1
vote
0answers
63 views

Is it possible to determine maximum frequency of a disc using a relative circumference?

On Wikipedia there is an article that shows how to calculate the relativistic effects on a rigid spinning disc, I am referencing the formula under the "Ehrenfest's argument" section in the link. The ...
2
votes
1answer
26 views

Effectiveness of phase-change materials vs water for heat storage?

I'm trying to understand the benefit of specialized phase-change materials vs. water for absorbing heat in a home during the day. It's my understanding that selecting phase-change materials whose ...
-6
votes
1answer
42 views

Can velocity be negative? [on hold]

In free fall I use the formula V=g*t and g is negative(-9.8m/s^2). It gives me negative.
5
votes
1answer
41 views

Why do electrically conductive materials tend to be thermally conductive?

It's hard finding substances that are good insulators of one and conductive of the other. Why the correlation? And why do some materials not have this correlation?
-5
votes
0answers
19 views

Calculate Pendulum force [on hold]

I would like to calculate the impact force of a free fall 16kg Pendulum ball hitting the wall at 1.5m away. Please help. Thanks
2
votes
2answers
64 views

Do any two points in Minkowski spacetime determine a unique line?

Any two points in a Euclidean space determine a unique line, but I wasn't sure if this result generalized to Minkowski spacetime given that the latter is not a Euclidean 4-space, but is, instead, a ...
3
votes
1answer
54 views

Collision between a “spring” and a particle

I am currently attempting to create a simple 2D physics engine, and I just need to know how to solve a certain collision. I have particles, and between any two particles, springs can be connected. ...
1
vote
1answer
67 views

Why is quark flavor just a SU(N) group?

In the standard model one has U(1) for electromagnetism, SU(2) for the weak sector and SU(3) for the color sector. One could say that in the quark part of the fermions, there are $$ ...
0
votes
2answers
78 views

What is entanglement really about? [on hold]

I am a beginner in this field, I am trying to understand the basics of Quantum Mechanics, I want straightforward answers to few questions on entangled photon/electron: 1- What entangled photons ...
0
votes
1answer
22 views

Probability to measure momentum of a certain range (eigenfunctions and such)

At a certain point in time a particle of mass $m$ has the corresponding function (function of $x$) $$\psi(x)=\begin{cases}Nx \exp[-bx]~~&\text{for}& x\geq 0 \\ 0 ~~&\text{for}& ...
-1
votes
1answer
20 views

External and internal resistance to airflow

If an aircraft was travelling at 100mph an hole was opened to allow 100mph into the cabin,then the airflow is feed into an amplifier like a ramjet and the airflow out of the ramjet was increased to ...
2
votes
2answers
22 views

Should static electricity affect a Crookes radiometer?

I've been playing around with a Crookes radiometer for fun and I happened across something I can't figure out. I know the fundamentals of the radiometer (e.g. partial vacuum, thermodynamics, etc.), ...
0
votes
0answers
34 views

Particle Under Constant Acceleration Problem [on hold]

A car travelling at a constant speed of $45.0\:\mathrm{m/s}$ passes a trooper on a motorcycle hidden behind a billboard. One second after the speeding car passes the billboard, the trooper sets out ...
2
votes
1answer
41 views

How to calculate number of degenerate states?

For example if we need to get number of degenerate states for a particle confined in a 3D box that have energy $$E=41\frac{\pi ^2 \bar{h}^2}{2m_e L^2}$$ I know that $$E=\frac{n^2 \pi ^2 \bar{h}^2}{2 ...
0
votes
0answers
38 views

Schrödinger Equation (with finite potential outside well) [on hold]

Derive the eigenvalue conditions of the eigenenergy values of the bound states of a particle of mass m in a one-dimensional potential well. $V(x)=\begin{cases} -V_0 ~&\text{for}& ...
0
votes
2answers
30 views

Determination of the electric field of charged object using Gauss's law

when we determine the electric field of a charged rod of infinite length,we consider a circular cylinder to be the gaussian surface for convenience.In the case of a charged sheet we choose the ...
0
votes
0answers
8 views

Standard Minimal Reference Set of Poroelastic Parameters

I am coding a poroelastic reservoir simulator which requires the input of poroelastic parameters of the reservoir rocks. Detournay and Cheng, "Fundamentals of Poroelasticity" (1993) state that: ...
-3
votes
1answer
61 views

Is there one wavefunction per field? [on hold]

Is the big picture of quantum field theory that: There are fields (EM, electron, Higgs, gravity, etc.) A field can be described by a wavefunction indicating the probability density of 1 or more ...
5
votes
1answer
59 views

Coupling a spinor field to a preexisting scalar field?

So I'm not a physicist, but I'm thinking about a mathematical problem where I think physical insight might be useful. We're working on a Riemannian manifold $(M,g)$ (positive definite metric) with a ...
-5
votes
0answers
31 views

why was necessary the discovered of electromagnetism? [on hold]

Need to know much more for the necessity of electromagnetism. http://www.ck12.org/physical-science/Discovery-of-Electromagnetism-in-Physical-Science/lesson/Discovery-of-Electromagnetism-MS-PS/
0
votes
1answer
61 views

Springs, elastic potential energy, kinetic energy

If a ball with some kinetic energy collides with a spring, the ball doesn't lose its kinetic energy in an instant, right? it loses kinetic energy as the spring gains potential elastic energy. Right? ...
0
votes
0answers
36 views

Eigenstates of 2D harmonic oscillator in a constant magnetic field

I want to find the eigenstates of the 2D harmonic oscillator in a constant magnetic field $\vec B = \vec B(x,y)$. My Hamiltonian reads $H_0 = H_{xy} + H_z$ where $H_{xy}$, is the hamiltonian of the ...
-4
votes
0answers
25 views

Experiment to determine the specific heats of a gas using a resistance heater [on hold]

Can anyone explain briefly how this experiment will be conducted and what measurements i need to take and record?? i need a brief idea to start doing it. Can anyone here pls help me??
-1
votes
0answers
42 views

Vacuum chamber in a space rocket? [on hold]

FYI I am a complete noob in the field of rocket design. Question: Why don't space rockets that take off vertically from the ground have a vacuum chamber in the rocket during takeoff? Also, is the ...
0
votes
1answer
57 views

Why do TM and TE modes coexist in glass fiber?

I have read that TM (transverse magnetic) and TE (transverse electric) modes of the electromagnetic field of light travelling in a glass optic fiber cable coexist. I want to know the precise ...
-2
votes
2answers
53 views

Force at the centre of gravity [on hold]

If we somehow apply a force direct to the center of gravity (existing inside an object ) , does it increase the angular velocity of a rotating object as it does in normal case ?
-5
votes
2answers
76 views

Soft question - Why do theoretical physics ? and what is its motivation? [on hold]

Okay some background - I am a Theoretical physics graduate student (and i would go even further calling myself a math person) and quite recently I have been into this question and am finding it hard ...
0
votes
0answers
45 views

Uncertainty principle ( tau lepton) [on hold]

A tau lepton mass's is $1.8$ $\frac{GeV}{c^{2}}$ and has a life time of $0.3ps$. Find $\frac{\Delta m}{m}$. My first idea was calculate the energy uncertainty, then I tried to find $\Delta m$ but, I ...
1
vote
1answer
38 views

Interaction Potential for Damped Driven Pendulum

I'm trying to use the velocity Verlet integrator to simulate a damped driven pendulum (with unit mass) described by $\ddot{\phi}+\gamma \dot{\phi}+\omega_0^2 sin\phi=Acos(\Omega t)$ The Verlet ...
-2
votes
1answer
46 views

evidence for wavenature of particles from deBroglie wavelength [on hold]

Doing a search on electron diffraction this, for example http://hyperphysics.phy-astr.gsu.edu/hbase/quantum/davger2.html , the evidence does not look overwhelming for the significance of the deBroglie ...
-1
votes
1answer
34 views

Dual nature of matter and electromagnetic radiations [duplicate]

I haven't completely understood the dual nature of matter and electromagnetic radiation. If all matter has wave nature and and all waves have particle nature then how will one distinguish between ...
-4
votes
0answers
28 views

What is the speed of time between bodies? [on hold]

I'm guessing the speed of time is 1 sec per sec on the surface of earth? If so, what is the speed of time on the surface of the sun? What is the speed of time 100,000 miles off the surface of earth? ...
0
votes
0answers
16 views

Bandwidth of second-harmonic generated (SHG) field for pulse excitation

I wanted to know the bandwidth of the second-harmonic field generated from type-I SHG process when excited with a pulse of bandwidth $\Gamma$. In this lecture notes, the author calculates the ...
-2
votes
1answer
29 views

Dropping a bolt in an accelerated lift [on hold]

Here's the problem given to me: A lift starts from rest with an acceleration of $a$. At the time it starts, a bolt is dropped from the top of the lift. If the height of the lift is $h$, find ...
-4
votes
0answers
16 views

Intensity of antenna pulsed pattern? [on hold]

Let say we have an antenna driven in a way that produces an E field pattern in particular direction that has the form of short pulses $E(t)$ delayed and phase shifted: $$ E_{tot}(t) = \cdots + ...
-1
votes
0answers
20 views

A bar magnet is brought close to, but does not touch, a paper clip [on hold]

The paper clip moves toward the magnet. What does this observation show about the field associated with the bar magnet?
0
votes
0answers
19 views

Derivation of effective mass equation in carbon nanotubes

I am trying to reproduce the calculations in the paper here by Ando and Nakanishi and am already stuck on equation 1. It is stated that in the vicinity of $\epsilon=0$ the amplitude of the ...
2
votes
2answers
70 views

Newton's Cradle: why does it stay symmetric? [duplicate]

How is it that always the same number of balls leave at the other end in Newton's cradle. I understand that the momentum needs to be conserved, but as momentum is defined as p=m*v couldn't you have a ...
-3
votes
0answers
20 views

PARALLEL COMBINATION OF SUPERCONDUCTORS AND RESISTORS [duplicate]

........................please reply to the question above in the picture. I have tried a lot and have thought about it for a long time. Please help me and answer in simple words. AND I REQUEST NOT ...
-6
votes
0answers
34 views

Could be calculated radius of proton from its mass [on hold]

$r_p m_p = 2 h / π c$ , $r_p = 8,4123 E-16$ m or $r_p = 2L_p^2 c^2 / G m_p = 8,4123 E-16$ m close enough to experimentally determined radius: $99,96\%$ references :DOI: 10.1126/science.1230016 ...
-1
votes
0answers
21 views

Particles A and B have different masses and net electric charges [on hold]

is the size of the electric force on particle A due to particle B the same as that on B due to A??
0
votes
1answer
35 views

Why do LIGO use a quarter wavelength for detecting gravitational waves?

I have already researched into this and I am left slightly confused still. I have gathered that the use of a quarter wavelength is to turn a linearly polarised wave into a circularly polarised wave. ...
2
votes
1answer
34 views

High surface area for given volume [on hold]

What can be a example similar to mathematical Koch flake that could be found in nature... where for a given enclosed volume its surface area is indefinitely large?
8
votes
1answer
53 views

Measuring tides in a swimming pool

The tidal range of a perfectly fluid inertialess ocean on the Earth (taking into account lunar tides only) is approximately half a metre: this is the range between "high" and "low" points of an ...
7
votes
1answer
54 views

Does spontaneous emission count as a measurement?

It is my understanding that in the density matrix formalism for open quantum systems the environment-induced measurements/collapses/projections are accounted for by the Lindblad superoperator (from ...
2
votes
2answers
56 views

Are these capacitors parallel or in series?

I am a bit confused. The authors say these conductors are parallel when the switch is on. But to me it looks like they are in series since the handle is insulating. How can you explain that they are ...
-3
votes
0answers
32 views

What exactly is meant by Moment of inertia of a body? [on hold]

Physical significance of Moment of inertia, not just the formula. any help
0
votes
0answers
40 views

Physical Significance of Wigner Equation, Wigner Current

I am Currently doing a reading about Wigner function in Quantum optics, I learnt that the Wigner function maps the Quantum mechanical operators to phase space functions in phase space, so we can talk ...
0
votes
1answer
35 views

“Nearest” Perpetuum Mobile? [on hold]

We all know the concept behind Perpetuum Mobile. Instead of trying to grasp the impossible, how near could we actually approach the general idea? By this I mean to look at the "apparent perpetual ...
0
votes
0answers
27 views

First order time-independent perturbation theory: How to practically calculate the perturbed wave-function

This is one of the problems that draws the line between academically learning something, and having to use it. While I learned the formulas relevant to this, I just want to make sure I'm using them ...

15 30 50 per page