure of Liquid Pitch and Limestone (Bitumen/Asphalt) @ approximately 300 degrees Fahrenheit

If liquid pitch and limestone (20/80 mostly limestone) is pumped (appx. 5 gpm) out of a nozzle that restricts the flow compared to the flow that would be achieved straight out of the pump ( no ...
1
vote
0answers
14 views

PM-IRRAS Equidistant Fringes in Spectrum

What is the cause, and best method to prevent / minimize, fringes in one's FTIR (PM-IRRAS) spectrum on samples deposited on a thin metal film? The fringes look as though they are spaced out by a ...
2
votes
2answers
67 views

If you fall in a black hole, when do you go past the event horizon?

Say I fall into the event horizon of a black hole. As I cross the black hole, I would appear to outside onlookers to freeze in time, and would never move from that point again. In my perspective, time ...
3
votes
2answers
60 views

What's in the empty space between a nucleus and the electrons? [duplicate]

I was thinking the other day about how the empty space in an atom is relatively huge, but I was wondering, is it really empty space? Originally I just assumed it was a vacuum and that was it, but that ...
6
votes
4answers
134 views

Does quantum mechanics imply that particles have no trajectories?

In Classical Mechanics we describe the evolution of a particle giving its trajectory. This is quite natural because it seems a particle must be somewhere and must have some state of motion. In Quantum ...
2
votes
0answers
33 views

Does regularity of distributions have anything to do with definiteness of their product?

Recently I've gone through some literature concerning causal perturbation theory (CPT). As is well known, it deals with UV divergences in QFT by defining products of (operator-valued) distributions ...
3
votes
1answer
20 views

Does the value of Surface tension (the value of the constant) change with a change in surface area?

Surface Tension or ϒ (as in gamma) is a constant value for a particular fluid in fixed conditions. When we increase the surface area of the interface, more molecules pop up at the surface and ...
0
votes
0answers
34 views

Are gauge theories always renormalizable?

Speaking of quantum field theories. Is one of the following implications correct? gauge theory (gauge invariant) => renormalizable renormalizable => gauge theory (gauge invariant) If yes do you ...
1
vote
1answer
28 views

Finding velocity field of spherical bubble in incompressible fluid

I have the following question: A spherical bubble in an incompressible fluid of density $\rho$ has radius $a(t)$. Write down an expression for the velocity field at a radius $R > a$. The pressure ...
1
vote
1answer
65 views

How is “little h” measured in cosmology? The dimensionless parameter from the Hubble constant, H_0

Hubble's law has been well-know for close to a century now. It is written as $v = H_0 d$ where the Hubble constant $H_0$ is the constant of proportionality between recession speed $v$ and distance ...
1
vote
2answers
43 views

Understand the relation of time and the space dimensions of spacetime?

I assume the relation of the three spacial dimensions and the time dimension is handled purely in the mathematical domain, usually. But is there any intuitive description of this relationship, how ...
2
votes
2answers
40 views

Physical reason behind having greater amplitude when driving frequency$ < $ natural frequency than that when driving frequency $>$ natural frequency

This is quoted from A.P.French's Vibrations & Waves: If the driving force is of low frequency relative to the natural frequency, we would expect the particle to move essentially with the ...
0
votes
0answers
17 views

What is strength of an electromagnet at a distance?

I want to levitate a permanent magnet between two electromagnets. My two governing equations are: $$F = \frac{B^{2}A}{{2\mu_{0}}}\tag{1}$$ $$B = \frac{NI\mu}{L}\tag{2}$$ Where $x$ is the distance ...
0
votes
1answer
37 views

How to calculate the weight in en elevator going upwards / downwards?

When the scale shows higher digits in the elevator, how do I calculate the real weight?
0
votes
1answer
20 views

Nozzle vs Orifice Water Jug Draining

why is this happening? Water jug draining So why does the water drain faster when you drain a jug through a funnel compared to the hole you make at the bottom of a jug( the hole is the same size as ...
1
vote
1answer
34 views

Electromagnetic cooling

Heat means stored kinetic energy in matter. Microwave owens and induction heaters works on increasing kinetic energy on matter. Is it possible to make inverse of this heaters like cooler. Can we ...
1
vote
0answers
11 views

statistical property of light reflected from a coarse mirror

This is a problem comes up in my study in correlation reflectometry. I'm wondering if there is a straight-forward way to interpret the phase and amplitude of the reflected light from a perturbed ...
2
votes
0answers
22 views

How to find set point for PID controller for self balancing robot?

I am building a Self balancing robot and needs to tune PID controller to generate PWM signals. My robot chassis is home made and not in perfect alignment. I have placed 6 axis motion sensor on top of ...
0
votes
1answer
31 views

A question about Undamped Vibration [on hold]

A small collar of mass 1-kg is rigidly attached to a 3-kg uniform rod length L = 1 m. Determine the period of small oscillations of the rod when (a) d = 1 m, (b) d = 0.7 m.
0
votes
0answers
21 views

In a system with a decaying magnetic field, is the induced E-field around the wire constant?

Below is an example problem that I know how to solve, particularly when the current is switched off and the magnetic field is allowed to decay. However, in systems typically like these, is it a far ...
1
vote
0answers
10 views

Deformation in the nematic phase of a liquid crystal survived in solid state

Does anyone know if I cool a liquid crystal with a deformed nematic phase quickly it will preserve the deformation in the crystal lattice? I didn't never see that in classical books on liquid ...
1
vote
0answers
31 views

What is the relationship between coherent states and quantum coherence?

What is the relationship between coherent states and quantum coherence? To me coherent states were only talked about in regard to Quantum Harmonic Oscillator, whereas coherence and decoherence on the ...
-1
votes
0answers
17 views

To what distance from the station, at most, we can still listen to that station with the recipient ? [on hold]

In a distance of 5 km from radio transmitting stations broadcast equally in all directions, the size of the magnetic field density is equal to the third 10-11 Vs / m2. What is the power station? The ...
-1
votes
0answers
10 views

What are the driving voltage and internal resistance of the unknown Rx - galvanic cell [on hold]

Driving voltage and internal resistance of galvanic cells is measured by the circuit shown in Fig. The driving voltage of the famous Article Ug = 9 V. its internal resistance Rn = 10 ohms, resistor R ...
0
votes
0answers
22 views

Quark and anti-quark number density [on hold]

Im trying to solve this question but having little luck in doing so. Would appreciate if someone could help me out!
0
votes
0answers
16 views

What is the speed of the panel when the spacing between the plates increases [on hold]

Flat-panel capacitor WITH the surface area of 200 cm2 is connected to the voltage 1000 V. One of the plates we start to move away from a constant force 5.10-4 Newtons. the spacing between the plates ...
2
votes
1answer
34 views

Number of Nodes in energy eigenstates

I have a question from the very basics of Quantum Mechanics.Given this theorem: For the discrete bound-state spectrum of a one-dimensional potential let the allowed energies be $E_1<E_2< ...
1
vote
2answers
40 views

What is the implication of an expanding universe on a small scale?

As a layman I am struggling to understand what effects the fact that the universe itself expands has on distance, density etc. If the universe expands by a factor $k$, does that mean that the ...
3
votes
1answer
46 views

Special relativity kinematics problem

I have this problem in SR kinematics. a spaceship travels near earth at c/2. it shoots off a light-ray at 45deg to its direction of travel (measured in its own ref frame). What is this angle in the ...
1
vote
0answers
15 views

Expectation value in spin-orbit coupling

So I was just trying a question where it asked to find the Energy shift due to a spin-orbit coupling Hamiltonian to first order using perturbation theory. The Hamiltonian is $$H_{LS} = ...
0
votes
0answers
18 views

Why we compare expectations sometimes and sometimes probabilities?

I am reading device independent approach on quantum mechanics from here device independent outlook on quantum mechanics. In here the author introduces local variable theory. Then he give two results. ...
0
votes
0answers
30 views

Would the asymmetric collapse of a star produce a naked singularity?

If this is a duplicate, I will remove it. A few years ago SciAm ran an article based around possible variants of stellar collapse. My apologies, I can't remember much more than their main point, that ...
1
vote
0answers
34 views

Scattering amplitude, link between quantum mechanics and QFT

In quantum mechanics, we can define the scattering amplitude $f_k(\theta)$ for two particles as the magnitude of an outgoing spherical wave. More precisely, the asymptotic behaviour (when ...
0
votes
1answer
51 views

How do compressible fluids behave near a sink?

Imagine there is a large spherical tank of a fluid floating in space. There is a small pipe from the outside to the inside that opens in the center of the spherical tank and lets fluid out at a ...
2
votes
2answers
104 views

Why does the magnitude squared of the wave function give us the probability density? [duplicate]

My question doesn't go much beyond the title: Why does $$\left | \psi \left ( x,t \right ) \right |^{2}$$ give us the probability density of something appearing at a certain location? I understand ...
0
votes
1answer
27 views

Finding the tension in a rope with mass defined per unit length [on hold]

A rope of length L has its mass per unit length λ varies according to the function λ(x)=e^x/L. The rope is pulled by a constant force of 1N on a smooth horizontal surface. Find tension in the rope at ...
1
vote
1answer
41 views

What actually happens when electrons 'collide' with other electrons in a conductor to produce heat in an electrical circuit?

Textbooks describe resistance as involving electrons colliding with other ions in metals, resulting in a heating effect, though how exactly is this achieved? Although I am not required to learn the ...
2
votes
1answer
35 views

Compound map in manifolds

In the description of a manifold, we often start with the mathematical definition that $M=\cup M_i$ and if $m\in M_i \subset M$, where m is a point on the manifold, then it is mapped by a one-to-one ...
0
votes
0answers
17 views

Magnification: Microscopes Telescopes

What is the difference between the way a microscope magnifies say a star and a telescope say a cell? Why is it, that the eyepiece of a telescope magnifies stronger when it is smaller and with a ...
-1
votes
2answers
41 views

What should the length of my wire be in order to get a surface area of 10cm^2?

I would like to make a flat coil out of a steel wire that is 1.22mm in thickness (or 1.22mm in diameter). I wish to make the coil up the wire into a flat disk that has a surface area of 10cm^2. What ...
2
votes
1answer
37 views

Boltzmann equation in cosmology

I have a question about the Boltzmann equation in cosmology. Im trying to understand how this can hold? Where does the logarithmic terms come from? It is explained quite well here ...
0
votes
2answers
29 views

A binary operator required for observing whether the particle is present in a given spatial region

Consider the wave function $\psi(x)$, I want to define an experiment using quantum mechanical rules. The experiment is to find whether the particle is in the region of space (a,b). The observable is ...
1
vote
0answers
24 views

Difference in partition function of Classical and Quantum Ideal gas

First, I have read this question:What is meant by the term "single particle state" There is an analysis going on in my book (Mandle F. Statistical Physics) that has brought me in a ...
1
vote
2answers
43 views

When doping a material, why is As called impurity?

Doping is the act of adding impurities to Group-IV elements to e.g. improve their conductivity. Though it is improving the conductivity, why is it called impurities?
1
vote
1answer
50 views

Representations of Lorentz algebra

It is well known that the Lorentz algebra can be written as two $SU(2)$ algebras. By defining $$N_i=\frac{1}{2}(J_i+iK_i), \qquad N^{\dagger}_i=\frac{1}{2}(J_i-iK_i)$$ we have ...
0
votes
3answers
66 views

in Newtons 3rd law, where does the second body get its energy to react?

A very basic question, and apologies if I have overlooked something obvious. In newtons 3rd law, presumably energy is transfered to the second body from the first body (which itself was subject to an ...
0
votes
0answers
25 views

What do physicists mean with “classical critical behaviour”?

What do physicists mean with "classical critical behaviour"? As far as I am concerned it should be "power law behaviour" of some quantity close to the critical point but I ask here to be sure.
0
votes
1answer
57 views

Has infinity been observed yet?

Has infinity been observed yet? Or in other words. Does infinity actually exist or is it just a concept? Is it just another way of saying very or extremely?

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