All Questions

My question is rather simple. Why do we say that is the static friction or to be more precise, the component of static friction which provides the centripetal force? The car is in motion. And static ...

If I'm not mistaken, there are analogies between the translational dynamics of a rigid body and the rotational dynamics of that body. For example, the position of a rigid body is analogous to the ...

I'm pretty comfortable with QFT, but this is a conceptual point I feel shaky on. For example, when creating Z bosons in a process like $e^+ e^- \rightarrow Z Z \rightarrow f^+ f^- f^+ f^-$, the Z ...

I'm trying to solve a problem and I have some problems for that. The problem is to show that $\eta^{\mu\nu}T_{\mu\nu}=0$, where $\eta^{\mu\nu}$ is the Minkoswki metric: diag(1,-1,-1,-1), and $T_{\mu\...

Theories surrounding wormhole based time travel are annoying me tonight... So the way time works is relative, right? The closer you are to the frame of reference, the faster time moves. So, if we use ...

suppose that I send my twin away from the earth at 87% the speed of light. From the time dilation equation, since the twin is moving, the time interval between any 2 events, as measured by me, would ...

In below diagram, in what angle $\theta$ should we drop $m_1$ so that, right at the moment of dropping, $m_2$ would lift upwards? Assume $m_2=2m_1$. This is in my homework and I don't even understand ...

I have to derive the path of a light ray traveling in a stratified medium with linear variation of its refractive index. For context the first two exercises ask you to derive Snell's law using ...

This new video from the slow-mo guys captures the explosion of an apple when it is rotated really fast (roughly $109$ rotations per second). But can someone explain me why did it cut into clear halves ...

Lesser the distance higher the force of attraction.but why it is the square of distance?And also the reason i guess for this force is the attraction force between atoms ( electrons of one atom and ...

A thermal cycler is a chemistry lab device that increases or decreases the temperature of the material inside it. The lid of the device is heated to prevent condensation and evaporation of the mixture ...

What should be the correct definition for a flow between infinite parallel plates? If I have a very long rectangular channel with height H and width W, can I approximate the flow through the channel ...

I was thinking that the reason behind the gravitational force is the magma, but after studying Newtonian model of gravity I am confused. It says that there can be gravitational force of attraction ...

To help me with a project I'm working on, I attempted to solve what I thought was an easy problem. There is an infinite, conducting cylinder of radius $R$ at some potential $V$, located a distance $b$ ...

In Michelson's Interferometer (1881 experiment), even though the arm length for both the perpendicular arms was taken as the same (say $L$) and a compensatory plate was used to removed optical path ...

I have seen a lot of posts asking about the difference between the rapidity $y$ and the pseudorapidity $\eta$, and I understand it well enough (at least in the context of heavy-ion collisions). They'...

I see at least two different definitions of Berry curvature in literature. One is given at Wikipedia $$ \Omega_n = i\sum_{n\ne n'}\frac{ \langle n|\partial_{k_x} H|n'\rangle \langle n'|\partial_{k_y} ...

To find the attractions between planets and stuff like that, you use the center of gravity/mass to apply to Newton's equation. So even if those planets collided into each other, you could separate ...

I'm assuming the angle of incidence to be the number of degrees from a perpendicular line on the side of a prism the ray starts passing through... I'm trying to figure out the angle the ray would be ...

In a physics class, I learned about Van Der Waals forces that allow geckos to stick. Do they have any relation to the Van Der Waals Equation relating gas pressure to temperature and volume?

Please anyone would it be possible to explain the process with detail of example 2 in the website I will link which measures Newton’s law of cooling with an uncertainty in temperature. Please I really ...

Note: I'm a bit new to this subject, so I'm looking for some general answers, ballparks, and direction to continue my research. Scenario: I have three electromagnets capable of X amount of holding ...

why lines of Lyman series are absent in absorption spectrum of hydrogen ?

I am trying to build a simple understanding of what a spinor is, in doing so I have stumbled across two different definitions of spinor: First definition: If $|\psi\rangle$ is a generic state of a ...

Electrons in conduction band of metal is delocalized. (1) How much is it delocalized? Will it be delocalized to the whole metal sample, or will it's wave function only cover a few/a dozen atoms nearby?...

I have trouble filling in the essential step of solving the $CP^N$ model in large $N$ limit, described on Page 84 to 86 of Michael Dine's Supersymmetry and String Theory. The Lagrangian is given by $$...

In Laughlin's gauge argument for integer quantum Hall effect, we adiabatically thread flux from $0$ to $\Phi_0$ (the flux quantum) into the Corbino ring Hall bar, and the system is left invariant and ...

While learning about shock waves in an introductory Gas Dynamics course, it was revealed that normal shocks are unstable if formed in a converging channel. Even if the local conditions ostensibly ...

On a metal ball with perfectly smooth surface with negative charge on it, the charge will be distributed evenly on the surface, but microscopically where exactly will the charge reside? Although the ...

I have been thinking about a certain step in hafting an axe which I can't seem to explain physically. As a reference, I've found a forestry manual which explains the process, in case my explanation is ...

I want to understand the physics that occur during the attempt at tipping over a bottle / rocking a bottle back and forth. I am expecting that: when the finger pushes the bottle for a tiny moment, it ...

Consider a travelling wave $\Psi(x,t) = A e^{i(kx-\frac{\hbar k^2}{2 m})}$ According to the formula for probability current $J = \frac{\hbar}{m} Im( \Psi^*\frac{\partial\Psi}{\partial x})$, the ...

This question is strongly related to this other question regarding the definition of spinor. Let's take for example the following exercise: Given a particle with mass $m$ and spin $1/2$, described by ...

When plane EM wave go thourgh ordinary dielectric, the small separation of atomic nuclei and the electron (i.e. dielectric polarization) will result in the dielectric constant and the slow down of the ...

I have a trouble with a simple question (I think). Well, if a have a tank full of compressible air at a pressure of for example 6 bar and a valve with a hole of 8 mm diameter, how can I know the ...

The phenomenon is: A semi-opaque semi-rigid plastic sheet covers a window, if you see the sheet directly from any direction, there is no iridescence on the sheet. But if you see the sheet through a ...

How does Lagrangian mechanics apply to the elastic collision of particles?

I saw this answer here but didn't understand it. If someone could provide a simpler proof starting from newton's second law F = ma and only using his 3 laws that would be helpful (only because I don't ...

When Zee computes the Grassmann path integral in Section II.5 of his QFT book, he uses an algebraic step I can't follow. I follow this part: \begin{align} \text{Tr}\ln\!\big[\gamma^5\big(-i\gamma^\mu\...

I was reading a pdf online and it's author said Consider the bcc lattice with single atoms at each lattice point, its unit cell can be reduced to two identical atoms. Atom 1 is at 000 and atom 2 is ...

In the grand canonical ensemble, the equilibrium density operator is given by $$\hat{\rho}_{\rm eq}=\frac{1}{Z}e^{-\beta\left(\hat{H}-\mu\hat{N}\right)}, ~{\rm with}~ Z={\rm tr}\left[e^{-\beta\left(\...

This is building off of a question I asked here. When discussing the linked problem with some friends, the consensus seemed to be that the reason two identical semi-infinite plane waves cannot ...

According to Wikipedia, the ergodic hypothesis is the assumption that all accessible microstates are equiprobable over a long period of time. My question is about the precise meaning of "...

I was wondering how we define IR-fixed point, when we have more then one coupling. When the coupling is unique, it is simple, because we can look at the beta function of the coupling and determine ...

Since the final Black Hole (BH) had 3 solar masses less of mass than the original binary BH, it seems the 2 BHs lost mass, and with it event surface area, entropy, and information. If that came from ...

I would like to write Schrödinger equation in polar coordinates in momentum representation (because I have a potential depending only on distance) . Would momentum operator be still just a ...

In a floating gate transistor, the gate is electrically isolated. I have a few questions regarding the quantum nature of this device: It is sometimes mentioned that, to store or deduct charges from ...

In a Mach-Zehnder Interferometer, which of the following represents the output state: $BS2~ M1~ BS1~ (input~ state)~ BS1^\dagger~ M1^\dagger~ BS2^\dagger$ $BS2~ M2~ BS1~ (input~ state)~ BS1^\dagger~ ...

I am having trouble deriving the Lorentz Force,$\vec{F}=q(\vec{v}\times\vec{B})$, from Faraday's Law, $V=-Nd/dt[Psi]$. $v$ is velocity while the $V$ is voltage.

I have a (probably simple) question about the completeness relation in dirac notation. Mostly I just want to check if I am understanding this correctly, because I can't actually find this mentioned ...