instruction stringlengths 31 24.3k |
|---|
Electromagnetic launchers (coilguns or railguns) use extremely high amperages and voltages, but I was wondering if are there very high voltage very low amperage electromagnetic/electrostatic launchers.
The only thing I could find was electrostatic linear motors, but they are very simple science demonstrators and nothin... |
In my Professor's notes on Special Relativity, the determinant of a rank-two tensor $[T]$ (a $4\times 4$ matrix, basically) is given using the Levi Civita Symbol as: $$T=-\epsilon_{\mu\nu\rho\lambda}T^{\mu0}T^{\nu1}T^{\rho2}T^{\lambda3}.$$ But, while trying to derive this, I seem to be missing the minus sign. My attemp... |
In Tong's lecture notes (http://www.damtp.cam.ac.uk/user/tong/qft.html) page 38, he calculates the following propagator:
$$D(x-y) = \int \frac{d^3 p}{(2\pi)^3} \frac{1}{2E_\vec{p}} e^{-ip \cdot (x-y)}.\tag{2.90}$$
Then, he states that for spacelike separations,i.e. $(x-y)^2 < 0$, one can show that $$D(x-y) \sim e^{-m|\... |
$E_0 = \frac{D}{\varepsilon_0}$, $E' = -\frac{P}{\varepsilon_0}$
$B_0 = \mu_0 \cdot H$, $B' = \mu_0 \cdot M$
（$E_0$ refers to the electric field generated by free charges, or the external electric field, while $B_0$ denotes the external magnetic field; $E'$ refers to the electric field generated by polarized charges,... |
Suppose, there a gas in a cylinder which itself is placed on a fast moving car, will there be any change in its internal energy due to the motion of the car? Do you think it may gain some kinetic energy due to increased motion of gas molecules as well?
|
The title is a bit ambiguous. More specifically, I'm asking:
Are all coupling between massive gauge fields (associated with broken generators) and massless gauge fields of the unbroken group are in the form of covariant derivatives of the massive gauge fields. (This covariant derivative is composed of massless gauge fi... |
Particle A moves at a constant velocity of = 3m/s along a straight line of = 30m. Particle A moves at a constant velocity of = 3m/s
At the moment passing through, particle B starts at rest from the origin and moves at a constant acceleration of = 0.4 m/s2 in the direction of the axis and . Find each for A and B t... |
I was watching a video and he was trying to derive a result in electrostatic pressure. He was deriving the pressure on a differential area element of a hollow conducting sphere. He did it two ways, the second way was straightforward he did it by using only gauss's law and a neat argument but the first derivation I have... |
For the scalar field $\phi$,
$$ L = \frac{1}{2}\left(\partial_\mu \phi \partial^\mu \phi + m^2 \phi^2\right) $$
The energy momentum tensor calculated using noether's theorem is given by
$$ T^{\mu \nu} = \partial^\mu \phi \partial^\nu \phi - \eta^{\mu \nu}L $$
Im trying to calculate the same thing by varying the action ... |
For example, if I have a 1/4 piece of pizza, what is the position?
|
For pure Einstein gravity with Dirichilet boundary conditions, Gibbons-Hawking-York boundary action is needed to make the variational principle well defined. I am considering the case for topological massive gravity (TMG) in 3d where there is an additional Chern-Simons action and want to know what is the additional bou... |
If a shockwave from something like an explosion travels into the ground, why will it refract? The speed of sound is far different in the ground, but what would make it refract? I can’t seem to find anything on this.
|
Yang-Mills quantum field theory predicts the existence of the lightest massive Bosonic (i.e. integer spin) particle.
This massive Boson will be much lighter than the $W$ and $Z$ Boson and therefore define the mass gap of the re-normalized zero value vacuum energy to the lightest force particle there is.
From what we kn... |
help me please
and thank you very much
|
Is there any finite charge distribution the potential of which doesn't decay with $\frac{1}{r}$ at infinity? Intuitively, if you "zoom out" any finite charge distribution, it could be visualized as a point charge with the equivalent total charge of that distribution, meaning, its potential would decay proportional to $... |
The Copenhagen interpretation of QM ultimately amounts to asserting that non-local correlations occur without a cause since that cause would involve propagation of information faster than the speed of light.
I have two questions in regards to this.
A) Why can’t we simply be wrong in thinking that information can’t be ... |
It is not clear to me how this derivation proceeds through the steps. Could someone help me understand how to arrive at this result or point me towards a resource that explains these algebraic manipulations within the Dirac Delta function?
Thanks in advance
Edit:
Apologies, not sure how I forgot to mention that P is t... |
I am currently studying scattering theory from the Sakurai's quantum mechanics. I have previously studied this subject from Griffith's quantum mechanics. In the latter textbook, scattering matrices for one-dimensional problems were discussed by solving the Schrodinger equation and taking ratio of amplitudes to determin... |
I'm currently studying antennas. The notes I'm following, while discussing the EM fields at the antenna feed port, make the following statement:
It can be shown that a propagating mode in a transmission line or a waveguide can be represented by real-valued phasor vectors e and h, known as modal vectors
Following this... |
Let us consider the equation:
$p+p\to p+p+\pi^o$
In the Center Of Mass reference Frame,
The total momentum of the system is zero.Both before and after the collision.In the lab frame one of the proton is at rest and the other one is moving with velocity $v_{lab}$ .So,in the CM reference frame both of them moves with vel... |
I've heard that momentum is always transferred macroscopically while kinetic energy of an object can be transferred microscopically, as far as I know
Why? And how does it make sense, how do we know that makes sense
If an object for example slows down to friction, the momentum goes to the entire Earth while the kinetic ... |
i want to calculate the force between 2 identical plates of a capacitor. the dielectrica in between the plates is composed of 2 layers, parallel to the plates. the upper layer is a liquid, while the lower layer is a solid. the lower dielectric is mechanically connected to the lower plate.
here my attempt of calculation... |
Consider the Lagrangian density of a complex scalar quantum field:
$$
\mathcal{L} = (\partial_\mu\varphi^\dagger)(\partial^\mu\varphi) - m^2\varphi^\dagger\varphi
$$
With the conjugate momenta $\pi^\mu = \frac{\partial\mathcal{L}}{\partial(\partial_\mu\varphi)} = \partial^\mu\varphi^\dagger$ and $(\pi^\dagger)^\mu = \p... |
I'm wondering about the physical meaning of Lorentz contraction within the scope of the special theory of relativity since there're several "real" effects that are supposed to happen due to it e.g. string braking in Bell's spaceship paradox. If we take a look at the derrivation of Lorentz contraction, we clearly see it... |
I am having trouble following the derivation in this paper https://arxiv.org/abs/1810.07775 using the method of characteristics. By using the method of characteristics, they derive the following ODEs that are satisfied along the characteristic curve:
$$
\frac{dr}{dt} = 2\gamma r - K(t)\\
\frac{dK}{dt} = w^2r(t)
$$
The... |
I really know that information have its entropy. So I guess that there's some symmetry breaking after observing vaccum. Here's my question: does observing vaccum can affect its state? Or this is nothing but quantum fluctuation?
|
I think the answer is (A) initially. However, what about option (C)? It also shows a graph with constant acceleration and a negative slope. And in option (E), the acceleration is 0. Can we consider this as constant acceleration too? It's frustrating that the question maker didn't provide the answer in their paper.
|
For simplicity I'll do this in 1 direction so I can let the sign dictate direction and ditch the vector notation.
The force done by a spring can be written as $$F = -k\Delta x , $$however this simplifies to $$F=-kx$$ if we are starting from equilibrium ($x_i = 0$) but the force required from some already stretched/c... |
What exactly is $\varphi$ referring to in this paper: Electron bunchers for industrial RF linear accelerators: theory and design guide?
Specifically, within the context of this equation:
$$\frac{dW}{dz}=qE_z \cos\varphi \ \ ?$$
|
Let me grab your attention for a moment for my physics questions.
Looking at the Alcubierre drive theory example.
There's a great example that works similar in terms of structure that works here on earth (a surfboard riding a wave).
If we were to find a similar constant like a wave, with the downward slope force in the... |
I am trying to find a means of conceptually understanding the double slit experiment intuitively. I understand that the actual reality of what happens may be different, but is there a formulation that can act as a reliable model for what happens?
For example picturing a photon as a wave of energy that expands out from ... |
I am currently studying scattering theory from Sakurai and Griffiths and I have noticed that for the 1D Dirac potential, the transmission and reflection coefficients diverge when the energy corresponds to the bound state energy. Is this only true for the Dirac potential or is it always true? If this is always true, wha... |
I'm a mathematician slowly trying to teach myself quantum field theory. To test my understanding, I'm trying to tell myself the whole story from a Lagrangian to scattering amplitudes for scalar $\phi^4$ theory in a way that feels satisfying. There's one thing that's kind of bugging me.
One of the hypotheses of the LSZ ... |
Hello i am now studying general plane motion from Hibbler dynamics , now for choosing reference point to calculate the moment about , does this point need to be in the body frame? , means to move with it , or can it be outside of the body fixed frame ? and if yes how calculations would be ? Because he said in rotation ... |
For example I have the formula:
MEI=MEF
mgh+mvi2/(2)=mgh+mvf2/(2),
What does initial and final velocity mean?
|
Suppose we have a theory that is super-renormalizable and let $\Gamma^n$ denote the sum of all 1PI diagrams of this theory with $n$ amputated external legs. In such theories, for all $n$ sufficiently large, $\Gamma^n$ is superficially convergent. For those $n$ for which $\Gamma^n$ superficially diverges, the divergence... |
What is the speed of light in a vacuum when the light reflects off of a mirror?
|
For simplicity I will be considering $\phi^4$ theory. To analyze correlation functions of the form
$$\langle \phi(x_1)\phi(x_2)\ldots\phi(x_n)$$
with
$$x_1 \neq x_2 \neq \cdots \neq x_n \tag{1}$$
we can use perturbation theory and the usual Feynman rules.
Now consider a correlation function where the condition (1) is d... |
This is taken from my physics textbook and it asks me to decompose the gravitational force on the orbiting object in an elliptical orbit into components normal and tangential and then explain why only the tangential component does work.
|
I am a high school student and has been wondering a while about this:
Why does a bulb not glow when one terminal of a bulb is connected to the negative terminal of a battery and the other is connected to the ground?
My teacher said that since we don't have a closed circuit there wouldn't be any current and thus no ligh... |
Many textbooks of classical mechanics or classical field theory mention that a three dimensional "string" (the continuum limit of a lattice) leads to/can be described by the 3 dimensional wave equation
$\square \psi =$ some inhomogeneity.
However, all of the textbooks I've read don't really show that but just say that ... |
When we differentiate the equation of trajectory, which is basically a relation between the positions of a particle across different dimensions (x,y,z), do we get a relationship between the velocities (Vx, Vy, Vz)?
For clarity's sake, let's take the example of 2D motion:
Is it possible to find out what the velocity in ... |
An interferometer acting on $N$ modes can be described in terms of an $N \times N$ unitary transformation $U$ acting on the creation or annihilation operators of the modes.
I'm wondering if there is any physical significance to the eigenmodes/eigenvectors and eigenvalues of the interferometer unitary? Are interferomete... |
If I have the energy of a free electron gas in three dimensions centered at energy $E_0$,
$$E_n(k)=E_0+\frac{\hbar^2}{2}\left(\frac{k_x^2}{m_x}+\frac{k_y^2}{m_y}+\frac{k_z^2}{m_z}\right),$$
I can prove that the density of states in the Fermi level is
$$d_n(E_F)=\frac{3}{2}\frac{n}{E_F-E_0},$$
where $n$ is the number of... |
Could someone please explain how we know the singularity has an infinite density and zero size/volume? From reading around online black holes have a defined radius (the event horizon) but this isn't its true size, it's just a reference point. If a supermassive star is so large that neuron degeneracy pressure cannot hal... |
I understand that my question is more suited in the Computational Science forum, but I want some of the issues in this question relevant to physics addressed here.
I am trying to solve the $\textbf{1-D}$ Poisson equation for a semiconductor structure at equilibrium (There is no external bias applied).
$\textbf{Backgrou... |
Work done "BY" a force,from my understanding,is:
•positive when the direction of displacement is same as the direction of force.
•negative when the direction of displacement is opposite to the direction of force.
Now,work done "AGAINST" any force, intuitively, must be equal to the resultant force,i.e.,(applied force -... |
When I was thinking of Foucault's pendulum , this question was always bugging me. If we are all rotating with the same speed in one reference frame as the surface of earth with the pendulum , then the pendulum as demonstrated by Foucault must have gone through the same place over and over again. Like a line going in th... |
I am new to electromagnetism. A few days ago, I decided to learn about electromagnetism through different books and i came across 2 different definitions about fields:
A “field” is any physical quantity which takes on different values at different points in space (Feynman Lecture on Physics, Vol II, part 1-2)
A physi... |
I am working with a He-Ne laser. What I have noticed, is that when resonator cavity length is increased (by moving on of the mirrors), output power goes down. What could be an explanation to that? Additional question: as I use different mirrors, optical power seems to go down as well. Do we have an output power depende... |
I am trying to understand how to transform vectors between cartesian coordinate systems that are rotated wrt each others. As a step in this process I have come up with a toy problem:
Consider a ground station, G.
Let us introduce a right handed coordinate system with origin in G, x-axis pointing north and y-axis pointi... |
Suppose you had a system consisting of a large propeller and engine. In this scenario, the total weight of the apparatus is $160\hspace{1mm}\text{kg}$ and the length of a single propeller blade is $80\hspace{1mm}\text{cm}$ (diameter is $160\hspace{1mm}\text{cm}$).
The force of gravity acting on the system is thus $1568... |
Consider an instance of the Ising model, with $N$ number of spins on a 2D square lattice (or any other 2D structure) wrapped into a torus to avoid boundary conditions (in other words, periodic boundary conditions) with nearest neighbor coupling.
I am sampling from the Boltzmann probability distribution: $$\mu(s)=\frac{... |
I'm self-learning some introductory plasma physics and I'm analyzing the derivation of the Saha equation for a simple first ionization plasma, with the aim of providing some insights on the involved orders of magnitude. The development I see from various sources, as far as I can understand, should go along the followin... |
From what I have read so far, I arrive to a conclusion that a stationary charge must experience a force when it is near a current carrying wire. A stationary electron should get attracted and a stationary proton should get repelled. I see there are some who agree to this, but there are many who say that a stationary ... |
My course notes say,
for normalised wave functions $\psi(x,t)$, the function $$\rho(x,t)=|\psi(x,t)|^2=\overline{\psi(x,t)}\psi(x,t)$$ gives the $\color{red}{\text{probability density}}$ for the position of the particle.
I guessed from the bold that something about this is specific to normalised wave functions, but l... |
Can someone please explain why a point originating inside the cone can never be the cause of an event outside the cone? Is there a real life example of this? The only thing I can think of is from a point inside an event horizon to outside in regular space.
|
Consider a collapsing sphere that becomes a black hole. The interior schwartzchild lightcone coordinate $U$ can be written as $U$ = $\tau - r + R_{0}$ where $R_{0}$ is the radius of the sphere before collapse. The exterior light cone coordinate is
$u$ = $t-r^{*} + R^{*}_{0}$
where $R^{*}_{0} = \int{\frac{dR_{0}}{C}}$. ... |
From the wiki page on rotation matrix:
I find this rather confusing. I understand that the resulting matrix rotates a vector roll around the fixed $x$-axis followed by pitch around the fixed y-axis and yaw around the fixed z-axis.
Since the axes are fixed this is an extrinsic rotation. And since the point is moving wh... |
I try to rephrase here a my question (https://math.stackexchange.com/q/4661784/), explaining more specifically the case.
Given a lagrangian $L=L(\theta_{\mu\nu},\phi)$ , the conserved Noether current is
\begin{equation}\tag{1}
j_{\beta}^{\alpha} \doteq - \dfrac{\partial L^{(2)}}{\partial (\partial_{\alpha}\theta_{\mu\... |
Is there an intuitive way for understanding why in lower pressure the boiling point is lower? Maybe some easy characteristic special case.
Or should I just follow equation or experiment and memorize this fact.
I am beginner in physics so advices like for kid are allowed.
|
In Special Relativity when I move backwards and forwards my hypersurface of simultaneity moves too.
Does time really oscillate backwards and forwards as I move around? Or is it just the application of coordinates? Is it just a matter of perspective. No physical change?
Some pop books I've seen say time does actually mo... |
Someone once told me that with reversible computers there is no energy cost for the computation itself, there is only a cost for running the hardware. But is this true in practice, or is it only an idealization?
|
In https://stackoverflow.com/q/75297814/
the answer for the problem was that the earth like the moon had a speed due to the moon induced orbit. I don't understand how this was calculated? I have searched all over internet but not found an explanation.
|
Suppose an affine parameter $\lambda$ is defined along a null geodesic with $dx^\mu/d\lambda=k^\mu$. How could I write the partial derivative $\partial f/\partial x^\mu$ by using $df/d\lambda$? If $k^\mu\neq0$ for all $\mu$, can I write $\partial f/\partial x^\mu=(1/k^\mu)df/d\lambda$?
|
In the kinetic theory of gases, the time taken for a change in momentum is $2l/v(x)$, where $l$ is the length of a cube and $v(x)$ is the velocity in the $x$ direction.
Shouldn't the time correspond to the momentum change of the molecule, such that the force can be calculated as $F=\Delta p/\Delta t$, where $\Delta t$ ... |
While working on a problem set I came across this question.
The figure shows a semi-cylindrical massless gate of width R pivoted at the point O holding a stationary liquid of density $\rho$. A horizontal force F is applied at its lowest position to keep it stationary. The magnitude of the force is ?
My Attempt:
Well w... |
The value of the cosmological constant is:- $+2.036\times 10^{-35} ~\mathrm{Hz}^2$. What does it mean about the characteristics of our spacetime? What does the value of the cosmological constant tell us?
Source where I got the value of cosmological constant:- https://aip.scitation.org/doi/10.1063/1.1419571#:~:text=The... |
If total power dissipated in a DC circuit is given by $P = VI$ and power dissipated as heat is given by $P=I^2R$, since these are numerically equal, wouldn’t that mean all the power is dissipated as heat? But that is of course not the case- then how do we calculate the power dissipated as electrical energy to different... |
The sun is usually assumed to be approximately very close to a blackbody, but using spectroscopy it is concluded that the sun is made up of Hydrogen and Helium because the lines corresponding to those elements can be seen in the spectrum. If the sun is a blackbody shouldn't the peak of the spectrum be determined by Pla... |
I am trying to find three integrable systems with 6 degrees of freedom using the Liouville–Arnold theorem. That means that a set of integrals of motion that correspond to a conserved quantity for every degree of freedom needs to be found. Additionally, these integrals of motion need to have vanishing Poisson brackets w... |
It is known that for most materials, permittivity is a function of frequency, and thus the value of permittivity can have a vast variation. However, in the case of air, it is often considered $\approx$ 1.
What is the physical/mathematical reason to this lack of effect on the permittivity of air by frequency?
|
I've seen across several posts, that Wick rotation is not an ordinary substitution. Instead we're rotating the contour of integral and analytically continuing time $t$ to include imaginary time $-i\tau$.
However if one looks at this post to a related question in Physics SE, one can see that Wick rotation just seems to ... |
I'm trying to prove that the electron-positron pair production cannot occur in empty space.
From the conservation of energy we have that
$$\hbar \omega = 2\gamma mc^2+E,$$
and from the conservation of momentum we have
$$\hbar k=2\gamma mv\cos{\theta} + p,$$
where $E$ and $p$ are the energy and momentum of some other pa... |
i have another question regarding calculations with the co- and contravariant formalism in QFT. It is not that i don't understand all of this, but most of the time i'm missing some "middle" steps, i.e. when reading books and trying to recap the stuff.
One example is derivation of the Klein-Gordon-Equation from the Lagr... |
When we consider such a phenomenon, what I am wondering is that the body of an object having a thin radius seems to cause the center post to be broken or the cog to be very sensitive, but why should I examine what issues?
I feel that the cog is very sensitive if I am holding a pen on my finger and the body is thin. ti... |
In the Navier-Stokes equations, there's a well-known convective term of the form:
\begin{equation}(\mathbf{v}\cdot\nabla)\mathbf{v}\end{equation}
I'm not able to understand it. As far as I know, the nabla operator is, as it name says, an operator, not simply an element of $\mathbb{R}^3$, it maps between function spaces... |
Suppose we have $N$ coupled oscillator with the fixed ends.
We can find the normal modes of this system by considering an infinite system and using space translation symmetry to diagonalize the associated matrix for equation of motion.
In infinite system, we have the solution for the normal for any oscillator as
$y_j=... |
So I know that particle accelerators use electromagnets to accelerate particles. However, since photons can be used to recoil particles (such as in Compton scattering), is it possible to use high energy photons with very short wavelengths to accelerate particles?
|
The first fission bomb was created in 1944, and the first fission reactor in 1951 (and actually productive one in 1954). This delay seems possible to explain by there being a larger amount of initial effort in building a fission bomb than a fission reactor.
But the first fusion bomb was tested in 1952, whereas we still... |
Ricci Tensor is the contraction of the Riemann Tensor. Even if all the components of the Ricci Tensor is zero, that doesn't mean that the spacetime is flat. If all the components of the Riemann Tensor is zero, then only the curvature is zero. In order for the field equations to be linear, the contraction is necessary. ... |
Essentially I've confused myself by trying to understand NMR (nuclear magnetic resonance) as the transition between hyperfine levels and I seem to encounter a contradiction. I'll describe my understanding of hyperfine structure, then my understanding of NMR, then how they contradict each other. Hopefully somebody can t... |
For various fundamental phenomena, there are visually accurate simulations. For example: electromagnetism or the Schrödinger equation.
All I can find to visualize the Higgs Field is this potential in isolation.
Are there any accurate simulations out there which show the Higgs Field interacting with a system of particle... |
In the yellow pages (Conformal Field Theory, Di Francesco, Mathieu, Sénéchal), the authors derive the conformal Ward identity in the following way:
They show that, for a conformal transformation,
$$ \partial_\mu (\epsilon_\nu T^{\mu \nu}) = \epsilon_\nu \partial_\mu T^{\mu \nu} + \dfrac12 \partial_\rho \epsilon^\rho... |
From Robert Resnick's "Introduction to Special Relativity", the frequencies in two different inertial frames as shown below,
are related by
$$f = f'\frac{1+\beta \cos\theta'}{\sqrt{1-\beta^2}}$$
which can be written inversely as
$$f' = f\frac{1-\beta \cos\theta}{\sqrt{1-\beta^2}}$$
He says that in the second equation,... |
When two charged conducting solid spheres(having charges Q1 & Q2) are connected,the charges get distributed in the ratio of their capacitance(C).C∝radius in case of spheres and hence charge distributes in ratio of their radii.
What about the surface charge densities(σ)?
I think they will distribute in the opposite rati... |
Suppose we have a simple pendulum swinging between two extreme positions. At the extreme position its speed becomes zero. As per this reason can I say that at extreme positions radial acceleration (v^2/r) is zero so tension in the string has to be equal and opposite to the mgcos☆ , where angle ☆ is angular position of ... |
recently i've started "exploring" general relativity, and found this example explaining time dilation caused by velocity:
The example was taken from https://en.wikipedia.org/wiki/Time_dilation
My question is, doesn't the example somehow assume that the glass has no mass, and therefore there is no gravity? Or even the ... |
I cannot quite wrap my head around the exact mechanism by which neutrinos affect cosmic structure growth. Their effect as dark matter is clear to me but I don't understand how their longer free streaming length sets them apart from other particles. Here is my understanding:
Neutrinos have a longer free streaming length... |
I'm currently going through Jackson chapters 3 and 4 and don't understand what exactly "$l$" or its physical meaning is when looking at the general solution to the Laplace equation in spherical coordinates, any clarification would be appreciated.
$$\sum_l (A_l r^l + B_l r^{-l-1}) P_l(\cos \theta).$$
|
I was asked to find the trace of $(A \in M_{n \times n})$, the matrix that can be written in the form:$$A=\frac{1}{n} \sum_{r, \, q \, = \, 1}^n (-1)^{r+q}|r \rangle \langle q| \quad ,$$ where {$|r \rangle$} is an orthonormal basis. I know that $(\langle r |q \rangle =\delta_{r, \, q})$ but I don't know what truly mean... |
There is one thing I can never get right. If I want to describe the strength of a gravitational field I can use the standard gravitational parameter ($\mu$), which does not take into account the distance. For example, if fly on an airplane above the clouds of Saturn I will experience a gravity very similar to what I wo... |
I recently compiled ten years of NOAA local climatological data. I noticed that the maximum relative humidity dropped linearly from 100% at about 80°F to 20% at about 110°F. Nothing obvious comes to mind that explained this observation.
Here is my scatterplot:
Here is graph showing the edge of interest:
I would have ... |
In classical mechanics the balancing lever equation (law of the lever) is
$$M_1 a = M_2 b$$
Where $M_1$ is the mass at a distance $a$ from the fulcrum and $M_2$ is the mass at a distance $b$ from the fulcrum.
Is this the same as in other physics such as special or general relativity ?
I considered lenght contraction an... |
Logarithmic scales are not uncommon: magnitudes in astronomy, f-stops in photography, the Richter magnitude scale, etc.
But decibels are weird.
I am not even talking yet about the fact that we use a different base for power and amplitudes.
Somehow we are not content with the fact that decibels express a ratio, and that... |
I am familiar with two explanations for the phenomenon of visible color.
The first is that, for any given object, there are some wavelengths of light it reflects and some it absorbs. The reflected rays reach our eyes and thus determine the color of the object from a human perspective. So if an object appears red under ... |
I'm learning about thermodynamics for the first time and have reached the chapter regarding expansion of materials due to change in temperature but an example in the book isn't adding up with the information they've provided already.
The example states that the mass of gasoline in a fuel tank in summer is less than in ... |
I'm reading up on an experiment to measure the electric potential at some point in space. There's a charged metal sphere that sets up an electric field in space. We want to measure the voltage at some point. The procedure of the experiment includes placing a flame at the tip of a needle that is connected to a voltmeter... |
I am always hearing about the high (and increasing) costs of helium, as well as the difficulty of handling it....
Are there no high(ish) temperature superconductors that can create a strong enough magnetic field?
Or are they all 'Type-II' superconductors in which 'holes' (vortices) appear in the supermagnets (weak Meis... |
I was reading Dr. Feynman's Physics Lectures Vol 1 and in the first chapter about the atomic theory, he gives the example of a piston-type container where he explains the proportionality of force and area when density remains constant. But then he proposes to double the density of the gas in the container (let it be st... |
Subsets and Splits
No community queries yet
The top public SQL queries from the community will appear here once available.