Origin Definition and 668 Threads

Ok, there are a couple of other threads about this, but they don't seem to answer my question. If I take the double derivative of 1/r, I'll get 2/r^3, but if I take the laplacian, I get something different. Why? Namely: \frac{d}{dr}\frac{d}{dr}(\frac{1}{r}) = \frac{d}{dr}...

Homework Statement Calculating the horizontal component of an electric field at the origin of a semi circle. The image link is: http://imgur.com/SXYs4Rp The Attempt at a Solution I've tried using the formula k∏(Q)/r (8.98755*10^9)∏(-7.85*10^-6) / .113 = -1.961 * 10^6. Can anyone see...

The line L passes through the origin and is parallel to the vector 2i + 3j. Write down a vector equation for L. r=(0,0)+s(2,3) my question pending this is correct, could this be written as: L=s(2,3):confused:

I was reading a Utility Guidelines document (Yale, for internal systems, but publically available) and came across an interesting clause: No piping, fittings, or specialties manufactured, fabricated, and/or assembled in China, Taiwan, or India are permitted on any project including those...

Greetings helpful gentlemen and gentle women! The following is a problem I ran into during my internship. The background of my problem is biological/chemical in nature, so I’ll try to bother you as little as possible with the details. Thanks in advance for any help given. Homework...

Hello, everyone! I have some education problems about how to teach(or share?) child the origin of science. By the way, I'm Taiwanese so my English talking ability may not be good... I've studied so many physics educational theses, history of physics and philosophy..and realize the importance...

I want to transform from rectangular coordinates ( xyz) to (x",y",z") rectangular coordinates that is rotated at the origin as show in the attachment. Then I want to transform (x",y",z") rectangular coordinates into Spherical coordinates. Attach is the method I use, I want to verify I am doing...

Hi all, When an object is heated , why is the amount of change in its length directly proportional to the original length ? I have read that the increase in length it is directly proportional to the initial length in most of the articles. But I wanted to know how this proportionality arrived...

As per current theory's we know that time did begin with the big bang, what before then and does big bang highlight the explosion or the dense ball which was everything (universe.)

I was just curious. I have a program that asks for input file name and output name when the console is executed. I needed to run it and automatically pass these file names. I found a way.. test.exe <files.tmp where files.tmp has 2 lines. First line is name of input file, second is output...

einstein explained the origin of gravitational force from the concept of space time curvature.but what about the electrostatic force...does it also originate from some sort of curvature.please explain...

I have been following Quantum Cosmology since Hawking's A Brief history of Time first appeared. That inspired me to attempt to drill down to the technical papers involved. I also made use of the book by Hawking and Penrose, The Nature of Space and Time. Very broadly speaking there seems to be...

"Quantum Optics," by Scully and Zubairy, attempts to explain the natural line width of an emitting atomic ensemble (in a resonant cavity with leakage) using random spontaneous emission events of the atoms (which in turn is due to interactions with the vacuum field). The basic idea and...

Homework Statement Say you have an equation of a line in 3 space and you want to find the distance from the line to the origin how do you go about it? I guess by definition the distance of a line to a point ( say the origin in this case) is the minimum distance such that the line and...

correct me if I am wrong but there are fundamental fields that are responsible for the forces and properties. A) how do these fields (em, higgs ect.) influence matter? B) where did they come from and when? Thanks

Homework Statement Hey All, I'm hoping that you might be able to help me understand where the wave number "k" referred to in equations 6.62a and b below comes from. It makes sense to me that IF k=(2mE/hbar2) normally, that 6.62b would have E-V instead of E. That this change is made makes...

Question: Particle A is resting on the origin. Particle B travels along the path of f(x)=-cos(x-7)+3. What is the minimum distance that the particles can be apart? Attempt: I tried to find the minimum of f(x)=-cos(x-7)+3. So I found when the derivative is 0: dy/dx= sin(x-7)...

Ive repeatedly asked people and my teachers how to solve logs by hand, and I've always got the same answer "They used tables and/or taylor series" but when i ask how the tables were made no one seems to know. So i am curious as to how John Napier and other mathematicians at the time found the...

Thanks again to those who participated in last week's POTW! Here's this week's problem! ----- Problem: A point is uniformly distributed within the disk of radius 1. That is, its density is\[f(x,y)=C,\qquad 0\leq x^2+y^2\leq 1\] Find the probability that its distance from the origin is less...

In my reading about Astronomy, I have encountered two seemingly different scenarios for the origin of the Moon: (A) Planet Gaia (unsure of spelling) crashed into the Earth. It nearly destroyed the Earth, but from that collision, debris formed into the Moon. (B) Planet Orpheus crashed into...

I'm trying to find information on the origin of parametric equations. Such as who developed them, and around what time. Unfortunately I can't seem to find any information, beyond the basics of what parametric equations are. I was hoping someone here might be able to point me in the right...

Find the ellipse centered at the origin that runs through the points (1,2), (2,2), and (3, I). Write your equation in the form $$ ax^2 + bxy + cy^2 = 1 $$ I understand the $$ ax^2 $$ and $$ cy^2 $$ in the equation because the equation of an ellipse centered at origin is $$ (x/a)^2 + (y/b)^2 = 1...

Hello, I hope somebody can help me with this one. Homework Statement I want to find the integral of 1/x^N*exp(ix) from -inf to inf. Homework Equations It is very likely that this can somehow be solved by using Cauchy's integral formula. The Attempt at a Solution I tried to...

Hello, If a rectangular waveguide (or square well, etc) is centered at x=a/2, y=b/2, solution (e.g. for TE mode) is: H = Ho Cos(m*pi*x/a) * Cos(n*pi*y/b) (n,m = 0,1,2,...) So for TEn=0,m=1, H = Ho Cos(pi*x/a). If it is centered at the origin, you get even and odd solutions: H = Ho...

What do you think of the article published in the "European Physical Journal D" with the title: "The quantum vacuum as the origin of the speed of light" ? http://link.springer.com/article/10.1140%2Fepjd%2Fe2013-30578-7

1. A submerged scuba diver hears the sound of a boat horn directly above her on the surface of the lake. At the same time, a friend on dry land 22.0 m from the boat also hears the horn (Figure 1). The horn is 1.2 m above the surface of the water. What is the distance (labelled by"?" in Figure 1)...

Transmission line equation is of the form- Φ(x, t) = F(x − ct) + G(x + ct) where F(x-ct) is the forward traveling wave and G(x+ct) is the reverse traveling wave 'x' is the distance from the origin. Now my question is where does the origin lie? Usually in Transmission lines we assume...

Homework Statement You have the simple harmonic equation for a transverse wave which is y(x,t)=Acos(10∏t+5x), what is the wave function at the originThe Attempt at a Solution By "at the origin" does it mean where x=0 and t=0. Because it that case y=Acos0 and therefore y=A. Is that right?

It's common to express phase differences between two sinusoidal waveforms as a "phase angle", with a full cycle corresponding to 360 degrees. What is the origin of this nomenclature, and why is phase expressed in degrees? Examined naively, the time domain representation of two waveforms...

Homework Statement a. Determine the complex potential for two equal counter-rotating vortices with strength \Gamma, the positive one located at z=-a and the negative one at z=a. b/ Show the shape of the streamlines for this case. Homework Equations z = x + iy = r*e^(i\theta) W(z)...

Homework Statement Consider three charges in a triangle as shown. 1. What is the net electric force on the charge at the origin? 2. What is the direction of this force(between -180 and 180)? 3. What is the magnitude of the net electric field at the position of the charge at the...

In a general situation, how do you change origin (mathematically speaking) in a physical context i.e. with position vectors, constant vectors, unit vectors to certain directions ... ? I am a bit confused with the concept.

I'm trying to understand the origin of thermal radiation. All things with a temperature emit electromagnetic radiation. Every discussion I've found starts with that as a premise and then goes on to Wien's displacement law and Planck's law, etc which I follow. But *why* do all things...

Homework Statement Let a system of forces (F1,...Fn) act on a body at points (x1,...xn) respectively. Assume that the resultant or net force vanishes (sum of forces = 0) Show that the resultant torque of this system is independent of the choice of origin, i.e. for 2 different origins x0...

1. +3.00μC point charge is at x=1.00cm and y=.750cm. -2.50nC point charge is at x=0 and y=-5.00mm. What will be the acceleration of an electron (Me=9.109X10^-31 kg) when it is at the origin (only force acting on the electron is the Coulomb force)? 2. K=8.988X10^9 N(m^2/c^2) Fc= K(qs...

Hello, Could someone describe the origin of the equation c2=1/ε0μ0 Is it derived from fundamental reasons? Thanks.

hi, i m new to this forum,this is my first post,i have recently started studying heat transfer. i m am little bit confused about the origin of thermal radiation in human beings.i mean radiations are emitted when an electron jump from a shell/orbit which is far from the nucleus to a shell which...

Hi all, Suppose we find the first cause that created the universe. What about the origin of this very first cause? Suppose it is X. What about the origin of X? Suppose it is Y. What about Y? And so on... Can we ever find the origin of this universe?

What is the origin of inertia? This is a question asked by many people. I believe even Einstein pondered on this and did put some of his thoughts in a paper, but nothing really conclusive. In Newtonian gravity, inertia appears to be just something that is inherent to mass. However, given...

Homework Statement Find a plane through the origin that meets the plane M : 2x + 3y + z = 12 in a right angle. How do you know your plane is perpendicular to M? Homework Equations Honestly have no idea... I know how to find an equation for a plane given a normal and a point, however...

Recently, in the Scientific American blog http://blogs.scientificamerican.com/observations/2012/11/29/person-of-the-year-nomination-for-higgs-boson-riddled-with-errors/?WT_mc_id=SA_CAT_physics_20121130 the author criticizes Time Magazine for its science reporting, which of course is nothing...

Suppose you have a particle in one dimension in an energy eigenstate, i.e. Hψ(x)=Eψ(x) for some E. For an observer B in a coordinate frame with the origin translated some distance K to the right, the wavefunction of the particle looks like ψ'(x) = ψ(x+K). Surely, we expect the energy that B...

Hi, I've been reading that in a relatively normal environment about 1/2 of human heat loss is due to radiation. Most of this seems to have a wavelength of 10-12 μm. Could someone here speak to the molecular origin of this? I'm guessing it is mostly from water molecules going from a higher...

I always see the example f(x,y)={xy/(x2+y2) if (x,y) =/= (0,0) and 0 if (x,y)=(0,0)} given as the example of a function where the partial derivatives exist at the origin but are not continuous there. I have a difficult time wrapping my head around this and was hoping someone could...

Homework Statement A 1.4 kg object at x = 2.00 m, y = 3.10 m moves at 4.9 m/s at an angle 45° north of east. Calculate the magnitude of the object's angular momentum about the origin. Answer is 5.3 kg m^2 /s Homework Equations These were the only three I could think of: L=Iω L=mvr ω=v/r The...

The C and P symmetry violations are deduced from the separating the right-handed representation from left-handed representation in electroweak model(Weinberg theory).Then I do not understand why we can consider the left-handed fermions living in a representation separating with that of...

An object is launched from the origin with a velocity of 20 m/s at an angle of 30 degrees above the x axis. The object lands on a roof that is 4 meters high. What is the time when the object hits the roof? a) 1.11 s b) 1.27 s c) 1.33 s d) 1.49 s e) 1.67 s I did 20 (sin(30)) = 10 m/s...

Dear Forum, I would like to understand what the origin of spin 1/2 is. I read in Feynman's lectures that the origin is related to quantum field theory. I know nothing about quantum field theory. Is there an easy explanation? Thanks Cabrera

Will anyone help me to understand the concept of reduced mass , where does it come from and its physical significance

Homework Statement Any help on this would be immensely appreciated! I am having trouble interpreting what my instructor is trying to say. Consider a simple linear regression model: y_i = \beta_0 + \beta_1x_i + u (a) In regression through the origin, the intercept is assumed to be equal to...