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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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### 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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### 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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### 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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### 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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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} = ... 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 ... 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 ... 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 ... 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 ... 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. 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 ... 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. ... 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 ... 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 ... 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 ... 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 ... 1answer 28 views ### What is the difference between vapor and gas? Please try to answer it simply. Dont copy from google please! 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 ... 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}\... 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}$$But I didn't quite get why mgh is divided by 2. When I looked ... 0answers 9 views ### Mass and flavour eigenstates in SM From what I understand, if we develop the terms in the Lagrangian of SM containing the SU(2) quark doublets$$Q_{i,L}=\begin{pmatrix} u_{i,L}\\ d_{i,L} \end{pmatrix}$$with u_i=u,c,t and d_i=d,s,... 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 ... 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 ... 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}\... 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 ... 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 ... 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 ??? 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 ... 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}}... 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 ... 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." 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 ... 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 ... 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? 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^{+})$$where g_2(D^+) is the contact value from the right-side of the radial distribution ... 1answer 29 views ### Does the energy density of space create cause gravitational attraction beyond what would be computed from an object's mass alone? I am starting from the assumption that the gravitational warping of spacetime increases its volume, so a spherical region of space with a fixed surface area would be able to fit a larger number of ... 0answers 35 views ### Pertubation Theory For long-range barrier tunneling, consider three qubits governed by the Hamiltonian H.$$ 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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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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### 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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### 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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### 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 ...