Principle Definition and 1000 Threads

I want to know why does the buoyant force equal to the weight of fluid displaced and how the weight of water displaced is equal to the weight of object for free floating objects? What's buoyant force by the way?

As a result of some precise experimental data, we now know that the mass of the quark is not naively 1/3 the mass of the proton. The most recent estimates for the mass of the quark is: Masses of the current quarks: = 2 - 8 MeV/c2 = 1.0 - 1.6 GeV/c2 = 168 - 192 GeV/c2...

Homework Statement Q1. Briefly explain the relevance of the Pauli exclusion principle for the structure of the periodic table of the elements. Q2. What is the maximum number of electrons that can be located in an atomic subshell with quantum numbers n and L? Briefly expain your answer...

I have been puzzled by this for years, so I would welcome some enlightenment. It seems that Einstein was enamored with Mach's principle while searching for GR, but in the end GR does not seem compatible with it - or rather has nothing to say about it. What I mean is that the proverbial...

Hi; Normally, the solar panel charges a 12V battery and battery provides backup to load via an inverter. The solar panel produces voltage which is directly proportional to sun light. So early in the morning and in evening, solar panel produces less voltage which is insufficient to charge the...

I have to be honest, the principle of least action seems to me more of a religious claim one takes on complete faith, though of course I'm hoping this is just because I don't understand it. I tried to explain this to a friend suffering through a mechanics class & was literally pushed to say 'one...

Have i done it correctly?

First off, just clarify that I have a very, very superficial knowledge of Physics, so my apologies if my question is based on an obvious misunderstanding of the basic principles underlying the second law of thermodynamics or if it has a rather simple answer. The doubt that I have is related...

Homework Statement . I want to prove that there is one solution for e^z-z in every shifted copy of the fundamental strip by applying the argument principle to the boundary of a rectangle −M≤Rez≤M , 2kπi≤Imz≤2(k+1)πi for large M and integer k . I need help in using the...

Hi to all, i will appreciate your help in this. This is the situation: I have a tank, with a water column in it. This tank at the bottom has an "ideal" seal (a seal that permit the passing of object from bottom to upwards, but not the water to fall down.) In this system i have sphere with...

what is the whole concept of the superposition principle?

Sorry for some probably very basic questions, but here goes. If gravity equals acceleration, how is the Earth's gravity defined by acceleration? If an accelerating body distorts spacetime, as described in Einstein's thought experiment about a light beam shined through an accelerating box...

Homework Statement Explain why the number of microstates W in Boltzmanns principle, is W = ƩNi! / ∏Ni! when i ideal gasses are mixed at constant volume and temperature. Ni is the number of particles of component i. Homework Equations S=klnW , where W is the number of microstates...

I really can't understand the uncertainty principle,and now there are some experiment that violate the uncertianty principle, I need deepen understanding of quantum uncertainty,who can give me all the information about the uncertainty principle,such as new ideas,related study or books,thanks

Virtual work principle states: δW = \sum^{N}_{i=1}\vec{F}_{i}\centerdot δ\vec{r}_{i} And from this, we can see that if a system is to be in equilibrium we have δW = (\sum^{N}_{i=1}\vec{F}_{1} \centerdot \frac{\partial \vec{r}_{1}}{\partial q_{1}})δq_{1} + \cdots = 0 Where did q come...

What is the reason/ explanation (possibly in a nutshell!) that all the physical information of a volume can be encoded in the surface surrounding that volume?Because, you know, that sounds silly, at first! I browsed some introductory sources, but could not find any quick answers. Also, if...

When I have a reaction CO(g)+2H2(g) <=> CH3OH if I increas the concentration of CO, the equilibrium will be shifted to the right so more methanol will form. However, in that process won't the concentration of Hydrogen gas decrease? So won't that cause a change in equilibrium as well? If so, how...

Homework Statement Calculate the derivative of f(x) = x^3 - 3x^2 Homework Equations (f(x+h) - f(x))/h The Attempt at a Solution Just wondering if someone can check my solution. (f(x+h)- f(x))/h= ((x+h)^3- 3(x+h)^2- (x^3-3x^2))/h = (x^3+ 3x^2 h+3xh^2+ h^3-3(x^2+ 2xh+ h^2 )-...

Homework Statement Let A be an 8x8 Boolean matrix. If the sum of A = 51, prove there is a row and a column such that when the total of the entries in the row and column are added, their sum is greater than 13. The Attempt at a Solution I considered a selection of one row and one column...

Ok, so I have had a lot of spare time and started pondering the things of the universe. Mainly problems looking at time dilation, mass dilation, length dilation and gravity. So one day I came up with a question that I have been unable to answer and I wonder if it is answerable or if there are...

The derivation of the momentum/position Heisenberg Uncertainty Principle (HUP) is based on the statistical interpretation which says that if we have a lot of quantum systems in identical states, and measure the momentum in half of them and get a distribution with standard deviation σp, and...

If we take a narrow aperture(such as the one used in the double slit experiments) and attach a length of optical fibre to it, surely now we know the position (confined by the width of the fibre) and also the momentum(defined by the direction of the fibre). How does the uncertainty principle...

Homework Statement Let C be a regular curve enclosing the distinct points w1,..., wn and let p(w)= (w-w1)(w-w2)...(w-wn). Suppose that f(w) is analytic in a region that includes C. Show that P(z)= (1/2\pii)∫(f(w)\divp(w))\times((p(w)-p(z)\div(w-z))\timesdw is a polynomial of degree n-1...

Hey everyone, I started reading up on GR a couple of days ago, and I'm somewhat stuck on the concept of a free-falling IRF. I understand that an observer on a free-falling small spaceship would experience the laws of physics in a rather simple form, eliminating the need for a force of gravity...

Hi everybody. I have a quick question regarding the relationship between the uncertainty principle and the measurement postulate. According to the former, the higher our certainty is about the position of a particle, the lower our certainty is regarding its momentum, and vice versa. This...

I am trying to understand Gaussian curvature. This led me into looking at principle curvature. Now If one takes a look at the picture of the "Saddle Surface" on Wikipedia here: http://en.wikipedia.org/wiki/Principal_curvature I see that at the point p on the saddle where curvature goes both...

This may be a dumb question, but I am still new the the concept of the quantum world... If we can't measure position and momentum precisely at the same time, why can't we use 2 detectors? One to measure position, and one to measure momentum. Have them take the measurement at the same time, and...

A Macrocosm thing, example a car, can be exist two different places in the same time ?

The typical energy needed to ionise an atom is around 5 eV. Use the Uncertainty principle to estimate the size of an atom. Homework Equations E=mc^2 E = p^2/2m Δx.Δp ≥ h/4π The Attempt at a Solution So I got the mass rearranging E = mc^2 m = 5*1.6*10^-19 / (3*10^8)^2...

We have an electron pulse of width 1 nanosecond and with kinetic energy of 1keV. We have to calculate Δx and Δp. I have a question regarding this problem. If they give us the kinetic energy of the electron pulse then we know exactly the momentum right? And so the uncertainty of momentum would...

The principle states: δxδp≥h/4π I understand what it means and I've seen in proven both theoretically and expiamentally, so I am not questioning the inequality here. My question is: If there was a very narrow tube that had a vacuum inside it and a laser attached at one end that shoots...

Fermat's principle is the "path of least time principle" or we can say that "he path a light ray takes is a local minimum". Quantum physics also says that the light take (test) all possible paths and only the minimal remains. Is it working in special cases like this too? Let's examine the fig...

Heliocentrism is a main example of how a physical law changed due to the Copernican Principle - that is, that we as humans on the Earth are not privileged or special in the universe. Are there many other examples from the history of science where a major advance in the development of a...

Hello, I have the following question: Physics books say that in order to see diffraction you need a wave to encounter an object that is comparable in size to the wavelength. This is presumably the reason why light does not bend through an opened door but sound does. My question is, what...

Consider the Schrodinger equation with the step-function potential V(x)=\begin{cases} 0, & x<0 \\ U, & x>0 \end{cases}\qquad . A pulse with E>U comes in from the left with unit amplitude and undergoes partial reflection. The reflection has an amplitude (ignoring phase) that is given by the...

Hi guys, Could anyone explain Bernoulli's Principle to me so that it makes sense from an alternative point of view? http://hyperphysics.phy-astr.gsu.edu/hbase/pber.html I can make sense of the maths but I'm trying to understand what actually happens so I can visualise it. At first...

Hey Guys, I have got a question. English is not my first language. Is the "equal-probability-principle" the same as "the equal-a-priori-probability-postulate"? Do both names describe the same process? Thx Abby o:)

Does string theory, in principle, answer why matter comes in "chunks"? Does string theory, in principle, answer why matter comes in "chunks" of the same amount (say the mass of an electron or muon), and why the energy in the electromagnetic field of a given frequency also comes in a "chunks"...

I have the following differential equation which I obtained from Euler-Lagrange variational principle \frac{\partial}{\partial x}\left(\frac{1}{\sqrt{y}}\frac{dy}{dx}\right)=0 I also have two boundary conditions: y\left(0\right)=y_{1} and y\left(D\right)=y_{2} where D, y_{1} and y_{2} are...

I was told that the pauli exclusion principle states that no two electrons in an atom can have the same quantum numbers is it ture need answers!

I will write a program about principle bernoulli, but i have a problem. My input data: Pressure(p1) = 1000 Cross-section(A1) = 1 Velocity(V1) = 1 Cross-section(A2) = 0.5 Velocity(v2)= (V1A1)/A2 to simplify: h1=h2 i'm counting the pressure p2 : p2 = p1 + 0.5*v1*v1 - 0.5*v2*v2...

Homework Statement Hi PF! I am studying from a book - A first course in probability by Sheldon Ross, and I have came across this section whereby the are trying to prove the upper bound (equations 4.1 and 4.3) and lower bound (equation 4.2) of the inclusion-exclusion principle from basic...

What is the scope of Pauli's exclusion principle? When we say two particles in a system cannot have the same quantum state, how do we choose the system?

Homework Statement If the cord is subjected to a constant force of F= 300 and the 16kg smooth collar starts from rest at A, determine the velocity of the collar when it reaches point B. Neglect the size of the pulley. Homework Equations (\frac{1}{2}mv12) + \sumU1-2 =...

I'm not certain as to the true meaning of the Heisenberg Uncertainty Principle, and wonder if anyone can provide insight. I understand that there is a reciprocal relation between the certainties as to the position and momentum of a particle such as an electron; the more precisely position is...

How do fermions, which have vast amounts of empty space, know not to occupy the same space as another fermion? Do physicists say that the two fermions become entangled and that is what enables them to be "aware" of the "existence" of the other fermion? Is entanglement used as an explanation...

All of the statements of Heisenberg's uncertainty principle that I've read seem to state that there is a fundamental limit on the precision to which you can measure the values of conjugate pairs (like position and momentum) at the same time. So is this simultaneity necessary? I ask because...

Homework Statement Show that (\Delta A)^{2} = \langle \psi |A^{2}| \psi \rangle - \langle \psi |A| \psi \rangle ^{2}\\ \phantom{(\Delta A)^{2} }=\langle \psi | (A - \langle A \rangle )^{2} | \psi \rangle , where \Delta A is the uncertainty of an operator A and \langle A \rangle is the...

What is the physical working principle of SRR's ? How do they result in the negative permeability at a macro level? (either of explanation or decent links will do!) Thanks :biggrin:

At our QM intro our professor said that we derive uncertainty principle using the integral of plane waves ##\psi = \psi_0(k) e^{i(kx - \omega t)}## over wave numbers ##k##. We do it at ##t=0## hence ##\psi = \psi_0(k) e^{ikx}## \psi = \int\limits_{-\infty}^{+\infty} \psi_0\!(k) \cdot...