General Q&A about physics of any type and at any level
Filters (None)
A computer can store some number $n$ of bits in memory, and it can perform some number $m$ of essential computational operations, such as addition or multiplication, and rewrite those bits to memor...
We commonly say that something has a weight, which is synonymous with a mass. Things have a weight because the force of gravity is relative to something’s mass. Subatomically, what is mass? There ...
Suppose we have a gravitational wave which obeys the equation: $[G_{tt}-c^{2}G_{xx}]h_{\mu\nu}=0$ Lets take the case where $h_{\mu\nu}\ne0$ so we are left with the classical wave equation.Suppose...
Presuppose that I need vinegar of $c$ concentration, where $c$ < any concentration listed below. Let $w$ be the price of water that I'll use to dilute. How do I deduce which concentration (of V...
In the context of quantum field theory, why is it impossible for two photons (or other massless bosons like gluons) to collide and produce a single photon? This kind of a process is supposed to be ...
I'm trying to understand the uncertainty principle and its implications for particle measurement. From what I've read, it seems that the principle states that we cannot simultaneously know the exac...
Question I was wondering what force make drop slow down? Does every time a drop push toothpick back into bottle? And of course how to solve it. Struct This is a bottle be pierced by a wooden too...
Starting from the classical osmosis experiment, a U-shaped tube with a semi-permeable membrane, I would like to consider the case when the solute added to one of the compartments (labelled A) is co...
There are a couple different types of indoor air humidifiers. Most notably, the naive steam humidifier with a heating element, and then ultrasonic humidifiers. Now, heating water to create steam o...
Maxwell's first law in differential form states that $$ \triangledown \cdot E = \frac{\rho}{\epsilon_{o}} $$ . In case of 1d can we say that $$\rho = \lambda$$ where $$\lambda$$ is the linear char...
Gravitational waves can be derived from the non-linear Einstein field equations and since they are by definition waves they must obey the wave equation: $u_{tt}=c^{2}u_{xx}$ but in General Rela...
Lets say we have a mass connected to a spring.Assuming not any friction the ODE which describes the system is $m\frac{d^{2}x}{dt^{2}} = -kx$ We can set 2 Dirichlet boundary conditions $x(0)=0$ an...
Suppose we have a arc of charges with some charge density $\lambda(\theta) = sin\theta$.I am using polar coordinates for convenience.But how can I find the direction of the unit vector of the net e...
Suppose we have a free falling object inside a planet's gravitational field with strength g.The planet's atmosphere provides a drag force which is dependant from the u^2 of the particle. Suppose t...
My optometrist said that round eyeglass lenses are OPTICALLY better than rectangular, particularly to correct myopia. He was NOT referring to fashion or style. I couldn't understand his explanatio...
The title is a framing for a theoretical question; I'm not asking for practical advice. A friend was recently in this situation and my attempts to apply what I remember of a couple semesters of co...
If we have a LC high pass filter the transfer function H(s) becomes: $$ H(s) = \cfrac{sL}{sL + \cfrac{1}{sC}} $$ If we solve for s to find a pole of the transfer function we get: $$ s = j \cfrac...
When a pendulum made of a conducting material moves through a magnetic field, it's a well-established fact that it experiences a retarding force, thus slowing it down, however, I'm unable to unders...
Suppose we perform the double slit experiment , but we fire instead 2 electrons instead of 1. In the double slit experiment performed in the 1920s a interference pattern was observed at the screen...
I was looking for book on classical thermodynamics. I found lot of related posts in PSE but couldn't find a book which type I was expecting. I was searching for book which covers the whole thermody...
I need to separate these two parts, the opposite of the GIF below. While my hunky husband was lifting the chair up, and my brawny brother pushing the frame down, I kept hitting the top of the slid...
With time dilation a cosmonaut could travel forth in time, especially in light speed. But are there much lesser speeds which might be achievable by humans in the next 100 years which could also in...
At home daily, I need to mix my table salt + COLD tap water. As "Marine salts dissolve faster and more thoroughly when added to circulating water," I "use a powerhead to speed up mixing time — my V...
Part 1 Say we have a round water pool, the radius is 10m, and the water depth is 2m. C is a fixed point: Fixed on the surface of water. Fixed at the center of the pool. F1 is stable forc...
In the lab I changed the angle the light hits a photoresistor and it doesnt obey Lambert's cosine law the conductivity of the photoresistor drops fast from +-20 to +-30 degrees angle.Why?
Momentum is proportional to an object's velocity, and kinetic energy is proportional to the square of its velocity $\dfrac{mv^2}{2}$. It's pretty intuitive that if object B is going twice as fast a...
I never grokked the optics behind LightHouses and the WW2 poster below work. LightHouse beams are narrow and focussed. Doubtless, the light source can fail to illumine a seafarer or the enemy subm...
I was reading about Ether, Maxwell and Young-double-slit experiment. I got a question about Ether law. Let me say what I read about Ether Law. Suppose, a boat is traveling with Adverse of Water ...
Get 2 conductors and seperate them we can use Gauss's law to calculate the capacitance created by the seperation of the 2 conductors.Can we use other laws of electromagnetism to calculate the induc...
Suppose we are using a force gauge to measure gravity in a planet. We set the gauge force to the 1N range which has a resolution of .01 N. From its specs the error introduced during the measurmen...
$$\begin{alignat}{2} && \vec \nabla \cdot \vec D & = \rho_f \\ & \implies &\int_V \vec{\nabla} \cdot \vec D \mathrm d\tau & = \int_V \rho_f\ \mathrm d \tau \\ & \impl...
The general formula for a EM wave (solving for the E field) is: where $\varepsilon = \varepsilon _{r}+j\frac{\sigma }{\omega }$ My professor told me that the conductivity of vacuum is 0 so we...
What are the SI units of the wavefunction Ψ(x).I know that [Ψ(x)]^2 describes the probabilty of finding a quantum object at a certain quantum state but what about the wavefunction instead?
If I have a rocket with some known number of engines $n$, each producing thrust with arbitrary direction $T_n$ and center of thrust $r_n$, the total thrust amount and direction $T_{total}$ is equal...
How to derive the Lagrangian differential force? $$\frac{d}{dt}(\frac{\partial L}{\partial \dot{x}})+\frac{\partial L}{\partial x}=0$$ I was trying to do something. $$L=T-U=\frac{1}{2} m\dot{x}^...
Suppose a ferromagnetic material with initial magnetization $M_o$.Is there some specific formula which calculates the total magnetization $M$ as a function of $M_{o}$ and the Curie temperature $T_{...
Im designing a capacitor and I have decided to make the surface of 1 plate of the capacitor bigger than the other plate. How are the charges sorted through A2?Are they spread out to cover all th...
If we have a force which changes depending on the position of a particle, how can we find the position of the particle at some time $t$? We can find its velocity if it has travelled a given distan...
These WorldFamous companies advertise that their lenses can control myopia for kids, NOT adults. But none of these lenses are approved by FDA. I asked my optometrist why merely kids, not adults. Bu...
What examples of a system can be described by a system of ordinary differential equations?
Which one is correct? $$E=mc^2$$ or $$E^2=(mc^2)^2+(pc)^2$$ I mostly seen $$E=mc^2$$ from my childhood, and when I was learning problem solving in relativistic mechanics I had seen $$E^2=(mc^2)^2...
We have place a charged particle of 2C with mass 2kg, 1mm above a current-carrying wire of 1A.The charged particle has an initial velocity of 100m/s The magnetic field of the wire for simplicity w...
Say we have a four underwater components tidal power / hydro power system. Component A. A propeller would always orient along the same direction regardless the direction of the flow. This is th...
In classical physics book of kleppner, i read that An atom can "jump" from one stationary state a to a lower b by emitting radiation with $E_a-E_b$. The frequency of the emitted "package of radi...
I have heard the physicist Laurence Krauss claiming that he believes that the universe is flat. Okay, but if we take four astronomers and we put one in the north pole, one in the south pole, one i...
I know that equation for parallel resistance is $$\frac{1}{r_{tot}}=\sum_i \frac{1}{r_i}$$ But i wonder to see equation of series spring constant. If we add multiple spring in series. Then their ...
Suppose we have an electric dipole of charge Q+ and Q-.The charges of the dipole are fixed (they cant move closer to each other than they already are).If we place a test particle at some distance r...
In my notes from University the reason a material can exhibit superconducting properties is at really low temperatures electrons form Cooper pairs of which the electrons of the Cooper pairs have lo...
I was looking for equation of motion. I came up with a solution but it doesn't satisfy me. Cause I was trying to find motion of that particle using Lagrangian. We know that $$W=\int \vec F\cdot d\...
Since, there's no book category currently so, I am asking it here. And, It can be moved to that category later. I want to start learning now so, I don't want to wait. Which book is best for Clas...