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1answer
18 views

Cylinder rolling down an incline in a vacuum

Say you set up an experiment with an inclined plane, and a cylinder rolling down the plane. Let's also let the experiment happen in a vacuum, such that there is no air friction. However, let there be ...
0
votes
3answers
42 views

How the ladder will slip if the wall and ground were to be smooth?

If I have a situation like this Where my blue thing is wall and the yellow thing is the ground. If both were to be smooth then they will exert a contact force only normal to them which I have ...
0
votes
1answer
82 views

In quantum mechanics, which concept caters for light rays?

If photon wavefunctions are omnidirectional and don't have a definite size, how comes those from the Sun don't all collapse on Mercury and some do actually reach Earth ? I understand that ...
10
votes
7answers
2k views

If an object moving in a circle experiences centripetal force, then doesn't it also experience centrifugal force, because of Newton's third law?

When an object moves in a circle, there's an acceleration towards the center of the circle, the centripetal acceleration, which also gives us the centrifugal force (since $F = ma$ is the equation for ...
-1
votes
0answers
17 views

How to go about solving this question? [on hold]

This question is from first order circuit and under the heading of source free RL circuit (https://i.stack.imgur.com/SY1L6.jpg)
0
votes
1answer
26 views

When assembly of atoms is influenced by EM wave only few of them get excited not all? Why?

In laser when assembly of atoms is influenced by em wave, only few of the atoms get excited not all? why it happens
-6
votes
0answers
60 views

Does shining a neutron beam with Xrays/photons of pair production potential > 1.022MeV accelerate neutron decay? [on hold]

Confirmed experimental data is the looked after answer. Pure, simple , straight forward. edit: beamed or bottled/cold neutrons, either works.
0
votes
0answers
37 views

At what angle is a rock thrown if the maximum height of its flight is equal to its horizontal range R? [on hold]

A rock is thrown upward from level ground in such a way that the maximum height of its flight is equal to its horizontal range R. At what angle $\theta$ is the rock thrown? I used range formula $R=\...
1
vote
0answers
37 views

Double-slit experiment with erasing all the collected data

The question concerns the double-slit experiment with collecting the data to register through which of the slits every single photon has passed. As I understand, in this case, when the photons are ...
1
vote
1answer
41 views

How come that rough mouse pads provide less friction?

Gaming mice have very smooth bottoms, but gaming mouse pads have a very rough surface, much more than regular mouse pads. How can it be that a smooth surface on a rough surface have less friction ...
0
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0answers
16 views

How to find the angular velocity of a rotating frame with respect to an inertial frame? [on hold]

In the example below, the author derives the angular velocity of the xyz frame with respect to non-rotating earth. I failed to understand how he derived the angular velocity? What does the author mean ...
0
votes
2answers
54 views

Is the Moon's rotation affected by Earth's?

There is a lot written on the moon affecting the Earth's rotation but not so much the other way around. I know that moon has its own rotation: Tidal locking is the phenomenon by which a body has ...
0
votes
1answer
31 views

Momentum in complex scalar field

Consider a complex scalar field $\psi(x)$ with Lagrangian density $$ \mathcal{L} = \partial_\mu\psi^* \partial^\mu\psi - M^2\psi^*\psi. $$ Expand the complex field operator as a sum $$ \psi = \int \...
0
votes
1answer
43 views

Do quantum effects of macroscopic objects dissapear because of decoherence or because large objects have small wavelenghts, or both?

I’ve read that the wavelength of macroscopic objects is so small that it’s effects are negligible so the object can be described with classical physics, and that decoherence causes quantum effects to ...
1
vote
1answer
24 views

Using height to calculate Pressure (independent variable) and Flow rate (dependent variable)?

The investigation is experimentally verifying Poiseuille's equation. The independent variable is the changing pressure and the dependent variable is flow rate. My experiment plan is having a simple ...
-4
votes
0answers
23 views

If one “sidereal” day equals 23 hours, 56 minutes, and 4 seconds, what does it look like in decimal form? [on hold]

Will somebody give me the exact decimal form of 23 hours, 56 minutes and 4 seconds?
-5
votes
0answers
29 views

I'm not a physician, What about the chance to make a radiotelescope of today communicate with a radiotelescope of the past or of the future? [on hold]

I'm not a physician, What about the chance to make a radiotelescope of today communicate with a radiotelescope of the past or of the future ? The speed of light is k bigger than the speed of the ...
3
votes
2answers
76 views

Physically intuitive explanation for Hamiltonian of charged particle in EM field

I've recently been looking at the quantum mechanical description of a charged particle in an EM field and have come across this classical Hamiltonian: $$H = \cfrac{(\mathbf p - q\mathbf A)^2}{2m} + q\...
1
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0answers
39 views

Can we hold atomic hydrogen for a long time? [on hold]

If we take atomic hydrogen with similar spin together, can we hold it in balloon? I know, that the atom is hydrogen is reactive. But when all atoms will have similar spin, reactions between them will ...
0
votes
0answers
63 views

General Relativity - General Recap

I would really appreciate a confirmation about the following statements about general relativity, which I deduced after a self-learning process (but which I am not sure of) 1) If there is no ...
2
votes
3answers
72 views

What was the energy of light thought to be before Einstein

I'm studying the photoelectric effect where it turned out that the kinetic energy of the emitted electron was dependent on the frequency of the u.v. light and not its intensity. It was previously ...
0
votes
0answers
15 views

What will be the forces acting on the solid body in the two given cases?

I was reading the following paper by my guide and I encountered the following doubts. Consider the following two situations This is the case of the static contact angle. In this case, the solid ...
-2
votes
0answers
12 views

Block on trolley [on hold]

A block is placed on the trolley. It is found after calculations that the block is at rest with respect to trolley when it is accelerating and when acceleration is zero What will be the motion of ...
2
votes
3answers
87 views

Does a photon's wavelength (and energy) change when reflecting off a mirror?

The momentum of a photon is $\ p=E/c.$ When a photon reflects off a mirror, it is elastic scattering. Elastic scattering should keep the energy of the photon. But radiation pressure states, that ...
1
vote
2answers
45 views

How do astronomers measure the mass of a planet using Doppler spectroscopy?

So, I am making an essay explaining planet-hunting techniques. And while I do get how astronomers measure the semi-major axis of a planetary orbit (using Kepler Laws), I don't get how they measure the ...
0
votes
1answer
37 views

Feynman Lectures on Physics: Vol 1, 11-6: acceleration vector

I’m trying to get through 11-6 section of Feynman’s Lectures on Physics, Vol 1, particularly explanation of acceleration vector calculation in his example: It’s clear that acceleration ...
2
votes
2answers
55 views

The driving force of entropy

In Gibbs free energy, entropy is treated as a sort of energy. The increase of entropy can generate work and release energy. However, normally energies are associated with actual forces. Light is due ...
1
vote
1answer
29 views

Quantum probability distributions via canonical traces

Given $N$ distinguishable quantum particles in the canonical ensemble, we can estimate the probability of finding one of those, labelled by $j$, in a certain position $x\in\mathbb R$ by computing \...
0
votes
0answers
24 views

Difference between electrical conductivity and optical conductivity

Is there any difference between electrical conductivity and optical conductivity? How to explain it physically and is there any method available to connect them mathematically? If I calculate carrier ...
4
votes
4answers
88 views

How exactly is white light a combination of several wavelengths?

I have read that light is an electromagnetic wave. Every ray of light has a specific wavelength. The colour perceived by any observer is dependent upon the wavelength of the incident light. What I ...
0
votes
0answers
12 views

Book recommendation for Tree level calculations for decay rates and cross sections?

I know how to do tree level calculations, I just want to copy expressions for Standard model interactions rather than doing them all myself. Is it possible to find them in a table somewhere ?
-6
votes
0answers
25 views

Applying Newton's Law of Universal Gravity [on hold]

At what distance above the surface of the earth is the acceleration due to the earth's gravity 0.980 m/s^2 if the acceleration due to gravity at the surface has magnitude of 9.80 m/s^2? Radius of the ...
0
votes
1answer
21 views

Does the equation of state include all the possible states that a system can exhibit?

For a given amount of a chemically defined homogeneous fluid, the equation of state is often represented as $$f(p, V, T) = 0.$$ But, does this include all the possible states that the fluid can be in?...
0
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0answers
14 views

“Euclid’s test” , Negative Pressure and Measure Theory

I don't understand what does it mean for 'Euclid's Test' when they talk about negative pressure Using Euclid’s test for a hypothesis of examining its implications, one finds that negative pressure ...
1
vote
0answers
29 views

How many different ways can Riemann-Christoffel Curvature Tensor can be derived?

In today's Relativity and Gravitation class, my prof was discussing about Riemann-Christoffel Tensor and he derived it. But in the end he told that there are many ways one can derive the Riemann ...
-1
votes
0answers
15 views

force by an air particle when hitting another air particle

I just had this really weird question. On average, how much energy is lost, when one air molecules hits another air molecule? By air molecule I mean one molecule of the gases in the atmosphere. On ...
0
votes
0answers
18 views

Deriving hadrons by their quantum numbers

While preparing for an exam I found a problem where one has to find the composition of hadrons given their quantum numbers. $$\text{ (Charge, Baryon number, Strangeness, Charm, Bottomness)=(Q,B,s,c,b)...
0
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0answers
20 views

Temperature relation to Gibbs free energy

The equation to calculate gibbs free energy includes the absolute temperature of the system. However isn't it the energy needed to raise temperature independent of the initial temperature? Why does ...
0
votes
1answer
16 views

Acceleration of blocks around accelerating pulley in inertial frame [on hold]

I am being troubled by this question: A non stretchable thread with masses $m_1$ and $m_2$ attached to its end is thrown over a pulley block. We begin to lift the pulley block with acceleration $...
-2
votes
1answer
28 views

$n$-simple pendulums [on hold]

Can I use Lagrangian mechanics to model a $n$-simple pendulum system where $n$ stands for any natural number? If so, please tell me how.
1
vote
0answers
19 views

Can the ADM mass be defined locally inside a closed surface?

To calculate the ADM mass, one has to specify a closed surface inside which all the mass is located. Are there any ways to calculate the mass inside a closed surface outside of which other mass still ...
0
votes
2answers
79 views

What if we compress space? [on hold]

If the space/universe is expanding what will happen if we try to compress it? Is it possible?
0
votes
0answers
19 views

Open boundary conditions: is the minimal period $2 L$?

I already asked this question on the math stack exchange but even if it is a math question it is something common in physics so I think it is more relevant to ask it here. https://math.stackexchange....
0
votes
1answer
32 views

What crystals are being used in this project to detect dark matter?

I recently read an article about "groundbreaking Australian research in the hunt for dark matter", in which it said: We use highly purified crystals to detect dark matter. These crystals react when ...
1
vote
1answer
32 views

Determine canonical fields of action

I'm working on an exercise which asks me to determine the canonical fields, and their equations of motion, of this invariant action: $$ S = \int d\tau \sqrt{g_{\tau\tau}}\left( \frac{\tilde m}{2} g^{\...
0
votes
0answers
15 views

Potential and work across capacitor-battery circuit

Suppose, we have a simple capacitor/battery setup like that shown below. The battery is used to charge up the capacitor. After the capacitor is charged, there will be equilibrium, the field of the ...
0
votes
1answer
38 views

Unreachable relavistic particle in accelarated motion

Let's say I have a particle in a uniformly acclerated motion such that $$ a_\mu a^\mu = -g^2, \quad g > 0\ {\rm and\ constant} \tag1 $$ I want to prove that any signal coming from a apace-time ...
1
vote
2answers
85 views

How do you experimentally distinguish $\psi_1 \otimes \psi_2$ and $\psi_2 \otimes \psi_1$?

What I am asking is that $\psi_1 \otimes \psi_2$ and $\psi_2 \otimes \psi_1$ are obviously different states. However, theoretically a measurement can be done that these to states will give two ...
-2
votes
0answers
10 views

Finding Average Speed [on hold]

d1 = 350km at xkm/h d2 = 120km at x-15km/h suppose time taken for each part of the journey is the same. What is the average speed for the second part of the journey?
0
votes
0answers
8 views

Question about circular motion and a string [on hold]

A small particle attach to the one end of string. The other end of the string is attached to the fixed point. The mass is raised such that the string is horizontal released. The locus of the tip of ...

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