Principle Definition and 1000 Threads

Hello everyone, Heisenberg's Uncertainty Principle states that the less uncertainty there is of a particles position, the more uncertainty there has to be of its momentum. Since mass is a constant in this case, we can refer to the uncertainty of the velocity instead. I was reading a physics...

I want to obtain equation using Hamilton principle but I just couldn't figure it out; i have The kinetic energy : \begin{equation} E_{k}=\dfrac{1}{2}m_{z} \displaystyle\int\limits_{0}^{L}\ \left[ \left( \dfrac{\partial w(x,t)}{\partial t}\right)^{2}+\left( \dfrac{\partial v(x,t)}{\partial...

Homework Statement Show that it is always possible to adjust measurement units such that a; b can be assigned any values you want. This means that e.g. all van der Waals gases look exactly the same if the units are accordingly adjusted. (This is what is called principle of corresponding...

Homework Statement I have confusion. Suppose i have metal cube placed in empty vessel. I have seal tight the base of cube so that the water or any fluid can't seep below the cube. Now i pour water into the vessel. Will there be bouyancy on the metal cube ?? If i measure the weight of cube, will...

My understanding and application: Flowing blood with mass m, and velocity v has KE proportional to mean velocity squared as blood flows inside the vasculature, pressure is also exerted laterally against the walls of the vessels So, it is then reasonable to use Bernoulli's for the blood and...

Homework Statement An object is traveling at 10m/s. along an inclined surface of an angle 10°. How far does it go up the bank? How fast will it be going when it travels back down? Coefficient of friction is .15 Homework Equations Ei = Ef Ef - Ei = Eloss [/B] W = Fd The Attempt at a Solution...

I'm having some trouble with understanding Babinet's principle, which in a simple case should imply the following: ''If I send light through a single slit, then I observe a certain diffraction pattern at the screen. Now I replace the slit with a single obstruction of the same width as the slit...

Homework Statement 1) Very short laser pulses can be produced, on the order of a few femtoseconds. (look it up.) If a laser has a center wavelength of 800nm, and lasts for 20 femtoseconds, (2*10-14s) what spread of wavelengths must it have to be compatible with the time-energy uncertainty...

Dear Physics Forum, Is the Uncertainty Principle the cause of the infinite solutions to Schrodinger's equation? I get the sense it is not. Could you elaborate a little? Thanks, Mark

Hi, I have a question about the validity of Hiesenberg's principle when relativity is in action. Hiesenberg's principle tells us that simultaneous measurement of position and momentum can not be done accurately . But relativity tells us that simultaneity is relative , so simultaneous...

Hey guys, I'm studying for an exam that I have in Complex Analysis and I got stuck at the following question. Question: True/False f(z) is an analytical function in the ring 1 =< z =< 3. Also, the minimum of |f(z)| on |z|=1 equals to 1 and the maximum of |f(z)| on |z|=3 equals to 2. Therefore...

If I understand correctly, this very important principle in quantum theory says that the more precise you know the position of a particle, the less precise its momentum can be known. So this raises several questions to my mind: 1) Does this principle applies to photons? Isn’t a photon source...

Anyone know how to differentiate $$y=x^x$$ by first principles?

Hi all. In my physics class I have to give a 15 minute blackboard lecture on a topic in modern physics. I chose the uncertainty principle because I feel there is a tendency (at least at the undergrad level) to just accept what it is without proof or intuition. I would like to go into greater...

I've been reading about Fermats last principle in Feynmans lectures on physics, and he sort of goes through the derivation of Snell's law by considering a simple refraction and applying a bit of trigonometry (see photo). What I'm having trouble with is this. He states that if you take a two...

Homework Statement I know that the principle of equivalence states that a person in a window-less box will not be able to tell if s(he) is in a stationary box on Earth or in a box that is accelerating upward at a constant rate. I am assuming that the acceleration of the rocket is 9.8 m/s^2...

Homework Statement Homework Equations KVL: ΣV = 0 KCL: ΣI = 0 v = iR The Attempt at a Solution I started by removing the independent current source to leave an open circuit. Then I attempted nodal analysis at nodes v1, v2, and v3: KCL @ v1: (v1 - v2)/10 = v1/40 KCL @ v2: (v2 - v1)/10 -...

Imagine an electric dipole with charges ##+q##, ##-q##, mass ##m## and size ##d##. Assume this dipole is oriented horizontally and is sitting at rest on top of some weighing scales on earth. As the charges are at rest the weight of the dipole is just ##-mg##. But by the principle of...

I'd like to see for myself the Equivalence Principle. Would there be a commercially available test kit like perhaps a small iron and cotton enclosed in vacuum tubes and they are to fall at same time and hit the bottom at same time with indicator lights to tell if they hit at same time or at bit...

My understanding of the angular momentum quantum number is that a different number indicates a different region of space that the electron can occupy. So does the principle quantum number determine the size of that region? For example, is 2s the same as 3s in shape, but the 3s has a greater...

I am new to relativity, so bare with me. I do not want to argue against it; however, one must admit it is a rather awesomely unwieldy theory. In my self education on the subject, I am bothered by the Equivalence Principle, mainly this: An elevator accelerating through space is no different from...

Consider a particle and you measure the position with a relatively small uncertainty in a box Δx2 . And then you measure the momentum very precisely, let's say with infinite precision. Is the position then completely undetermined or is it still in a large ball of 4/3π(cΔt)3? Does the wave...

Hi, I have 16 years old, I am planning to be a physicist in the near future, and I have 3 doubts, could you guys answer to me? 1. Does quantum entanglement proves that everything is connected? http://phys.org/news/2015-01-popper-againbut.html#nRlv 2. 'The Observer Effect' and 'The Uncertainty...

Homework Statement A solid, conducting sphere of radius "a" and charge -Q is concentric with a spherical conducting shell of inner radius "b" and outer radius "c". The net charge on the shell is +3Q. Take the zero of electric potential to be at some point at infinity. a.) Use Gauss's law to...

Lets suppose device A measures the position of a particle very accurately. Device B now cannot measure its momentum to high accuracy due to the uncertainty principle. But let's suppose that neither A nor B can ever communicate their findings to the rest of the world. Now the uncertainty...

So I've been looking up things on the Holographic Principle for a while now, but there's still a few questions I have. As I understand it, the Principle says that if I drop a book into a black hole the book's information would be 3D inside the black hole and it would also be 2D on the event...

Homework Statement Without adding any Chromium based compounds, how would you manipulate the above equation to produce more CrO42- ions? Be sure to use chemical equations to show the answer. Homework Equations 2CrO42- (aq) + 2H3O+ <--> Cr2O72-(aq) + 3H2O (l) The Attempt at a Solution So my...

Here are the 2 situations: Situation A: a person floating in space far away from any mass (i.e. the person is in zero-gravity environment) Situation B: a person undergoes a free-fall from the top of a roller coaster (assuming that there's no air resistance) My question is, would the person in...

I have a question about, perhaps, GCSE level physics, if not below, which, for some reason, is not explained anywhere I've looked up. Or, at least, I didn't find any explanation. The picture above is supposed to explain the concept of superposition. It depicts a pair of one-dimensional waves...

Hi. The Lagrange equations can be derived simply by using Newton's laws and defining potential, work and kinetic energy. So that's just a mathematical reformulation of known results. Is it the same with Hamilton's principle? Is the concept of "action" and it being stationary just another...

Hello Folks, May be I am bring up the old topic again., but I've lost enough sleep over this topic. I understand that we use Von-Mises criteria for ductile material failure by comparing to yield limit and max principal stress is used to check failure for brittle materials. My question is bit...

Cl2(g) + H2O(l) = HCl(aq) + HClO(aq) (reversible reaction) 1. What would happen to the concentration of HClO if more HCl was added? Wouldn't it decrease, since the position of equilibrium then would shift to the left? 2. If NaOH was added to neutralize the acid, what would happen to the...

Homework Statement vertical rocket start: F_thrust (simple F) Δm (fuel consumed per Δt) m_tot the relative velocity of the gas w is demanded. Homework Equations vgas=v+Δv+w, w<0 m(t)=mtot-Δm*t The Attempt at a Solution rocket acceleration. F-G=m(t)*a(t) a(t)=F/m(t)-g first...

It seems to me, at least when it comes to quantum mechanics, "information" has become the most basic unit. Like, quantum entanglement works to the point that information is extracted, and one can even revert certain things by making sure the information is destroyed. Same with the discussion...

I am working through linear algebra from MITs MOOC online courses. One of the question refers to the uncertainty principle. It states: AB-BA=I can happen for infinite matrices with A A=A^{ T }\\ and\\ B=-B^{ T }\\ Then\\ x^{ T }x=x^{ T }ABx-x^{ T }BAx\le 2\parallel Ax\parallel \parallel...

Homework Statement Calculate the tension in the rope, T, in the diagram below: http://imageshack.com/a/img905/2848/yMC01l.png Homework EquationsThe Attempt at a Solution The 'beam' is a stable structure, thus the resultant forces be equal that are acting upon the beam. So, I calculated the...

Homework Statement My textbook (Advanced Engineering Mathematics, seventh edition, Kreyszig) indicates that if u1 and u2 are solutions to a second-order homogeneous partial differential equation, and c1 and c2 are constants, then u where u = c1u1 + c2u2 is also a solution, this is the...

Say we have an elevator moving through deep space at a constant velocity. We have a light emitter at the "top" of the elevator pointing towards a detector at the bottom of the elevator. We shine the light and notice that the frequency at which the light was emitted at the top is the same as...

Hi everybody. This is my first thread ever on this forum :S I'm in a first year physics class, and the other day we did a lab involving a c.c.c (current carrying conductor) and a magnet on a balance. The c.c.c was a wire which completed a circuit. One had a magnet assembly which was placed on...

http://www.sciencedaily.com/releases/2014/12/141219085153.htm It says "Here's a nice surprise: quantum physics is less complicated than we thought. An international team of researchers has demonstrated that two peculiar features of the quantum world previously considered distinct are different...

Homework Statement A small boat weighing 1000 N has a surface area of 3 m^2. It floats only 5 cm above the water level when in a fresh-water lake. How high out of the water will it ride in a salt-water lake? Assume the surface area of the boat does not change as it rises (salt water has a...

Hi everyone, I'm taking my second semester of calc based physics this coming spring. I have a question in optics stemming from my reading of Feynman's lectures on physics. He gives a rough definition of Fermat's principle of least time as follows: "... out of all possible paths that it might...

6 people are invited to a dinner party and they are sitting on a round table. Each person is sitting on a chair there are exactly 6 chairs. So each person has exactly two neighboring chairs, one on the left and the other on the right. The host decides to shuffle the sitting arrangements. A...

Homework Statement how to prove the potential energy principle? how do you make sense of the potential energy principle ie -dU/dX = F(x). What does the principle really mean? Homework Equations -dU/dX = F(x) where U is the potential energy and F the force. The Attempt at a Solution Not...

Background: I am an upper level undergraduate physics student who just completed a course in classical mechanics, concluding with Lagrangian Mechanics and Hamilton's Variational Principle. My professor gave a lecture on the material, and his explanation struck me as a truism. Essentially, he...

Homework Statement A load of 10 kg is pulled up a lubricated slideway, set at an angle of 30° to the horizontal, such that the load is accelerated from rest to a velocity of 1 m/s whilst traveling up the plane through a distance of 1 m. The frictional resistance to this motion is 10 N and g =...

Is it true that if time stood still it would violate the uncertainty principle. therefor if you traveled at the speed of light time stands still and you would violate the uncertainty principle. if this is true does that sugest that QFT sets a lower max speed that matter can travel at than what...

Hi. I am no physicist but I am trying to know something about the holographic principle. As I understand, everything is happening in a surface and our three-dimensionality is an illusion of our senses. On the other side, string theory assume the existence of 11 dimensions. Are the two theories...

Homework Statement Question: What minimum volume must a slab of ice in a freshwater lake have for a 50.0kg woman to be able to stand on it without getting her feet wet? Homework Equations Archimedes principle...

Homework Statement A balloon used for a physics experiment has a radius of 3.15m and is filled with helium. The total mass of the balloon is 15.2kg and the density of the surrounding air is 1.28 kg/m3. a. How much buoyant force is acting on the balloon? b. When the balloon is released from the...