0
votes
0answers
4 views
High and low pressure area and raining
In the high-pressure area it is mostly likely that there is sun. In low pressure area it is mostly likely that rain will occur.
Because of the law that ...
0
votes
0answers
9 views
Internal energy, and heat transfer in isothermal expansion of a gas [closed]
I have this question.
One mole of ideal monatomic gas is confined in a cylinder by a piston and is maintained at constant temperature $T_0$ by thermal contact with a heat reservoir. The gas slowly ...
0
votes
0answers
9 views
Is this an exact differential or not? [migrated]
I have the 1-form
$$dz=2xy\, dx+(x^{2}+2y)\, dy$$
And I want to integrate it from $(x_{1},y_{1})$, to $(x_{2},y_{2})$.
If I'm not drunk, checking mixed partials, I find that $dz$ is an exact ...
0
votes
0answers
13 views
If an area is prone to fog in the mornings, is it less likely to rain?
I live in a city that is very well known for having foggy mornings. Would it be less likely to rain in the morning as a result of this fog?
1
vote
1answer
19 views
What is the electric field in a parallel plate capacitor?
When we find the electric field between the plates of a parallel plate capacitor we assume that the electric field from both plates is $${\bf E}=\frac{\sigma}{2\epsilon_0}\hat{n.}$$ The factor of two ...
0
votes
1answer
23 views
Some Dirac notation unclarities
Q1:
Ok so i have come to a point where i know that $\Psi(r,t)$ which we denote only by $\Psi$ can be represented in a Hilbert space by a vector which we denote $\left|\Psi\right\rangle$. Does this ...
0
votes
0answers
9 views
Error bars for pair-correlation function [migrated]
I have obtained some data from neutron diffraction for some material samples. The "rawest" form of the data is the structure function $S(Q)$.
We can choose a variety of different Q-maxes when ...
1
vote
1answer
36 views
Why the magnetic flux is not zero?
According to Maxwell's equations the magnetic flux over a closed surface must be zero, why in this case does not happen?
Thanks for your help
0
votes
0answers
11 views
Image formed by a spherical ball [closed]
There is an object on one end of a sphere and an image is formed on the other end. I am given the index of refraction,radius and the distance of the image from the center ball. How do I find the ...
2
votes
1answer
25 views
Acceleration due to gravity?
I was looking into orbitals and found something I haven't been able to understand.
http://www.math.ubc.ca/~cass/courses/m309-01a/hunter/satelliteOrbits.html
There is a part on the page which states ...
0
votes
1answer
28 views
Hamiltonion in 2-dimensions?
I am trying to construct a Hamiltonian for a system in 2 dimensions using Matlab.
I am not sure how this Hamiltonian will look like in matrix form.
If somebody can help me visualize this matrix that ...
2
votes
0answers
32 views
Is the preferred basis problem solved?
Once and for all: Is the preferred basis problem in the Everettian Interpretation of QM considered solved by decoherence or not?
THere are a few people who claim that it's not, but it seems the vast ...
0
votes
1answer
34 views
Is there any case where one would use, snap, crackle or pop?
As we all know, if you differentiate distance with reference to time, you get speed, and likewise, differentiating speed you get acceleration. However, if you keep differentiating, to the rate of ...
4
votes
0answers
46 views
Symmetry of the stress tensor
When presenting the stress tensor (say in a non-relativistic context), it is shown to be a tensor in the sense that it is a linear vector transformation: it operates on a vector $n$ (the normal to a ...
2
votes
1answer
73 views
Why is the temperature zero in the ground state?
This is probably a simple question: I see this claims in many books, but I can't figure a reason why this is true.
So my question is why this claim is true:
"If we know that the system is in the ...
0
votes
0answers
12 views
Spring damper model does not work very well [migrated]
I'm trying to model a spring damper system from a tutorial that I've found on this site.
If I use the exact same parameters as the ones in the tutorial the system is not stable. I've downloaded the ...
0
votes
1answer
22 views
Polarization of Light
How do materials polarize light? I know that they polarize light in the same plane, but light has two perpendicular directions with the two fiels, so which direction is reflected and why?
And if ...
0
votes
1answer
26 views
Refraction of light and frequency dependence
Why do higher frequency waves refract more, both ocean waves and light waves? Also why is energy stored in the frequency as opposed to the wavelength.
-5
votes
0answers
61 views
Criticism of String Theory by other string theorists [closed]
*EDIT: Due to policy I will edit this into a question:
Do you know any string theorist that have criticized string theory and if so please could you give me references? thanks.
End of EDIT. ...
0
votes
1answer
27 views
Pulley system with rope
Two masses $m_1$ and $m_2$ are connected through a weighty, uniform and an unstretchable rope of length $L$. The surface is frictionless. Masses of the objects are $m_1=m$, $m_2=\frac{2}{3}m$, mass ...
0
votes
0answers
13 views
Potential E alternation
Considering a permanent magnet moving in a trajectory perpendicular to a straight wire of a given lenght, in a way that the magnet expose always the north face towards the wire, no matter the ...
8
votes
1answer
80 views
Is the fine-structure constant a parameter of the standard model?
According to the wikipedia entry on the fine-structure constant:
In fact, α is one of the about 20 empirical parameters in the Standard Model of particle physics, whose value is not determined ...
0
votes
2answers
28 views
Electric power transmission
If we want to transmit electic current for a long distance, we must minimize a heat that releases because of the resistanse. We cannot make a cable wide because it is expensive and it will be massive. ...
3
votes
0answers
23 views
Best current bounds on nonconservation of momentum?
It's not straightforward to test conservation of momentum experimentally, and many experiments that seem like tests really aren't. For example, in a Newtonian system of identical particles that ...
1
vote
0answers
37 views
Superconductivity
What is the correct explanation of why superconductivity occurs in metals when they are cooled to a temperature below $T_c$?
My textbook has the following explanation:
Superconductivity is the ...
2
votes
1answer
27 views
Help Understanding Non-conservative Fields
While watching a video lecture I became uncomfortable with the results, which begin around minuite 35. The professor draws an electric circuit with a 1V batter, and two resistors (1ohm and 9 ohms). He ...
2
votes
2answers
92 views
Do generators belong to the Lie group or the Lie algebra?
In Physics papers, would it be correct to say that when there is mention of generators, they really mean the generators of the Lie algebra rather than generators of the Lie group? For example I've ...
0
votes
0answers
13 views
Why is planar geometry preferred to observe ordinary Hall effect?
In the Physics Today article by Avron et.al. "A Topological Look at the Quantum Hall Effect" Physics Today (2003) it is suggested that to observe ordinary Hall effect, planar geometry is preferred to ...
3
votes
2answers
42 views
Why are some jenga pieces easier to remove than others?
Jenga is a game place with wooden blocks stacked on top of one another in an alternating pattern. Players take turns removing blocks from any layer and placing them on top.
As the game progresses ...
1
vote
0answers
19 views
Solution of multiple materials
Introduction
I'm trying to make some strawberry liqueur. The recipe I got says I should put alcohol, strawberries and sugar in a bowl and leave it soaking for 4-5 weeks. I read that making liqueur is ...
0
votes
0answers
29 views
What is the result of applying a fourier transform n times to a distribution?
For a function applying the fourier transform twice is equivalent to the parity transformation, applying it three times is the same as applying the inverse of the fourier transform, and applying four ...
3
votes
2answers
48 views
intuition contradicting answer for calculating pressure
I have a cylindrical container say of some base area $A$. The atmospheric pressure is $P_0$. The cylinder is moved at an acceleration $a$ horizontally right. I need to find which base would have to ...
0
votes
0answers
16 views
Calculate the electric current in the given circuit when (a) Key K is open [closed]
Calculate the electric current in the given circuit when (a) Key K is open.
(b) Key K is closed.
!]each resistors of 6 ohm 1
-2
votes
0answers
27 views
The Hartree solution of two harmonic oscillator coupled by potential $V \propto ({\bf r}_1-{\bf r}_2)^2$ [closed]
$H={\bf p}_1^2+{\bf p}_2^2+{\bf r}_1^2+{\bf r}_2^2+x({\bf r}_1-{\bf r}_2)^2$.
$x$ is the coupling factor.
0
votes
1answer
83 views
can be exist the negative mass? [duplicate]
I'm not sure about this but I guess there must be negative masses in the universe because of the symmetry. If the gravity is one of the main forces in nature it must has negatives mass to be able to ...
1
vote
1answer
26 views
What is the effect of humidity in temperature?
Suppose we have a building in an area with weather conditions $W_t$ at time $t$, and suppose we could change the relative humidity $\phi_t \in W_t$. Would the change in relative humidity $\phi_t$ have ...
0
votes
0answers
17 views
Counting the modes of the vector potential in a coulomb gauge
With a view to quantising the EM field, consider a classical free field in the absence of charge and currents, we can take a coulomb gauge, $\phi=0, \partial_kA_k=0$. The physical fields in terms of ...
2
votes
2answers
44 views
Is it possible to determine the state or values of something without measuring it
To give context to this question, I am currently looking into non-locality / hidden variables / Bell's Theorem, EPR / etc.
I've noticed the assertion that the values / state of something when ...
0
votes
1answer
39 views
if a simple pendulum is dropped in a elevator with a acceleration greater than acceleration due to gravity then what will be its frequency
if a simple pendulum is dropped in a elevator with a acceleration greater than acceleration due to gravity then what will be its frequency ? We know time period depends on frequency.
-2
votes
1answer
32 views
Resistance of a copper wire [closed]
Resistance of a copper wire is 20ohm. If the diameter of the wire is 5mm and length 1ohm. Find the resistivity of the copper.
0
votes
0answers
15 views
Easy to do experiments that clearly show outstanding properties of graphene
By chance we received for free some monolayer graphene sheets (20 cm x 20 cm) and mixed coper-graphene wires at our University. I would like to prepare some very easy to do experiments for the ...
0
votes
0answers
31 views
Derivation of Dirac equation using the Lagrangian density for Dirac field
How can I find Dirac equation using the Lagrangian density for Dirac field?
0
votes
0answers
13 views
Software for electric schemes [migrated]
I am looking for an open source software for creating electric schemes. Could you, please, recommend your favorite programs? Also, it will be better if your programm can do other schemes (for ...
0
votes
1answer
50 views
Why is the Heisenberg Uncertainty Principle not obvious give the conservation of mass- energy?
A photons energy is given by $E=h *f$ and momentum $p=E/c$ (spin?) but the photon has no (rest) mass! Therefore it is the ultimate probing tool for looking at any mass position and velocity because ...
4
votes
1answer
44 views
T-Duality between Type HE String theory and Type HO string theory
My question is regarding T-Duality between the 2 Type H string theories.
I know that the Type II String theories are T-dual to each other because T-Duality changes the sign of the Gamma Matrix so
...
0
votes
2answers
46 views
Momentum, Impulse and Newton's Second Law of Motion
Newton formulated his Second Law as such:
$$\sum{\vec{F}} = \frac{\delta \vec{p}}{\delta t}$$
and of course, $\vec{p} = m \vec{v}$.
Why is it that if the net force $\sum \vec{F}$ is constant (which ...
6
votes
4answers
131 views
In coordinate-free relativity, how do we define a vector?
Relativity can be developed without coordinates: Laurent 1994 (SR), Winitzski 2007 (GR).
I would normally define a vector by its transformation properties: it's something whose components change ...
0
votes
1answer
32 views
Photo of reflection in magnifying mirror shows normal magnification. Why?
I just took a picture of myself in one of those magnifying shaving mirrors and in the photo I am unmagnified! Why is this?
3
votes
1answer
64 views
Can Earth's Magnetic Field Create Electricity?
If the earth has a magnetic field, can it, in theory, be run through a conductive metal coil to create electricity?
1
vote
2answers
72 views
Can we measure “wavefunction” of quantum particles?
We know that there is uncertainty principle, so question: can we ever measure wavefunction of particles? I do not think this is possible, but I am not sure. I guess that everything is probabilistic. ...
