Explain Definition and 1000 Threads

What am I doing wrong in this problem? Please explain to me what I am doing wrong. Thanks h-bar is plank's constant. E = (l(l+1)(h-bar^2))/2I (l = 1) I = Mh*R^2 Mh = 1.67x10^(-24)g R = 161x10^(-10) cm For I i got 4.33x10^-40 So when i plugged in I for the top...

For finding series expansion solution of problems like f(x) = h(x) for 0<x<1 f(x) = 0 for 1<x<2 0<x<2 Where the Fourier series expansion only integrate from x=0 to x=1 only and totally ignor the portion of x=1 to x=2. This is also true for Fourier bessel series expansion...

Can't we simply assume that the initial condition for the universe is perfectly spherically symmetric, and the problem is solved? In other words, can't we make the CMB homogeneous just by imposing homogeneous initial conditions? The fluctuations can be explained by quantum effects. Of course...

If you had 3 sentences to describe special relativity to someone that doesn't know anything about it and 3 sentences to describe general relativity, how would you describe it? I'm reading Fabric of the Cosmos and trying to get a grip on these theories, just a basic grip, I probably won't...

I'm trying to make a soda can roll on its own down a level hallway and someone gave me this explanation on a possible way to do it, but I'm having trouble understanding how to execute it. Can someone explain it in different words? [FONT="Arial Narrow"]"One complicated mechanical way is to put...

Being possibly the newest member here, I would like to put a question that has troubled my mind for quite a while.. If I have a uniform ring (having a certain mass) and a point mass in some idealised gravity free space & I orient them such that the point mass lies exactly at center of the...

C# vs c ! Hello every body! can anyone explain what this c# code does or give a C equalivent? public static void Replace(ref byte b, int pos, byte value) { b = (byte) (value == 1 ? b | (1 << pos) : b & ~(1 << pos)); } public static byte...

I'm studying for my Quantum Mechanics course and I've understood most of it so far, until we reached the quantum harmonic oscillator. Finding the solution was no easy feat and I have to say I only had a slender grasp of the derivation, but now I'm being given questions about certain energy...

I don't understand how matter can be transformed to light and light can be transformed into matter? Also, how exactly does this happen when something happens to one particle and something equivalent happens to another particle of the same type on the other end of the Earth instantaneously...

In doing math I try not to memorize shortcuts/simplifications, but instead understand what's happening. When studying integrals, my professor gave out a few "simplifications" for us to use on problems; most of which I have been able to figure out, except one. I just cannot seem to figure out the...

Two blocks placed one on top of the other are lying on a horizontal smooth surface. The coefficient of friction between the blocks is \mu. Case 1: Horizontal force F is applied to the lower block (Fig. 14). [PLAIN]http://www.monbattle.com/1.jpg Please help me to find out how they have...

Can someone explain to me what renormalization is? And why General Relativity isn't renormalizable?

It has been told to me that atmosphere exert a pressure (known as atmospheric pressure) on the surface (I'll take water surface here). And as we go down into water (any fluid, but for instance I'm taking water) the pressure increases. And this increase in the pressure is independent of the shape...

Hello. In Arfken(6rd edi.), p.104 around eqn(2.3), ~~In general, these unit vectors will depend on the position in space. Then a vector may be written, V=\hat {q_{1}}V_{1}+ \hat q_{2} V_{2}+ \hat q_{3} V_{3} \underline{\mbox{but the coordinate or position vector is different in...

Hi, please, help me understand this circuit that is drawn here: http://wild-bohemian.com/electronics/flasher.html I have learned about miltivibrators (which is what I believe this is) in my electronics classes but never really understood them. I tried understanding it myself - as the...

I am currently reading books explaining both classical and modern physics, such as stephen hawking, brian greene, and enjoy learning from these books. However i would love to learn more about the mathematical equations and formulae behind these theories. Does anyone know a book that...

Homework Statement Could anyone explain that I got two different answers for this question: find dy/dx of \frac{x}{x+y}-\frac{y}{x}=4 Homework Equations The Attempt at a Solution 1. using quotient rule: \frac{x+y-(1+dy/dx)x}{(x+y)^{2}}-\frac{x\frac{dy}{dx}-y}{x^{2}}=0...

Homework Statement I should know this, but I'm using it as a step in one of my proofs and having trouble explaining how it works. Can someone help? -sin2x - cos2x = -1 Homework Equations The Attempt at a Solution Not sure how to prove and explain it. And sorry about the title gents I'm using...

LRC circuit , please explain this .. what are the Resistive Element, Inductive Element and Capacitive element of LRC circuit please explain

Say you have an equation like this. Xcos17 + Xsin17 = 600 If I want to solve for X, I know that I can divide by cos17 + sin17. So it ends up being X = 600/(cos17 + sin17). However, why is it that it becomes just one X on the left side? There are two X's and dividing by cos17 + sin17...

So I don't understand what all the craze is about entropic forces because as far as I can tell, they're nothing new. All forces as we understand them are caused by a large number of particles. The electric force is due to the interactions of large numbers of photons; the weak force due to...

Homework Statement Two blocks connected by a string are pulled across a horizontal frictionless surface by a horizontal force of magnitude F=14.0 N. What is the tension (T) in the connecting string? so you have block 1 (mass of 2kg) then the string then block 2 (mass of 5kg) then the force...

Can anyone explain "dispersion" to me in simple words? Can anyone explain "dispersion" to me in simple words? like,, when waves escape from a small gap why would they s[read out in circles? thnx for help!

Hi guys. Firstly, sorry if this question is far to easy for this section of the forums. Basically, I was bored and decided to take apart a microphone I that I had just lying around. It came with a box that you have to put the microphone through, which had the following circuit in it...

I have heard about people bow hunting whitetail deer where a perfectly placed shot can turn into a complete miss due to the deer's reaction. When I heard this, I thought it was impossible. But I found a clip on the internet showing a step by step shot missing a deer. Here's my basic thinking-...

Phew, I made the mistake of posting these questions on Yahoo Answers and got blown away by people who wanted to convert me to Christianity. I had forgotten about this forum. Thank goodness it's here. So it's actually two questions: #1: Intersex I've just discovered some literature on intersex...

Say I have two 3d vector functions A and B I would intuitively think that the xhat component of (A dot Nabla)B would be (dAx/dx+dAy/dy+dAz/dz)Bx but my book gives it as Ax*dBx/dx + Ay*dBx/dy + Az*dBx/dz why is this so? why isn't A dot nabla equal to (dAx/dx+dAy/dy+dAz/dz)? My...

can you please explain why this (TLsin30.0° − w((L/ 2)cos30.0°) − w(Lcos30.0°) = 0) becomes this T sin30.0° − (3w/ 2)cos30.0° = 0 i though i can do all the transpose and other stuff. but i can't figure that one. i want to get the T. please help me.

can anyone explain what actually surface tension is?? I am confused about surface tension. Everywhere it is written that due to unbalance of forces at surface the molecules at boundary tend to move inwards and thus surface tends to take minimum area as possible. This is ok but it is also...

I was looking on amazon.com and looking at Leonard susskind's black hole war and David Griffith's Introduction to quantum mechanics and they were both hard cover and Leonard susskind's book contained more pages than Griffith's Introduction to Quantume mechanics costs 5 times as much as Susskind...

Homework Statement A 0.46 m long guitar string, of cross-sectional area 1.1 10-6 m2, has Young's modulus Y = 2.20 109 N/m2. By how much must you stretch the string to obtain a tension of 10 N? Homework Equations ? The Attempt at a Solution I don't know how to begin this...

Does time "stopping" at c explain spooky action at a distance? My thinking is this: We know that two interacting photons will adjust their spins relative to each other. We know that if one of these photons change their spin at some time in the 'future', the other photon will instantaneously...

Homework Statement A small boat is floating in a swimming pool. The boat contains a heavy rock. If the rock is tossed out of the boat into the pool and the rock sinks, what happens to the water level in the pool? What if the rock floats? What if the rock became submerged in water (but didn't...

Special theory of relativity says that in the absence of an absolute reference, different observers may disagree on the time at which a particular event happened. With this knowledge, how do i explain time travelling? Every observer should be witnessing the same set of events (though their...

Explain Why we get hurt by kicking a brick Homework Statement You can easily move a brick lying on a floor by gently pushing it by your foot. But you hurt your foot when you try to kick the brick. Explain why? (in 60 to 80 words) Homework EquationsTheory Question The Attempt at a...

I'm good in writing functions in Matlab , however since moving to Mathematica , I find it pretty hard to write them . For instance I need to write a function that returns a [1,0,-1] to integers, meaning x>0 , x==0 , x<0 with a single If , but I didn't find a way with one (only two)...

from wikipedia for "The most general equation for rotation of a rigid body in three dimensions about an arbitrary origin O with axes x, y, z is"... i thought that the sum of the torques on a system is just equal to d/dt(L)=d/dt(Iw)...apparently not - but i can't understand the notation...

Hi.I have got this circuit for a low cost short range FM transmitter but I am unable to understand the working and functionality of the circuit.Please help me in understanding the working.What I know is that its working as a VCO(voltage controlled oscillator) when input (through electret mic) is...

What is inflation (in big bang theory not economics)?

Can someone please explain to me how to do combinations?

Here I propose a VERY SIMPLE and intuitive argument that MWI, with its MINIMAL set of assumptions, cannot explain the Born rule. The argument goes: The minimal set of assumptions defining MWI is: 1. Psi is a solution of a linear deterministic equation. 2. Psi represents an objectively real...

Homework Statement I have to find the measures of the angles x & y. Homework Equations Sine Law Cosine Law The Attempt at a Solution First thing I tried to do was find the measure of the angle @ A. a/SinA = c/SinC 66/SinA = 25/Sin10.5 and then I end up with 28...

Homework Statement What characteristics of a sound (such as frequency and wavelength) change for the speed of sound to change in each medium? Why do these characteristics change? For example: Why does the pitch of sound produced by pouring water into a tube increase as more water is poured in...

I thought it is (e^x)^2 with u = e^x so it should be u^2 but he get only u without a square. Can anyone here explain it. The red box. http://img6.imageshack.us/img6/3272/whatj.png

F=-\nablaV i cannot fully understand it ,though i can deduce it in some ways. i also want to know why potential energy is so extensive and important.

Mtd2 spotted this paper by Steven Weinberg that just went on arxiv. http://arxiv.org/abs/0911.3165 Asymptotically Safe Inflation Steven Weinberg 13 pages (Submitted on 16 Nov 2009) "Inflation is studied in the context of asymptotically safe theories of gravitation. It is found to be possible...

Explain the difference for each of the following pairs of actions in terms of impulses; (a) A golfer's long drive and a short chip shot; (b) a boxer's jab and a knock-out punches; (c) a baseball player's bunting action and a homerun swing

How do you explain this?

can explain to me what is mean of span? from book, it say "every vector in the space can be expressed as linear combination of the vectors, then it called the span of vector." but i still can't catch its meaning and concept.

Okay this isn't really a problem, but I want it explained too me instead of the books way. We are doing a section on mechanical energy, and for the entire course with vectors, force, etc, we have always used rcostheta and rsintheto to find an x and y force. Now tell me why we do this? Is...