Explain Definition and 1000 Threads

Homework Statement A 55kg mass is tied to a massless rope wrapped around a solid cylindrical drum. The drum is mounted on a frictionless horizontal axle. When the mass is released, it falls with acceleration 1.0m/s^2 . Find the tension in the rope. my answer : 484N the way I got is...

As I understand it, when Schroedinger's "box" is opened, then a dead cat comes into existence in one universe and a live cat in another. However, in a variation to this experiment, in which there is say a 10% chance of the cat living and 90% dying, when the box is opened does one live cat come...

My teacher had a long metal pole (I believe it was aluminum) and said that it was NOT magnetized. He put a magnet up to the side of the pole and it did not stick, and he dropped a marker through the top of the pole and the marker came out the bottom at a normal rate. However, when he took a...

Although Albert Einstein had explained the new picture of gravity through his theory of general relativity, by explaining that gravity is the warping of spacetime, did he explain why mass actually warps this fabric of spacetime?

Can anyone explain this "self healing" mystery. Can anyone think of any type of failure mode in an electronic component that could account for the following weird case of my self healing LCD monitor. ---------------------------------------- I've got this LCD monitor that's got a weird...

It appears that the Dark Energy concept was born out of a need to explain the two major observational phenomenons (increasing rate of expansion of the Universe and the faster-than-expectated-rotation of the galactic outer-rim). If I'm not mistaken, this also has to do with gravity seemingly...

If you can answer any of the questions below, your help will be greatly appreciated. There's an equation from E&M (I believe the definition of the antisymmetric field tensor) that reads: F_{\mu \nu} = \frac{\partial A_\nu}{\partial x^\mu} - \frac{\partial A_\mu}{\partial x^\nu}...

I'm not going to blame anyone except for the fact that I'm probably a slow learner. Can somebody explain some of the things I'm learning in layman terms? That way I can have some context when I'm reading about them. Right now, the things I'm reading have no meaning, so it's really hard to...

I have become very interested in physics and astronomy recently and have started dabbling. I have been reading about curved space time and its association with gravity. I've also been reading about time as it is related to travel at the speed of light. Can anyone explain the concept of...

My professor just told me that if \Delta x is small, then we can expand L(x+\Delta x) as follows: L(x + \Delta x) = L(x) + \frac{d L}{d x} \Delta x + \frac{1}{2!} \frac{d^2 L}{d x^2} (\Delta x)^2 + \ldots, where each of the derivatives above is evaluated at x. Could someone please...

The integral is \int_0^{f(E)} \frac{\cosh \alpha x}{\sqrt{1-\beta \cosh^2 \alpha x}} dx, where f(E) = \frac{1}{\alpha}\cosh^{-1}(\sqrt{\frac{1}{\beta}}), \alpha > 0, and 0<\beta<1. The integral has proven very difficult to evaluate. Every time I plug it into Mathematica with values for...

Hey guys, I was just wondering what the difference between these two statements are: V¯(x) = ± 4 V¯(x) = - 4 ---> does not exist. This is the quote from my text, "...we remind you of a very important agreement in mathematics. The square root sign V¯ always means take the positive...

Can someone please explain this remark in Landau-Lifshitz's *Mechanics* about fields? On pg. 15, it says that "individual components [of momentum] may be conserved even in the presence of an external field." What do they mean, exactly, by "external field?" I know (or at least I think I...

(i) if \alpha=\sum_i \alpha_i(x) dx_i \in \Omega^1, \beta=\sum_j \beta_j(x) dx_j then\alpha \wedge \beta = \sum_{i,j} \alpha_i(x) \beta_j(x) dx_i \wdge dx_j \in \Omega^2 NOW THE STEP I DON'T FOLLOW - he jumps to this in the lecture notes: \alpha \wedge \beta = \sum_{i<j} (\alpha_i...

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http://img209.imageshack.us/img209/4922/14662031eo8.jpg

Can some kind person please explain why He-4 is so high and Li-6 is so low on the graph of binding energy per nucleon. Copy of the graph here http://en.wikipedia.org/wiki/File:Binding_energy_curve_-_common_isotopes.svg" It means that He-4 must be very stable right? Because binding energy is...

Can someone explain Charpit's Method to me (PDEs) ! Thanks

Homework Statement Initially the switch is closed in the circuit shown and the light bulb is shining brightly. What happens when the switch is opened? (diagram in attached link) 1. The bulb goes out immediately. 2. The bulb gets gradually brighter. 3. The bulb gets gradually dimmer...

I'm trying to study a proof for a quiz right now, and even though I have the answer, I don't get it because I don't understand what an orbit is. I got no definition in class, and can't find anything in the book. I looked on wikipedia, but that was completely over my head. Can someone please...

I am learning linear response theory right now and I have come across a mathematical technique I have seen before but I don't understand the reason for the application. What I am talking about is the insertion of the sum of basis vectors in the commutator. Generally speaking it looks similar to...

Why we are searching quantum gravity effect at the Planck scale? The question seems very stupid (and may be) but let me explain. I define a quantum object when his action is of the order of Planck constant \bar h. namely A~E \delta t~\bar h. So if i take a small amount of energy E i can take...

Homework Statement The reference frame K' moves in the positive direction of the x-axis of the frame K with a relative velocity V. Suppose that at the moment when the origins of coordinates O and O' coincide, the clock readings at these points are equal to zero in both frames. Find the...

Mechanics & physics,can anyone please explain the scenarios?Very practical Questions? Hi...Can anyone please be kind enough to help me? i know it will take a bit longer for u to answer. I have some scenarios and questions in the following pages...

I am reading a paper that uses a quantum mechanical notation that I do not understand. I have found a webpage that explains it, but I do not understand the explanation either: http://chsfpc5.chem.ncsu.edu/~franzen/CH ... (let Y represent the Psi) Specifically, I understand what <Yn|A|Yn>...

The problem comes down to this: At a gameshow there are three doors. Behind two of them there is a goat, and behind one is a car. You pick a door. The gameshow host, who knows where the car is, then opens one door that you didn't pick, but contains a goat. You are then allowed to change your...

Can anyone explain the physical meaning of "spin" in QM? I'm a physics master student and I've completed several quantum mechanics (or related) courses and i have no problem working with Pauli spin matrices, angular momentum L, spin momentum S and total momentum J for nuclear or atomic...

Can you explain to me... How Will Smith was "voted" (?) the top moneymaking movie star in 2008 by theater owners? http://www.usatoday.com/life/movies/news/2009-01-02-smith-top-moneymaker_N.htm He had two movies out, Hancock and Seven Pounds, which together grossed $267 million. But The Dark...

I wonder if quantum gravity effects can explain Inflation after the Big Bang? For example, in Loop Quantum Gravity, there are area and volume operators and eigenvalues, etc. Would there be jumps from one volume state to another with time? Thanks.

Hi, I was wondering what really ARE spectral lines? Are they electromagnetic waves? But still they are affected by magnetic & electric field in the Zeeman and Starks effect respectively, whereas the electromagnetic waves are not. so is there any theory explaining...

In an attempt to grow stronger (i'm quite feeble to be honest) I've decided to start doing dumbbell excercises. However, I'm quite curious - what actually causes muscle development? As in the process, what occurs in the body for it to occur, etc. Thanks in advance.

I've been trying to put this together in my head for a while and it doesn't come out. For example, if there are more stars on one half of the sky, does it mean that a thrown object will travel faster in that direction? If the object is at the edge of the universe, does it mean it will not be...

can anyone explain me about the bigbang singularity

was changed to a new thread... https://www.physicsforums.com/showthread.php?t=277401 thanks

I still need someone smart to explain 2 me momentum and Impulse throughly... 1. A hunter has rifle that can fire a.05 kg bullets with a speed of 900 m/s. A 40 kg leapord springs at him at 10 mm/s. How many bullets would the hunter need to stop the tiger dead in its tracks...

Explain differential equation of order 3? With example?

Can someone please explain how to compute this integral? This is not for school; I just came across it and I'm not sure what to do. Parts and various identities didn't help. \int x/tan(x) dx

Homework Statement A sphere completely submerged in water is tethered to the bottom with a string. The tension in the string is one-third the weight of the sphere. What is the density of the sphere Homework Equations Here is the solution to this problem. It is problem 15.17, the...

Can someone please explain the differences between: An Automorphism An Isomorphism A Homomorphism and An Endomorphism

I was reading a bit on thin lenses when a postulation was made that the image formed from the first surface would be the object for the second. The postulation made sense for when the first image is virtual, but I don't see how it works when the first image is real? Can anyone provide me the...

Homework Statement The approximate pH of a 1 M solution of NH4Br [Kb(NH3) = 1.8 x 10-5] is___ Homework Equations The Attempt at a Solution Ka(NH4) = 10^-14 / 1.8 x 10^-5 = =5.5555 x 10^-10 therefore, 5.5555 x 10^-10 = [NH3][H+]/[NH4+] Since 1 H+ forms for every NH3 that...

Homework Statement I'm trying to develop an expression for the maximum accerlation of a person pushing an object up a slope. I've figured out an expression for acceleration using F = MA based on the forces acting on the person and the object. Now I need to find the max accerlation. We...

Can someone explain to me how a false vacuum works? Thanks

I rendered this question accidentally during a discussion with a good friend of mine on the logical constraints that govern our interpretation of the world. The thought struck me as arcane initially, but after some consideration it is difficult to elicit and direct logical inconsistencies...

Can someone please explain to me the concept of vortex breakdown?

hello everyone. i want someone to explain general relativity step by step. please don't say that it is impossible.

Okay I don't know anything about physics and I'm trying to understand Heisenbergs (sry spelling) uncertainty principle, they say you can't measure the position and momentum at the same time (of an Electron let's say), I want to know WHY? I mean how does an electron move in the first place...

Can someone please explain to me what "Performance Factor" is? I wasn't sure where to post this, but as the title implies I need someone to explain to me what the concept of "performance factor" is. I'm not sure if that's the correct english phrase I'm looking for, but that's how my dictionary...

Greetings. I really want to know how to explain the . (i.e. in the unit N.m) to a person not expert to physics? As for the / (for example in the unit m/s) I can explain to one, that it is the rate or the value of the speed/velocity for every single unit of time, in this case second...

A plane weighing 220 kN (25 tons) lands on an aircraft carrier. The plane is moving horizontally at 62 m/s (139 mi/h) when its tailhook grabs hold of the arresting cables. The cables bring the plane to a stop in a distance of 88 m. (a) How much work is done on the plane by the arresting...