All Questions

134,106 questions
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Lifting weight with MA 1 pulley

If you have a pulley system with a mechanical advantage of 1, is it possible to lift more than your weight?
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Wigner Seitz cell

While searching the difference between primitive cell and unit cell I have seen that "Primitive unit cells contain only one lattice point, which is made up from the lattice points at each of the ...
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Force required to lift a block

Let us consider block of mass $m$ hanging by rope with force $T$. When no other horizontal and vertical forces are acting on a block, the block is at equilibrium if $$T=mg.$$ And if the rope is pulled ...
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Why bicycles' rims are bent after winter? [on hold]

I've noticed that the rims of many bicycles which are parked in the street during the whole winter are heavily bent. I'm wondering what causes this deformation? Typically, this happens to rather cheap ...
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Centre of mass frame [on hold]

Say I have two bodies A(mass 2m) and B (mass m) connected with a string (taut) and I project A with some velocity v perpendicular to AB . So is there any way to find the Tension in the string? I ...
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Scintillator decay time=1000 nsec,does that mean dead time is really high?

What I'm really confused about is, say my scintillator is really slow, and has a decay time of about 1000 nsec. Does that mean, if one neutron is being read by the electronics, for that particular ...
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Acceleration Problem [on hold]

I am doing kinematics in grade 11 physics and I've come across this really tricky question. Since there is no mention of time anywhere (and it asks for ... vs time graphs, I have no idea where to ...
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Is a quantum harmonic oscillator always infinite dimensional?

Let us assume we have a quantum particle in a harmonic potential with the Hamiltonian $$H = \sum_i i \omega_i \mid i\rangle\langle i\mid$$ If I am not mistaken. Now when talking about harmonic ...
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How much fuel goes to wind resistance caused by the gap between the cab amd trailer of a semi?

How much fuel goes to wind resistance caused by the gap between the cab amd trailer of a semi?
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Superposition of large mass of metal

If one could put tons of iron in superposition, and collapse that superposition, would there be detectable space-time distortions? EM? Like what if there was Schrodinger's "metal" I guess is what im ...
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Visualization of a time-dependent Potential

My questions come from reading this paper about charging quantum particles. We have a quantum particle in a harmonic potential which we will charge using a cyclic unitary processes. Cyclic in this ...
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Can we create new physics through moderately brute force computing?

So my argument for this is that the expansion of knowledge in any field of physics depends on what is previously known, and what we physicists express or knowledge as equations. So here's what I ...
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According to power rule R=V2/P shouldn't this claim be false?

"As the power dissipated in a bulb is I2R the bulb with the higher resistance (lower power when connected directly across the supply) will dissipate the greater power."
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Transform mixed vielbein expressions to $\sqrt{-g}$ times traces in massive gravity?

In the Massive Gravity review by Claudia de Rham the massive gravity action is given by with mass potential in vielbein formulation. Equivalently, the same action can then be described by with I ...
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Conceptual understanding of the Quantum Harmonic oscillator

First: When we consider a quantum particle in a harmonic (quadratic) potential we say that this particle is a harmonic oscillator, because it behaves like one. Is this correct? Now let us assume our ...
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How is the standard model actually quantized?

The standard model Lagrangian is well known. But there are several ways to quantize a theory starting from the Lagrangian. In particular there are several ways to quantize gauge theories (e.g. ...
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Is wire-wrap spacing and consistency important in electromagnets?

I'm creating an electromagnet (several, actually) to test a hall effect switch. I understand that more wire wraps (turns) increases the magnetic B-field, as does more electric current. Adding more ...
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Rand-walk/Brownian-motion on 2D lattice

I started to learn stochastic processes this year. Only had two classes, but I already have some problem. We learned about Einstein's and Langevin's description of Brownian-motion and now I need to ...
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Relativistic Electric Potetnial

Suppose you have a particle of charge q circling the z axis in the xy plane. The orbit is centered at the origin and has a radius of $r_0$. The angular frequency of the orbit is $\omega$. Position of ...
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Voids in steel?

I have found black areas in the the surface of some steel. Are these voids from the original manufacure or are they created by corrosion? This one is approx 1mm x 0.5mm.
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Why is the graph for the flux density of a copper ring, when a magnet falls through, not linear?

In an experiment where a magnet is falling through a wire, the flux density is presented by the top graph in the image. Why is the graph not a straight line like the one below it? I thought that if ...
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What do we mean by curly braces in an atomic configuration?

What do the '{` mean in atomic configurations e.g: 1s(2)2s(1)2p(2){3P}3p(1) 1s(2)2s(2)2p(3){4S}3p(1)
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Trouble with trigonometry for elastic collision in two dimensions

I have these two equations that I am trying to substitute and solve: 1) $4 = v_1^{'}\cos\theta_1 + (1.69)\sin\theta_1$ and 2) $0 = v_1^{'}\sin\theta_1 + (1.69)\cos\theta_1$ $\theta_1$ and $v_1^{'}$...
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Electromagnetic field conversion in non-inertial frame

I found these equations for electromagnetic field conversion in inertial frame for non relativistic case. If I have permanent static magnetic field with 3 components $B_x, B_y, B_z$ and permanent ...
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Spectral representation of a BCS gap function

I am playing with the spectral representation of a BCS gap function and I have trouble verifying causality properties. I find a divergence and I don't know what is the problem. Assume the gap ...
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Deriving Canonical Transformation from Generating Function using Principle of Stationary Action

In Hamill's "A Student's Guide to Lagrangians and Hamiltonians", section 5.2, the equations for a canonical transformation $(q,p) \to (Q,P)$, induced by the generating function $F(q,Q,t)$ are derived ...
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Mathematical expression of impulsive forces during a collision

I'm facing with problem regarding collision between bodies. Specifically, I need to understand the impulsive forces that arises during a collision. Sometime ago, I posted two questions (this and this) ...
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Will making the surfaces extra smooth increase friction?

If we make the surfaces enough smooth that all asperities are removed then the two bodies in contact may act like a single body making frictional force infinte. I know this is practically impossible ...
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Why in a DC series Circuit do bulb attached in parallel to highest resistance glow brightest?

I was performing an experiment in which there were five resistances connected in series and then I connected a bulb with each of the resistance. Each bulb was connected in parallel to each resistance ...
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Question about angles for elastic collision in two dimensions

While working on problems for elastic collisions in two dimensions, I've encountered the equations: $\theta_1$ + $\theta_2$ = 90° and $\theta_1$ - $\theta_2$ = 90° from different resources. ...
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My Elasticity Doubt

I had a question on elasticity which looked something like this. {: .center} We have small beads of mass say $m$ and Mass of rod say $M$. Now we need to find the extension in the rod after the beads ...
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Do materials gain compressive or tensile strength if compressed?

If I take a block of play-dough and squish it down, it becomes harder to pull apart and push together. Does this same phenomena hold for "real world" materials? If I take a block of steel and ...
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Difference between linearly polarised and plane polarised wave

To explain polarisation, my book gives an example of a transverse wave in a string, and explains as: Since each point on the string moves on a straight line, the wave is also referred to as a ...
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Angular momentum coupling

I read about angular momentum coupling on wikipedia and there are a few things i dont understand. What does this mean "spin and orbital angular momentum of a single object belong to different Hilbert ...
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Question about full wave bridge rectifier

Sorry if this is a stupid question, what I know is when a diode is forward biased, it conducts current, when it is reverse biased, it acts as an open branch if its $PIV \geq V_{in}$ But in this ...
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Landau Theory of fluctuations

With respect to chapter 12 in the book Statistical Physics(Part 1) by Landau and Lifshitz, I am currently stuck at the intepretation of Fluctuation theory that Landau provides. In the neighbourhood of ...
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Units of momentum eigenstate probability current have an extra density in momentum

The units of probability current should be $m^{-2} s^{-1}$, a rate per area, basically. However, on page 530 of Shankar's Quantum mechanics book, we are speaking in terms of the momentum eigenstate in ...
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Can suggest me one best physics book for concept building, make roots of science strongest and of my level? [on hold]

I'm class 10 student. It should not be too easy too hard. And new deeper concepts that i can't get in academics.
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Question about the geometric structure of Newtonian mechanics

My point here is about the mathematical structure of Classical pre-relativistic physics and general relativity (GR). It became more clearly, after GR, about the fact that pseudo-riemannian are a nice ...
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Dependence of heat transfer rate on acoustic boundary layer thickness

I have generated a sine wave acoustic signal of constant amplitude and different frequency (i.e. 50Hz to 250Hz). At low frequency i am getting higher evaporation rate. However, at low frequency ...
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How to draw diagrams of Path, velocity and time for a complex problem?

What does an approach or a solution strategy look like for the following problem: Two point-shaped bodies with the masses m_1=100g and m_2=200g are connected to a string of 30 cm length and lie on a ...
70 views

Ernst Mach vs. Einstein

In the Ernst Mach wikipedia page, Einstein seems to be influenced by Ernst Mach. But it says In 1930, [Einstein] stated that "it is justified to consider Mach as the precursor of the general theory ...
32 views

Moment of inertia and counterweight

I need help regarding moment of inertia - i have zero clue on this topic. I have 2 sets of problems which i am told to use moment of inertia ( which i don't get it ) 1.I have to use counterweight ...
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Trouble in proving geodesic action invariance under diffeomorphism

In this post Diffeomorphism invariance and geodesic action it is said: You found (by computing in local coordinates) that this is invariant under a diffeomorphism $\phi: M \to M$. This statement ...
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Question on force invariance under the Galilean Transformations (GT)

By the Galilean transformations, one can easily derive that two different inertial observers 1,2 always measure the same forces. That is:  \vec{F_1} \ \left(\vec{r_1}, \frac{d\vec{r_1}}{dt_1},t_1\...
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Why does a body when kept on the inner surface of a cone undergo circular motion,while it undergoes linear motion when kept on a inclined plane?

Same forces are acting on the point-mass in both cases, and the Normal Force can be balanced by the weight Mg of the body in the case of the smooth cone in the same way it cancels in the case of ...
111 views

Is the statement true about mass?

According to newton laws if something is in uniform motion and equivalent force is equal to zero then its mass cannot change. I am just a school kid. I just entered physics so please explain kindly ...
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Is light penetration through water affected by water pressure?

Does water pressure affect propagation of light through water?