Principle Definition and 1000 Threads

. Homework Statement A block oak weighs 90 N in air. A piece of lead weighs 130 N in water. The two weigh together 100N in water. Calculate the relative density of the wood.Homework Equations F=mxg F(archimedes)= density x Volume x g The Attempt at a Solution F (g)oak = 90 N F= mxg m= 90N/9.81...

I used a tub for my hemorrhoid. I learned the archimedes principle which the buoyant force is equal to the mass of water displaced. The tub was filled with water 4/5. I accidently farted in a tub and suddenly the water flew into the hole which is located on the top of tub.does the fart gas...

A well known math theorem says that - if the spatial dimension is odd - D'Alembert equation gives rise to a solution containing a term which is completely supported on the light cone. A mathematical wrap up could be the following: "in dimension 3 (and in fact, for all odd dimensions), the...

Homework Statement 35m^3 of a boat's volume is submerged under water. What does the boat weigh? The boat is 14 metres long. Homework Equations pVg=mg The Attempt at a Solution pVg=mg pV=m m=pV=1000*35 This is what my teacher said, but I don't understand it. The submerged volume of the boat...

In both quantum and general relativity theories we are used to provide results in the "limited" conditions to demonstrate a correspondence between new and old formalism. For instance deflection of light of a star due to Sun in GR is double the amount given in classical theory. Yet I have...

Observables are paired up in the uncertainty principle such that we can't measure both to a high degree of accuracy. Specifically, ## \sigma_x \sigma_y>\frac{\hbar}{2} ## where ## \sigma_x ## and ## \sigma_y ## are the standard deviations of our measurements. I've got two lines of questions...

As we know, the Fermat's principle states: Light takes the path of least time. I wonder whether Fermat's principle can be derived from Maxwell equations. If it can, then Fermat's principle is included in Maxwell equations, or Fermat's principle is not an independent postulate.

First postulate (principle of relativity) and 2. Second postulate (invariance of c), affect not we continue investigating new things?

Andrei G. Lebed, "Breakdown of the equivalence between gravitational mass and energy for a composite quantum body," http://arxiv.org/abs/1404.4044 [corrected a mistake in the following paragraph] He seems to argue that hydrogen atoms moving from one region of space to another, with a different...

I have had some criticism on a post of mine in another topic. Since I don't want to pollute that thread with my own discussion, and since I am a layman and am really curious about the answer, I'll pose my question here. Consider two polarisation-entangled photons A and B measured by Alice and...

what will be the scenario if Heisenberg's uncertainty principle is applied at macroscopic level?

if we have a solid conducting sphere with charges around it, then the elctric field inside the sphere is zero otherwise the electrons of the sphere would not be in equilibrium as there would be a net force acting on it. however if its a hollow sphere then why does the electric field inside the...

Hello forum, please take a look at the following picture: It's a salt solution, with increasing refractive index, as you go down the solution. How can I explain this with Fermat's principle? Let's set the starting point A to the point, where the laser beam penetrates the left wall of the...

Can you give me some examples, link of correspondence principle use in life. All I have found out are theoretical examples such as Bohr's model... If I understand right, correspondence principle says that simple equations used for classical examples with a few data and quantum equations used...

I can not understand what exactly this principle says.while reading a book about it ,it was written that einstein abolished gravity by saying the lift is free falling can some explain clearly what does that mean?

I was reading some simplistic explanations of Pauli's Exclusion Principle (PEP) to explain a group of non-science people, and I came across this: For Fermions, even as pressure builds, no two can be located in the same energy state. This causes them to "stack up" in effect. Only under great...

I have to derive I did all the way but stuck with the ">=" to "=" sign. what is the logic behind it ? is it safe to write "approximate" while taking the square-root on both side ? or the energy term "V" has gone during the calculation so it has only momentum "p" ?

Firstly, I am just a very interested layman so please forgive my ignorance and non mathematical approach. As I understand it, the cosmological principle states that on larger scales the universe is homogeneous and isotropic. So could someone help me to understand the following: 1) Does this...

Upon a measurement of the position, the wavefunction collapses to a spike centered at x0 https://farside.ph.utexas.edu/teaching/315/Waveshtml/img3240.png I encounter similar spike pictures numerous times, but there is an uncertainty in position , it can't be a spike right. First thing I see...

Hi according to Huygens principle every point on the wave front acts as a spherical source. so if a we emit monochromatic light on a screen without passing light from grating, we should see interference pattern but we don't. why don't these spherical waves interfere with each other? is this...

Multiple_Authors submitted a new PF Insights post Does the Heisenberg Uncertainty Principle Imply Energy Nonconservation? Continue reading the Original PF Insights Post.

Here is what I understand of the equivalence principle. However, given that the concept is still a bit cloudy to me, please tell me if I am wrong: The equivalence principle is a phenomena where all inertial objects experience the same laws of physics. In other words, if you were going at...

Homework Statement Homework EquationsThe Attempt at a Solution Applying Archimedes priniciple the force exerted by liquid on the upper hemisphere would be ## F = \frac{2}{3}\pi R^3 \rho g## . Now I am not sure , what does it mean by force due to gauge pressure ? Any help is appreciated ...

I was working on derivation to find the witdh of principle maxima in n slit diffraction Angular width=2Δθm=2λ/(Ndcosθm) Where d:distance between slits θm:angle at which mth order principle maxima is present. N:no. Of slits #in the diagram given below why the minima just adjacent to mth...

Hello, Bernoulli principle describes the flow of a fluid for steady, incompressible flow along a streamline. But it is said for a particle of a fluid along a streamline. My question is a particle of fluid refers to a molecule or a group of molecules? Thank you

Homework Statement Let A be the algebra \mathbb{Z}_5[x]/I where I is the principle ideal generated by x^2+4 and \mathbb{Z}_5[x] is the ring of polynomials modulo 5. Find all the ideals of A Let G be the group of invertible elements in A. Find the subgroups of the prime decomposition.Homework...

Equivalence principle says that gravitational forces are equivalent physically to inertial forces. Can someone explain what is meant by that and how was it concluded?

Homework Statement A ray travels as shown in the image attached below. In this case, Fermat's principle may be written as ##A =\frac{n(1+ay)}{\sqrt{1+(y')^2}}## Where y' is dy/dx, n is the index of refraction and A is a real constant. The trajectory of a ray of light is given by ##y =...

My question is how does the uncertainty principle relate to quantum computers? Does it hinder the theoretical production of a quantum computer?

Urs Schreiber submitted a new PF Insights post Higher Prequantum Geometry II: The Principle of Extremal Action - Comonadically Continue reading the Original PF Insights Post.

Backreaction has the story: http://backreaction.blogspot.com/2015/09/no-loop-quantum-gravity-has-not-been.html debunking this article: Violation of the Holographic Principle in the Loop Quantum Gravity Ozan Sargın, Mir Faizal http://arxiv.org/abs/1509.00843 and also showing the authors behaving...

Hey all, I am reading Goldstein and I am at a point where I can't follow along. He has started with D'Alembert's Principle and he is showing that Lagrange's equation can be derived from it. He states the chain rule for partial differentiation: \frac{d\textbf{r}_i}{dt}=\sum_k \frac{\partial...

sir, what if we use Heisenberg's uncertainty principle to explain double slit experiment? i was reading about uncertainty principle for last few days n i was reading about double slit experiment and i realize that we can explain why we get electrons everywhere on the screen (getting...

Homework Statement I need to find three potential reasons for my .5% error in a lab where I used the Archimedes Principle to measure the density of Iron. We only used a graduated cylinder full of water and an iron mass. I measured the water level from the meniscus. We used two different...

Principle of least action states that the particle choose the path which optimizes its action.Where the action is defined by S=t1∫t2(L)dt and L is the Lagrangian of the system.This leads to δS=0 and it is a condition to optimize S. I will summarize what confuses me about this principle in a...

Use inclusion-exclusion to find the number of ways to arrange the six numbers 1, 2, 3, 4, 5, 6 such that either 1 is immediately followed by 2, or 3 is immediately followed by 4, or 5 is immediately followed by 6. I believe that this can be solved using unions. By setting the sets to be the...

I don't even know what is the general name for the thing whose specific name I am trying to find out, but in an algebra question, say 3x = 6y, there is the "assumption" that by dividing both side by 3, we will get x = 2y and this equation is as correct as the original one. What is thing that...

How do we use Fermat's principle of least time to explain the required shapes of lenses and mirrors?

Homework Statement A small tube is connected to the top of a larger one and the whole thing is filled with water. The small tube has height a and the larger tube has height b. What happens to the pressure at the bottom of the larger tube as (1) a is varied, and (2) a is held constant but the...

Good day all, A question that I haven't really found the answer for yet: "Whom did first come up with the idea of the cosmological principle?" I almost looked everywhere for the answer but still cannot find it. Was it Friedmann or Lemaitre? Or was it some other great physicist? But there...

Homework Statement Can somebody please tell me exactly what archimedes prnciple is? Homework Equations The Attempt at a Solution [/B] So, I watched this video: . Apparently if we have a cube in a bucket of water then the mass of the whole cube is equal to the mass of the displaced water...

Hi all, I am reading an article about uncertainty principle. If we consider a Gaussian wave packet which standard deviation of momentum ##\sigma_p##. The uncertainty principle states that the multiplication of variance of x and variance of p is larger or equal to half ##\hbar## ##\Delta...

Hi, I'm reading Schwartz's book "Quantum field theory and the standard model", section 7.3.2., page 95 (https://books.google.com/books?id=HbdEAgAAQBAJ&printsec=frontcover&source=gbs_ge_summary_r&cad=0#v=onepage&q&f=false) where he's talking about disconnected diagrams, the ones that have subsets...

Let $\left(X,d\right)$ be a complete metric space and suppose that $f:X\to X$ satisfies $d\left(fx,fy\right)\le\beta\left(d\left(x,y\right)\right)d\left(x,y\right)$ for all x,y $\in$ X where $\beta$ is a decreasing function on ${R}^{+}$ to $[0,1)$. Then $f$ has a unique fixed point. The...

İn some fixed point theory books, I saw an expression...But I didnt understand what this mean...Please can you help me ? " It was important in the proof of banach contraction principle that the contraction constant "h" be strictly less than 1. Than gave us control over the rate of convergence...

Two days ago, I have opened theme about fine-tuning on which I got good answers... Now, there is another topic, on which I have question... The reason why I am asking this question here, is because I want to get correct answer... Internet is full of trash and misinformation, and this is a...

If we devise a physical system and perform an observation of some physical quantity, how can we infer that this quantity is related to the eigenvalues of the momentum operator -ih d/dx ? Another way to look at it. Suppose you were handed the theory of quantum mechanics and that you already had...

I'm interested in self-learning computer science; however, I primarily only want to know the information that produces 80% of the results and mostly ignore the rest of the fluff. There's no real deadline for me. There's things that are important, yet there are also things that are cool to know...

Hi. Assume we have a large number of identical boxes of some finite length ##l## and with infinite potential walls. Let's prepare them all in the same momentum eigenstate. Since for eigenstates ##\Delta p=0##, by the uncertainty principle ##\Delta x## should go to infinity. However, since the...

Homework Statement I don't get how you can use x and p instead of delta x and p in Heisenberg's principle. Also why is it just h bar? Isn't it supposed to be h bar/2? Problem 2-iv Homework Equations delta x* delta p >= h bar/2 The Attempt at a Solution I tried to deal with this problem but I...