Confused Definition and 1000 Threads

Hi, I'm having some trouble with the Cabibbo matrix. I get vaguely what it's about but there are things I don't understand, and there seems to be so little information explaining about this out there. I know that before the top and bottom quarks were discovered, it was just a 2x2 matrix that...

So, I've been tasked to learn SUSY in a small time span (few weeks) and I've made some progress but I'm a little stumped on how deeply I should go into things while still making reasonable progress (get to phenomenology, etc). First of all, most primers seem to gloss over the algebra or go...

Hi, I'm from Canada and I'll be applying next year to Cambridge. Long story short, I'm a first year IB students and so far my first semester is predicted to look like this: French HL: 70 + English HL: 80 + Physics HL: 80+ Biology HL: 80+ Math HL: 90+ Chemistry HL: 70+ I haven't had such a...

I would be grateful if anyone could clear up my confusion with this relatively simple concept. It has been bugging me for 3 years now and I've never had a clear answer from my teachers. Consider a power line transmitting electricity: Power loss in the wire = I2R = VI To reduce power loss...

Homework Statement Hey I am confussed about how the Fourier trick works. In my book they have an example ...=integral from 0 to pie Pl(cos@)Pl'(cos@)sin(@) d@ then somehow they get ={0 if l' does not equal l and 2/2l+1 if l'=l Thanks Homework Equations The Attempt at a...

I'm reading Max Born's "Einstein's Theory of Relativity", 1962 version. On page 297 he says that a wire with a current in it is electrically neutral and surrounded by only a magnetic field. Yet on page 161 he says that current in a wire is the result of an electric field. It would seem that...

Homework Statement A cylindrical copper rod of length L and cross-sectional area A is re-formed to twice its original length with no change in volume. If the resistance between its ends was originally R, what is it now? Homework Equations R=p(L/A) The Attempt at a Solution Using...

Hi, I needed to write a function that takes a boolean vector and returns the position of the "1" values only. The correct way it was done was like this : function res = tmp(x) res=[ ]; for k=1:length(x) if x(k) res = [res,k]; end end I don't understand why the "if" statement...

vector momentum problem Homework Statement A car moving North at 9.0 m/s strikes a stationary car of equal mass. The first car moves off after the collision at an angle of 30 degrees West of North with a speed of 6.0 m/s. (a) What is the speed of the second car after the collision? (3...

Homework Statement Consider four vectors ~ F1, ~ F2, ~ F3, and ~ F4 with magnitudes F1 = 59 N, F2 = 29 N, F3 = 11 N, and F4 = 60 N, θ1 = 150 ◦, θ2 = −150 ◦, θ3 = 23◦, and θ4 = −56◦, measured from the positive x-axis with counterclockwise positive. What is the magnitude of the resultant...

Hello, I am trying to work out how you derive velocity in terms of spherical coordinates, could anyone point me in the direction of a simple and quite explicit derivation. I keep getting confused! Thanks.

Confused about this blueshift/redshift "paradox" Say you had a light probe with a sensor that converts light energy into electricity and and uses electricity generated to draft a chart of energy converted on paper. Now you send the probe on a 1 LY round trip. The probe has an internal drive...

Hi friends, I am a chemical engineering graduate from one of the reputed national institutes in India and presently working with a giant public sector unit of the govt.. I would like to pursue a degree on physics in the coming year can anyone guide me what all to prepare, how and where to apply...

Does traveling towards a light source at a significant fraction of c mean that you will infact see the light source sooner than say someone who is stationary at the point you began traveling at the fraction of c from? Say you are traveling towards a light source a light year away, will you see...

I know that generally complex numbers are represented in a two-dimensional plane with one real and one imaginary dimension. I also know that we have the quaternions, consisting of one real number and three imaginary numbers. The imaginary axis is always perpendicular to the real axis. The...

Homework Statement A ball is tossed from 1m above the ground to a total height of 12m. An unidentified object passes directly underneath it at 20m/s at a height of 1m. If the ball lands on the object as it passes underneath, how far away was the unidentified object when the ball was tossed...

Homework Statement http://img827.imageshack.us/img827/371/diagramv.th.jpg I'm supposed to determine the equivalent force-couple system at point A, but that's not actually what I'm posting about. I got the problem right except for the sign calculating the moment. The Attempt at a Solution...

1. In baseball, player throws ball so that the ball takes one bounce before it reaches infielder. Suppose that the angle at which a bounced ball leaves the ground is the same as the angle at which the outfielder launced it. The ball's speed after the bounce is half of what it was before...

Homework Statement See attachment I am confused by what they mean on part (a) are these sequences s_m and s_n the same sequence and this is what i should be showing?

hey, i am a little bit confused about the reactive power. we defined it as Q=UI sin(a) and the apparent power as S=UI Now I have to solve this excercise: Which percentage of heat loss in a power grid is caused by the reactive power, when the powerfactor is cos(a)=0,85? Now I...

My calc book rewrites this equation: |y|=e^c|x| As this: y=\pm e^cx But that doesn't really make any sense to me. I know I should understand why we're allowed to do that, but I don't. Could someone please try to explain it to me? I really appreciate your help, thanks!

Homework Statement For y'=1/(x+y), sketch a direction field and the solution through y(0)=0. Homework Equations I'm confused as to why there is a solution through y(0) - I thought that the existence theorem says that if y' is continuous in a box, then there are solutions through all...

Why should phase difference be small when resonance is small?

Homework Statement [PLAIN]http://img715.imageshack.us/img715/8128/66497284.jpg Homework Equations The Attempt at a Solution I'm really confused about this question and not sure what to do. I've only been able to find the angles and don't really know what to do next. I also think that it i...

We all know from time-independent perturbation theory that if we have an atom in ground state [0>, and when a time-independent perturbation acts on it, the energy of the ground state gets shifted and the ground state wave function also gets modified. Using Time-independent Schroedinger eq...

Homework Statement I'm confused about how to use KCL when doing Nodal Analysis. Please consider the diagram below: http://img27.imageshack.us/img27/4900/20091019131641633915550.jpg Homework Equations My first point of confusion is that the diagram shows the current "4Ix" going up...

Homework Statement i know that "A is necessary for B" means "B implies A". but i confused with the word "A is necessary of B" somebody help

Hello, if I understand correctly the Taylor approximation for a=0 gives me the possibility to approximate a function, say sin(x), at any x. But, what gives me Taylor polynomial at some point http://latex.codecogs.com/gif.latex?a\neq0 ,[/URL] what's the difference? what does it mean centred...

Homework Statement Suppose we have 2 insulated metal rods each measuring 40 cm. Now,the 2 metal rods are connected with 3 identical springs each of length 20 cm (force constant 2.0 N/m) in parallel. A current of 20A is passed through each metal rod in opposing directions. What is the extension...

let me start by saying that i love physics and i am very passionate about becoming an astrophysicist, but this semester i am taking my first e&m class and for the first time it my life i actually feel like i am confused (i might add that i am understanding it more than a majority my other...

Homework Statement We have to prove the speed of sound using a ultra-sound emitter, connected to EasySense software which records the speed for it to travel to surface and back. Known data - Speed of sound is 337 metres a second at 20 degrees celcius. Also, the distance covered is, 3.4m or...

Homework Statement Rank the atoms in electron affinity, from smallest to largest. Homework Equations none The Attempt at a Solution G has the highest energy, followed by H then K. I looked at the diagram and saw that- G= 1s^2 2s^1 (Li) H= 1s^1 (H) K= 1s^2...

Hello, I was reading Zeh's "The Physical Basis of the Direction of Time" but I just can't understand him in chapter 1 on something really easy: the definition of the phenomenological entropy + second law. Here is a screenshot I took from the googlebooks edition: Those two lines of...

:bugeye:Hi All... I am really confused about the mechanism of loss of energy when an EM wave hits a metal surface. I always thought the reflection was due to the motion of the electrons in the metal (due to the electric field of the wave). Which suggests that resistive losses would come...

Hi, I am having a hard time getting my head around the time slowing down bit of the theory, and I could do with someone explaining it to me. From my understanding, the faster you travel the slower time gets right? but also any frame of reference is valid, so speed is again relative. and...

Hey guys, I am totally lost in the idea why we have to change function in time domain to frequency domain to ease with our calculations. Let me break my question into serveral smaller ones. 1)What is the physical implication of transferring a signal to frequency domain? (I know that in...

Homework Statement A silo is under construction and a large brick is being hoisted up at a constant speed of 3.2m/s. The rope breaks when the brick is at a height of 28m above the ground. a) find the greatest height reached by the brick. Homework Equations i know which equation to...

Homework Statement You drive on Interstate 10 from San Antonio to Houston, half the time at 67 km/h and the other half at 112 km/h. On the way back you travel half the distance at 67 km/h and the other half at 112 km/h. What is your average speed (a) from San Antonio to Houston, (b) from...

Homework Statement Given: see attachment Five additional electrons are placed at the origin. What is the electric field now. Homework Equations Electric field equations of E=q/(4pi*Eo*r^2) The Attempt at a Solution I am wondering if the electric field would just be 50% higher...

Hi everyone. I'm having a bit of a crisis here and I'd appreciate any help. I'm 24 years old, I have a bachelor's degree in math, specializing in computer science and logic, and right now I'm doing a graduate diploma in engineering science at the University of Auckland. My grades in math...

Okay, I was doing some questions concerning linear law when I came across a question that asked me to convert a cubic equation into a 'linear equation' so that I can draw it on a graph. Cubic Equation: p(x+y-q) = qx3 Then, I convert the above equation into: y/x2 = (q/p)x However...

Hello, I am looking at scattering cross sections for neutrons. From basic scattering theory and the partial wave expansion I have understood that the reaction and scattering cross sections are dependant of each other. There can be scattering without reactions but only 1:1 the other way around...

hello ppl Imagine that you are on a spaceship flying very close to the speed of light and we know that time slows down significantly at this speed relative to that on earth. now say every day for the persons on the spaceship is a whole year for a person on earth. So for a person on the...

Hi all, The following is probably a very stupid question, but could anybody please tell me what they think? It has been bugging me for quite a while. I'm a bit confused about the probabilistic interpretation of Quantum Mechanics. I can't see how it necessarily follows from the experiments...

I'm not really a physics genius or professor so forgive my lack of knowledge. I was thinking about Einstein's theory of relativity earlier,then it just popped into my head doesn't that contradict The Law of Conservation of Charge?Ex:111grams of hydrogen = 10,000,000,000,000,000 Joules.but in...

i am confused about the double integral ʃʃ cos(x+2y)dA, where R = [0,pi]x[0,pi/2] i realize for the integral that i must do u-substitution. when i do this, however, do i also have to change the boundary conditions as in a single integral? i got -8 without changing the boundary conditions...

Confused about relativity? I have a question regarding the following explanation I have been given as below: If an astronaut were to travel at or near light speed to another star, there would be a difference in the time elapsed on Earth versues the time elapsed as perceived by the astronaut...

I have learned that the kinetic energy of a moving object is equal to its mass multiplied by it's velocity squared, divided by 2. If I takes off in my 2 million kg spaceship from rest to 1 million metres/second, I have calculated from this formula that I will need 1 million, million, million...

Static Problem...i am confused Homework Statement The Problem says " A rod is 5 ft long and its weight is 60 lb. one end of the rod is fastened to a vertical wall by a clip. other end is bound by a rop which is attached to point on the vertical wall situated at a 12 ft height from the clip...

I have always been confused about this. On here people constantly talk about traveling in a spaceship that goes .5c, or.9999c etc. But how can this be, no matter how fast one travels light will always travel at c compared to your reference frame. Does this not mean that no matter how fast you...