0
votes
1answer
26 views

Reg position of satellite

Is it possible to put an artificial satellite into an orbit in such a way that it will always remain direct over a city (I mean at any specific place)?
6
votes
0answers
21 views

What is the largest number of bosons placed in a BEC?

What is the record for the largest number of bosons placed in a Bose-Einstein condensate? What are the prospects for how high this might get in the future? EDIT: These guys reported 20 million ...
1
vote
0answers
19 views

Error in standardized mass-energy of deuteron?

There is a problem with data that I've obtained over the internet. Here are the two sources of information from which I'm retrieving my data. NNLC and NIST On NIST, I have read that the mass excess ...
0
votes
0answers
43 views

Good introduction to classical mechanics with math [duplicate]

Right now, I'm reading "Classical Mechanics" by Kibble and Berkshire. Already in chapter 2, I have found a concept being discussed that assumes you have prior knowledge. Specifically, it describes the ...
1
vote
1answer
17 views

Why are unilateral Laplace transforms suitable for causal systems and bilateral aren't?

https://en.wikipedia.org/wiki/Two-sided_Laplace_transform#Causality The above section says that bilateral transforms will not necessarily make sense for causal systems. In the course of advanced ...
0
votes
2answers
59 views

A model that unifies the strong, EM, weak and gravity forces?

Does there exist such a model that explains the force clusters (their origin, relations between them): the strong, EM, weak and gravity forces?
2
votes
0answers
27 views

Is it possible to express various nonlinear motions as straight lines in transformed spacetime?

I am trying to understand simple examples of space-time curvature. Assume for the moment that $c$ is infinite (classical curvature due to Newton's laws). Also, I will only consider 1+1-dimensional ...
1
vote
0answers
25 views

vision problems [on hold]

While picking up a pair of eye glasses dropped by a friend, you notice that they form an inverted image of the background and that the image is stretched horizontally as well. Your friend suffers form ...
0
votes
1answer
26 views

Condition for formation of interference pattern

I recently came across this in a textbook of mine while studying the Young's double slit experiment. It says a condition for the formation of interference pattern is s/S < lambda/d Where s is ...
0
votes
2answers
32 views

Current lagging voltage by more then 90 degrees

According to Wikipedia https://en.wikipedia.org/wiki/Leading_and_lagging_current An alternating current that reaches its maximum up to 90° behind the voltage producing it is said to be lagging. and ...
0
votes
1answer
27 views

Comparing voltages of Parallel and Series circuits

There are two electric circuits. Resistor 1 ($R_1$) connected with resistor 2 ($R_2$) by series circuit $R_1$ connected with $R_2$ in parallel Each of the circuit has battery with emf and the ...
1
vote
2answers
61 views

How do two electrical charged particles know to repel or attract each other?

Now per QED, electrical charges interactions are effected by photons. Suppose you are one of the two charges. How do you know to attract or repel the other charge? In other words, how do you know if ...
2
votes
1answer
28 views

Viscosity and surface tension

Both viscosity and surface tension are dependent on the intermolecular forces between the molecules of the liquid. Supposing from this, shouldn't there be a directly proportional relationship between ...
0
votes
0answers
35 views

Inverse of a 3x3 matrix! I need some help! [migrated]

I have this 3x3 matrix $$E_{ij} = g_{ij} + \bar{\epsilon}_{ijk}z^k$$ and want to derive its inverse. I know that its inverse is given by $$(E^{-1})^{ij} = \frac{1}{1+z^2}(g^{ij} + z^{ij} - ...
0
votes
2answers
55 views

On which basis we think there is something more than just super dense matter in black holes?

Apparently physicists think that there is something inside black holes. Like a new universe or a link between dimension... But for me a black hole is no more than supermassive supercompacted matter. ...
0
votes
1answer
49 views

Will this sail-based moving system work? Why? [duplicate]

So simple: Will this sail-based moving system work? Why?
0
votes
2answers
84 views

Is there a binary black hole system in the middle of the galaxy?

We have observed gravity effects from black holes in the center of galaxies, but galactic centers are so dusty that we can’t tell if it’s one black hole or two black holes in a binary system in there. ...
2
votes
1answer
43 views

Spontaneous symmetry breaking of SHO

Spontaneous symmetry breaking refers to the solution of a system loses some symmetry in its Lagrangian. Consider a Simple Harmonic Oscillator, its lagrangian is time translationally invariant but its ...
2
votes
3answers
47 views

Question of Conservation of Momentum

I think I understand the concept of conservation of momentum in an inelastic collision. However, what if two objects, one being more massive than the other, started out together and then separated ...
0
votes
1answer
9 views

What are the Correlations for the Super-compressability Z factor?

I am studying the course TPG4145 Reservoir fluids in NTNU and specifically the supercompressability factor $Z=\frac{V_{\text{real volume of the system}}}{V_{\text{ideal volume of the system}}}$ for ...
1
vote
1answer
42 views

what is causing gravitational pull in between massive bodies? [duplicate]

what is causing gravitational pull in between massive bodies? according to books, what i learnt is graviton particle & some books are saying quantum field is the cause, so which is causing ...
10
votes
6answers
1k views

What was the need for doing experiments to prove quantum entanglement?

This question comes from someone who is interested in Physics but with no theoretical background. In 1936, EPR presented the thought experiment which later came to be known and quantum entanglement. ...
0
votes
0answers
20 views

Ground influence on 434 MHz radio signal

I have read in a paper that ground acts as reflector for radio signals in 434 MHz band. Why is that the case?
-2
votes
1answer
36 views

Defining the Hamiltonian and obtaining equations of motion for physical system [on hold]

I have a relative simple mechanical system, that is modeled with 3 point masses and 3 links. There is an input force F working in the vertical direction and 2 torques $\tau_1$ and $\tau_2$. All ...
0
votes
0answers
24 views

Gravity at event horizon [duplicate]

To find the gravity at Schwarzschild radius of a black hole, I used the below equations. Assuming escape velocity at event horizon is speed of light c and M is the mass of the black hole $$ v_e = ...
0
votes
0answers
20 views

Does dispersion take place in our eyes? [duplicate]

What do we see if a single ray of white light falls in to our eyes ? Doesn't it undergo dispersion ?
0
votes
5answers
53 views

Temperature to make oceans evaporate [on hold]

The Boiling point of the water is 100 C after that water evaporates. If we are to heat the water of all the oceans combined, what should the temperature be set at, so that all the water gets ...
2
votes
1answer
30 views

How does low entropy in the distant past translate into the observed entropy increases?

One of the explanations of the second law of thermodynamics is that it goes back to the low entropy in the early universe (How do you prove the second law of thermodynamics from statistical ...
3
votes
2answers
70 views

Why scalar function of vector can only depend on norm of vector?

In Field Quantization by Greiner and Reinhardt as well as The Qunatum Theory of Fields by Weinberg, concerning the spectral function, the authors say a scalar function of the four-vector $p^\mu$ can ...
-1
votes
0answers
33 views

Why is the fact that our universe is fine-tuned to life [on hold]

Why is the fact that our universe is fine-tuned to life not convince most people enough that the multiverse is real. we have to choose to believe now since it can't be proved directly forever. I don't ...
0
votes
0answers
14 views

Irreversibility of the nuclear decay process: is there a rigorous proof?

Consider an unstable nucleus that emits an alpha particle. For describing the process we solve the Schrodinger equation using a complex energy, and obtain a Gamow state. The mere fact that we use a ...
1
vote
5answers
326 views

Why do the high frequency waves have the most number of modes?

While reading the Wikipedia page of Ultraviolet Catastrophe, I came across how Rayleigh and Jeans applied the equipartition theorem. They told that each mode must have same energy. Now as the number ...
0
votes
0answers
12 views

to find work from that question kindle give some idea [on hold]

A set of friction less wheels are attached to the bottom of a box, which is then measured and found to have a mass of 6.0 kg. The box is placed on the floor, and a student of Physics uses a brief ...
0
votes
1answer
78 views

Total and partial derivatives in thermodynamics and Maxwell relations

Consider the expression $$dS=\left(\frac{\partial S}{\partial T}\right)_VdT+\left(\frac{\partial S}{\partial V}\right)_TdV$$ I'm trying to understand how to derive an expression for $\left( ...
0
votes
0answers
22 views

Cohen Tannoudji solutions to exercises

Does anyone know where to find the solutions to the exercises of Cohen-Tannoudji's Quantum Mechanics? I am gonna try to do all of them and would like to check.
3
votes
8answers
2k views

Why does the Sun always rise in the East?

Why does the Sun always rise in the East? Earth is rotating on its own axis & also revolves around the Sun, then how come the Sun always rises in the East?
0
votes
2answers
67 views

Lever “paradox”?

Let's say we have a lever with two weights A and B with the same mass overlapping at the midpoint. Suppose they start to separate with each other at the speed of light simultaneously. From our point ...
1
vote
2answers
43 views

How does the Moon stay in orbit?

How does the Moon stay in orbit? The Moon has not reached escape velocity from the Earth, then how does the Moon stays in orbit?
0
votes
0answers
22 views

Diameter of aluminium ring after it expands [on hold]

An aluminium ring has diameter $200.00$ mm at $25.00^0C$. What would be its diameter at $325.00^0C$? $\alpha$ for aluminium is $7.500 \times 10^{-5}K^{-1}$. Thanks for your help.
3
votes
0answers
41 views

Proving $[a_k^\dagger, a_q^\dagger]=0$

I am trying to prove the commutation relations between the creation and annihilation operators in field theory. I was already able to show that $[a_k, a_q^\dagger]=i\delta(k-q)$. I want to show that ...
8
votes
3answers
568 views

Electromagnetic waves should stop while encountering a conducting shell?

I am a high school student who has just started reading elementary electromagnetism and am a completely beginner in this subject. I have read in books that EM waves are nothing but sinusoidal ...
1
vote
2answers
18 views

Understanding a graph of energy conservation with bounded and unbounded motions?

This graph is from the physics undergraduate text "Classical Mechanics by Douglas Gregory". Above this graph was the statement: What I didn't understand is- as stated in the under [*paragraph], ...
0
votes
1answer
25 views

Is it possible to project black light? [duplicate]

A thought passed by me and I wondered if projecting black light was possible. We can make lights with many other colors, but I'm not so sure about black. So, is it possible? Has it been done?
0
votes
0answers
14 views

In hydroelectric power stations, can i use valves in place of turbines? [on hold]

In hydroelectric power stations, can i use valves in place of turbines? by replacing turbines with valves, we can control flow of water, so we can totally handle hydro electric power stations ...
0
votes
2answers
90 views

Why does iron sink in molten iron instead of floating?

Why does iron sink in molten iron whereas ice floats on water? Both are solid states of their own form, so why is one floating and the other sinking?
0
votes
2answers
37 views

What role does the Higgs Field play in the universe?

The Higgs field is known as a physical field that covers the entire universe, giving particles their mass. However, that got me thinking if the Higgs field not only gives mass to other particles, but ...
0
votes
0answers
6 views

current and potentials in conductive sphere with shell

I would appreciate an explanation for calculating the electric potential in this scenario. Central conductive sphere, ends at diameter b, and conductivity $\sigma_1$ Shell (around the central ...
1
vote
4answers
28 views

Why is microwave better than visible light for point to point data communication?

In the electromagnetic spectrum, it appears that the shorter the wave length, the better the bandwidth due to higher frequency. Some communication systems utilize microwave to transmit data to offer ...
1
vote
2answers
20 views

why only surface of water get frozen in polar countries?

why only surface of water get frozen in polar countries? but if i kept glass full of water in fridge then not only surface, whole water turns frozen ,why?
0
votes
0answers
26 views

Pre-Higgs Energy of electron [on hold]

What is the bare energy of, say, the left-chiral component of the electron, without the mass-conferring Higgs interaction? Clarification: A massless photon nevertheless has an associated energy. ...

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