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Finding the number of revolutions that a solid sphere takes given tangential force, radius, and angular speed

I am tackling the following problem: A 29.6 kg solid sphere of radius 2 m is being rotated by applying a constant tangential force of 498.9 N at a perpendicular distance of 2 m from the rotation axis ...
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0answers
7 views

How can change in direction of force on pulley affect this situation

This problem (the b part) asks me to find the acceleration of the blocks but I'm quite not able to understand 2 thing 1.how the change in direction of F will cause the change of acceleration. How to ...
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1answer
9 views

Zeptosecond smallest unit of time? How?

There is this newly discovered zeptosecond discovered by scientists. I have seen some articles calling it smallest unit of time ever measured. How can it be possible if Yoctosecond already exists ...
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2answers
13 views

Definition of refractive index

My TB says absolute refractive index of a medium $n = \dfrac{c}{v}$ where $c$ is the speed of light in vacuum and $v$ is the speed of light in the medium. Why hasn't it been chosen the other way round ...
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0answers
7 views

Amplitude of quark$+$antiquark $\rightarrow$ ghost$+$antighost in QCD

Since the BRST charge operator commutes with the Hamiltonian of QCD, a physical state such as $q+\bar q$ should not be allowed to evolve into an unphysical one like $\chi+\bar\chi$, where these two ...
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5 views

Can we differentiate flows with identical Reynolds numbers but with different turbulence intensities?

The Reynolds number is given by $$\mathrm{Re} = \frac{v_{rms} L}{\nu}$$ Now imagine we fix $L$, $\nu$ and $v_{rms}$ - so the Reynolds number is constant. Imagine two different flows: $$(1): \bar{v} = ...
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0answers
7 views

HOW S1 can move to another planet and S2 move in elliptical orbit around earth,if initially both are in circular orbit? [closed]

Two artificial satellites S1 and S2 revolve around the earth in circular orbit of radius twice earths radius. At certain moment,satellites separate from one another.S1 moves to another planet and S2 ...
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4answers
34 views

What do gases do work on in a thermodynamic system?

According to Wikipedia In physics, work is the energy transferred to or from an object via the application of force along a displacement. But for a gas in a closed vessel with movable massless ...
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1answer
29 views

Violation of time reversal symmetry

Can anyone please provide me with an example of unperturbed Hamiltonian for a certain physical system, which has no time-reversal symmetry, the only condition is that the spectrum of unperturbed ...
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0answers
16 views

How to calculate separation when velocities are at some angle?

original problem Two ships A And B originally at a distance $d$ from each other depart at the same time from a straight coastline. Ship Moves along a straight line perpendicular to the shore while ...
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1answer
16 views

Wave explanation and derivation

Why must the term $kx-\omega t$ be constant? I mean from an intuitive point of view. I can mathematically prove it, however I don't seem to understand it very well.
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0answers
13 views

Polarization by Scattering

Above this sentence is an image of the diagram and paragraph I have been reading about polarization via scattering. Question: Light EM waves are transverse waves aka move perpendicular to the ...
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1answer
32 views

Is the aceleración the quotient of the inner product (of velocity and acceleration) and the speed? Proof

The inner product of acceleration and speed is (the product of) both their moduli times the cosine of the angle between them,which divided by speed leaves the acceleration (modulus) times the cosine. ...
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1answer
31 views

When exactly does the velocity of a cart change?

I have done many problems where where a small body is thrown from a moving cart and we have to use conservation of momentum to find the final velocities of the cart and the thrown object. To find the ...
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0answers
7 views

Relation between the spin of a field and the way charges interact

When solving the problems of V. Rubakov's "Classical Theory of Gauge fields" book, I encountered the following phenomenon: For a real scalar fields (spin 0) $\phi$, if we consider the ...
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1answer
27 views

Is the ear really phase insensitive?

If the ear is phase insensitive (Ohm’s Law of acoustics), and you listen on headphones, how can the brain hear a phase inversion on one channel of a stereo signal? I play bass guitar and practice on ...
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2answers
41 views

How to make conclusions about a body moving in an accelerated frame as an observer in an inertial frame of reference?

Consider the question from this post where I had asked about a scenario where a pendulum was attached to the roof of a car and I wished to understand how people in different frames would understand ...
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1answer
28 views

What is the difference between vapor and gas?

Please try to answer it simply. Dont copy from google please!
4
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1answer
28 views

Why can't a flame from a lighter touch water from a running faucet

I was conducting an experiment to see if my sink faucet is flammable. I did this by putting a lighter near a running facet. My first guess was that the flame will go out because of the water. But I ...
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1answer
21 views

How does a general electromagnetic wave equation looks like?

I know that electromagnetic wave consists of electric field and magnetic field, say: $ \overrightarrow{E}\left(x,t\right)=E_{0}\cos\left(kx-\omega t\right) $ $ \overrightarrow{B}\left(z,t\right)=B_{o}\...
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2answers
20 views

Work done on objects like chains

Consider a chain of mass $m$ whose one end is lifted upwards to a height $h$. The work done in this case would be $$\frac{mgh}{2}$$ But I didn't quite get why $mgh$ is divided by $2$. When I looked ...
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0answers
9 views

Mass and flavour eigenstates in SM

From what I understand, if we develop the terms in the Lagrangian of SM containing the $SU(2)$ quark doublets $$Q_{i,L}=\begin{pmatrix} u_{i,L}\\ d_{i,L} \end{pmatrix}$$ with $u_i=u,c,t$ and $d_i=d,s,...
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0answers
5 views

Determine initial permeability from experimental data

How to determine initial permeability of the sample having only its dimensions (ring with $R$ - external radius, $r$ - internal radius, and thickness $h$), the number of coils around it $N$, and only ...
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0answers
15 views

A uniform rope of mass 2 kg which can tolrate maximum tension 80 N at any point, find the maximum value of F which can be applied on 2 kg block [closed]

https://toppr-doubts-media.s3.amazonaws.com/images/3393752/215e7193-643e-44b4-829f-885c505f7598.jpg A uniform rope of mass 2 kg which can tolerate maximum tension 80 N at any point, find the maximum ...
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1answer
20 views

Confusion on wave packet and creation operator in Mark Srednicki's book

In Mark Srednicki's QFT book, section $5$, he mentions following things: $a^{\dagger}(k)$ creats a particle with momentum $k$ and is given by \begin{equation} a^{\dagger}(k)=-i\int d^3x [e^{ikx}\...
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2answers
29 views

A basic question on center of mass

Being a high schooler , I read the concept of center of mass and it was written that When a spinning ball is projected with some velocity , then all the points on the ball have complicated paths ...
0
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1answer
26 views

Confused in Newton's second law for rotation

I am a high school student and I am very confused about a thing which is from rotational mechanics my confusion is that we are often taught that $\tau=dL/dt$ and $\tau=I\alpha$ are the same if the ...
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0answers
14 views

Is it possible to find the moment of inertia at a particular point in a body with uniform mass distribution

Can i find the moment of inertia at P if the axis is XX'(passes through the COM) or is the moment of inertia same at every point ???
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1answer
9 views

Experiment carried out to measure the Huygenian wave behind an opening all over 180°

I‘m curios about the verification of the Huygens-Fresnel principle for light. For water it is clear visible in experiments, that the wave behind an opening disperses out all over 180°. For light the ...
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0answers
12 views

Scattering problem with spin

My question is how to enter spin in the scattering problem? The simplest example is: consider two spin-$\frac12$ particles and the following potential: $ V(r) = \sigma_1.\sigma_2 \frac{e^{-\lambda r}}...
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0answers
4 views

Magnetic Lens Size required to ignite a Fusion burn

What are the dimensions and/or mass of the amount of permanent magnets( NdFeB) required to magnetically focus cosmic rays such that instead of 1 muon per square centimeter per minute hitting the ...
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0answers
5 views

Can someone explain me the following line: “The RC circuit averages past history at the input with a weighting factor of e−Δt/RC.”

"The RC circuit averages past history at the input with a weighting factor of e−Δt/RC."
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2answers
22 views

How to calculate the amplitude of a matter wave of debroglie equation?

I studied the formula that to calculate the wavelength of a matter wave we have to calculate $h/p$ where $h$ is plancks constant and $p$ is the momentum of the particle for which we want to calculate ...
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1answer
17 views

Optics Total Internal Reflection Critical Angle

When a ray of light coming from the medium $n_1$ $\mbox{ has an incident angle } \theta_1 = \theta_c$ where $\theta_c = \mbox{critical angle}$ what phenomenon are we observing? Is it called a partial ...
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0answers
20 views

Velocity between two opposing charges

My question is Q: when two charges $+ Q $ and $-Q$ symmetrically approach each other to $L$ length then what would be their individual and combined velocities?
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0answers
7 views

Deriving relations for a hard sphere phase diagram

In Torquato's Random Heterogeneous Materials, he has written $$\frac{p}{\rho kT} = 1+2^{d-1}\eta g_2 (D^{+})$$ where $g_2(D^+)$ is the contact value from the right-side of the radial distribution ...
0
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1answer
29 views

Does the energy density of space create cause gravitational attraction beyond what would be computed from an object's mass alone?

I am starting from the assumption that the gravitational warping of spacetime increases its volume, so a spherical region of space with a fixed surface area would be able to fit a larger number of ...
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0answers
35 views

Pertubation Theory

For long-range barrier tunneling, consider three qubits governed by the Hamiltonian $H$. $$ H = -J(\sigma_1^+\sigma_2^-+\sigma_1^-\sigma_2^++\sigma_3^+\sigma_2^-+\sigma_3^-\sigma_2^+)+\frac{U}2\sigma^...
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2answers
31 views

Changing up Newton's cradle

My professor explained Newton's cradle and then gave us the question: if you taped together the last 3 balls and pulled up and let go the first one, nothing would move on the other end but momentum is ...
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0answers
16 views

Problem about the molar heat capacity of a metal

I am trying to resolve this issue and would greatly appreciate your help: The molar heat capacity of a metal at low temperatures varies with temperature according to the equation: $\cfrac{C}{n}=\left(\...
0
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0answers
9 views

How to show that a system of even number of Fermion has integer spin?

I am informed that a system of even number of fermions has integer spin. I don't know how to show it with creation and annihilation operators.
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0answers
21 views

Number of independent components of Lorentz transformation matrix $\Lambda^\mu_{\,\,\,\nu}$

I asked a question before here. I am trying to follow Weinberg's derivation (in the book Gravitation and Cosmology) of the Lorentz transformation or boost along arbitrary direction. I am having ...
1
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2answers
30 views

COM frame for photons

We know that there is no frame in which the energy of a photon is zero and hence it has zero momentum. But can we find a frame in which the energy of two head on photons is zero, or the center of mass ...
2
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1answer
58 views

Temperature of a gas: Is it velocity only?

I've been going through Feynman's lectures. One thing he said, unless I misunderstood, is that the temperature of a gas molecule is determined by its velocity, but not its vibration or rotation. Did I ...
0
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0answers
15 views

Vertical air speed

Assuming that the divergence varies linearly with the pressure between the surface ($1000$ hPa) and the tropopause ($200 $ hPa). Can someone tell me how do we calculate the vertical speed on the ...
-1
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0answers
20 views

Superfluid Dark Matter Vortices

I am curious about the community's opinions on the concept of the copious amounts of dark matter actually being comprised of axions that behave like a superfluid (bosonic) at the cosmological scale, ...
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0answers
12 views

How much of a “magnetic B field” can be expelled or shielded by a spherical superconductor or mu-metal sphere?

In a standard average 4 inch square magnet, What is the value of the Magnetic B field vector at a specified moment in time for such a magnet? Of that number, what is the direction of this particular “...
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2answers
51 views

What does the sign of potential energy mean?

For a system of two particles, we often let the potential energy for the force between the particles approach zero as the separation of the particles approaches infinity. If this choice is made, why ...
0
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0answers
20 views

How can I figure out how many terms to keep in a series solution to recover the analytical solution within a given % (e.g. 1%)?

For one of my homework problems we were tasked with finding the analytical solution as well as the Fourier series solution for a potential. I have found my two equations that do this. Analytical ...
-1
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2answers
88 views

Would everyone die? [duplicate]

When you open the door of your spaceship, the oxygen disappears from the ship. So if I put a very very long tube from the Earth to space, would all the oxygen from the Earth automatically aspire into ...

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