Origin Definition and 651 Threads

Homework Statement Let f(x,y) be defined : f(x,y) = 0 for all (x,y) unless x4 < y < x2 f(x,y) = 1 for all (x,y) where x4 < y < x2 Show that f(x,y) → 0 as (x,y) → 0 on any straight line through (0,0). Determine if lim f(x,y) exists as (x,y) → (0,0). Homework Equations Polar co - ordinates...

Homework Statement An overdamped oscillator with natural frequency w and damping coefficient g starts out at postion x0 > 0. What is the maximum initial speed towards the origin it can have without crossing the origin? Homework Equations x(t) for overdamped oscillator The Attempt at...

Homework Statement Assume that you have a configuration of conductors with varying electric potentials applied to each. You make the following measurements of the values of the electric potential at different points in a two dimensional grid: X = 0.0 cm Y = 0.0 cm V = 2.0 volts X = 2.0...

Homework Statement A point is uniformly distributed within the disk of radius 1. That is, its density is f(x,y) = C For 0 ≤ x2 + y2 ≤ 1 Find the probability that its distance from the origin is less than x, 0 ≤ x ≤ 1. [Note] My book says that the answer is supposed to be x2. 2. The attempt...

How did schroedinger arrive at the wave equation? I recently read in a book about the concept of wave packets using Fourier analysis and the wave equation was derived by forming a differential equation of the Fourier integral. But some books say that there is no formal proof of the...

Homework Statement A particle moves according to the position function x(t)=ct2+bt where c=3m/s2 and b=-7m/s. Find the velocity at the origin. 2. The attempt at a solution I tried just taking the derivative and setting t=0 to the equation as so: vx(t)=6t-7=6(0)-7=-7 m/s Although, when...

Homework Statement The first vibrational band in the absorption spectrum of H2CO is at 28871 cm-1. The first two bands in the emission spectrum (from v'=0 level) lie at 27021 cm-1 and 24687 cm-1. Explain these observations. Determine the band origin of the electronic transition and the...

Hi, I have the following question: Find the perpendicular distance from the origin to the plane x + 2y + 2z = 6. My solution is incorrect but I can't find what's wrong. I did this: I know that the distance will be a vector from the the origin to the plane, and it will be along a normal...

The advocators of Darwin’s theory of evolution discover that it is difficult for normal evolution rate alone to form the species diversity now. What factor(s) accelerated the origin of life and species diversity? Reference viewpoints: Novae, especially supernovae, would generate high energy...

Hi the first step to this is usually described as diffusion of electrons from the n type to the p type. However I have encountered sites and books that state that holes diffuse from p type to n type as well. I am of the opinion that only the electrons diffuse, and that there is no diffusion of...

Does anyone know why quantum states exist? In other words, is there an explanation for why the universe is built from discrete levels vs. some other system? I've scanned over numerous books on quantum mechanics and the history of quantum mechanics but I can never find a layman's answer to this...

By choosing among the following five options, what is the main source in the universe for the origin of the elements : silicon, lithium, bismuth, nickel and uranium? Primordial nucleosynthesis – fusion in core of low-mass stars – fusion in core of high-mass stars – slow neutron capture in...

By choosing among the following five options, what is the main source in the universe for the origin of the elements : silicon, lithium, bismuth, nickel and uranium? Primordial nucleosynthesis – fusion in core of low-mass stars – fusion in core of high-mass stars – slow neutron capture in...

On the Origin of Solar and Stellar Magnetic Fields There is recent evidence that the solar magnetic cycle has been interrupted. This is a link to Livingston and Penn’s paper that notes the magnetic field strength of newly formed sunspots is decreasingly linearly. Specifically, why the...

Given two 2D unit vectors (A and B) in different directions and positions in the same horizontal plane, is it possible to determine the origin (point of rotation) required to make vector B = vector A (same position and direction)? All this assuming that vector B is a rotated (only) version of...

I prefix this by saying I have never ever studied science nor was I even interested in it till after high school but the other day I had this thought. While we can maybe one day explain the universe. How will we ever explain the space its expanding into and how big is that space? This...

can we calculate the orgin of the big bang based on the wmap and drift of galaxies?

We know that the Higgs-particle gives an explanation as to why there is mass in the universe. But mass has another property/ability. It has the ability to resist change in its state of motion. Is this ability - inertia - explained by the discovery of the Higgs-particle? Does Higgs-particle...

Good evening. Can anyone explain me the origin of the electric field in the F-N-L's law ? I'm referring to this one : \int_l \vec E^* d\vec l =-\int_s \frac{\partial \vec B}{\partial t} d\vec S where \vec E^* is defined as (i'm reporting the words of the book) : \vec E - \vec v \times...

Homework Statement This problem is 2.95 of University Physics, 11th edition. Catching the Bus: A student is running at her top speed of 5.0 m/s to catch a bus, which is stopped at the bus stop. When the student is still 40.0 m from the bus, it starts to pull away, moving with a constant...

6/12 public lecture today by Nobelist David Gross at University of California, Santa Barbara: What's a fundamental theory of physics? http://www.fnal.gov/culture/NewArts/Lectures/11-12/gross.shtml Dr. David Gross received the Nobel Prize in Physics in 2004, along with H. David Politzer...

does the exchange coupling exists between atoms or between domains in magnetic substances?

Hi, I'm a physicist with a layman's interest in biology. I was just wondering what the physical requirements for the origin of life on Earth are expected to be. So, for example, pressure range, temperature range, chemicals needed etc. If this has an answer, how confident is the community, or...

Consider the graph of $${x^2 + 2 y^2 = 1}$$. What is the minimum distance of a point on the graph to the origin? When I calculated the point which has minimum distance from origin it came out to be (1,0) implying the min distance to be 1. The answer is 1/2. Help?

Homework Statement Calculate the angular momentum about the origin O=(0,0,0) of a particle of mass m moving along the following two trajectories: (a) x(t)=vt y(t)=b z(t)=0 (b) x(t)=Rcos(wt) y(t)= Rsin(wt) z(t)=vt Homework Equations L = r x p L = mvr The Attempt at a Solution...

Homework Statement Find the points x^2 + xy + y^2 = 2 that are closest to the origin.Homework Equations Distance FormulaThe Attempt at a Solution I have to first solve this without using Lagrange Multipliers. This is essentially an ellipse. So I first completed the square: 3/4\,{x}^{2}+...

Hi all, I asked Mathematica to evaluate a Meijer-G function for me, and it point blank refuses to. (See a related post in the Math and Science Software subforum...) I was wondering if anyone here could tell me anything about the behaviour of the function G^{7,0}_{0,7}\left( x\bigg |...

I have a C++ class for a math vector. I would like to add a function that rotates this vector in 3D, so that the user could input the direction of rotation as a norm vector, and the angle with which he would like to rotate, and have the function automatically rotate the initial vector for him...

I have a Plot using Frame, and AxesOrigin set to a convenient value. The plot process offsets the physical origin of the Frame so that the specified AxesOrigin is just inside the Frame border - ie there is an offset introduced for both axes. Is there a way to tell Mathematica not to set any...

In solving the two body problem we choose the center of mass of the system as the origin. But is the frame of reference we are setting up inertial? I don't think so. Suppose the central force is gravitation, A has mass 4kg and B has mass 1kg. If we put an object at the center of mass...

Homework Statement Hi everyone! I'm pretty good with multivariable limits, but this one has me stumped: Find the limit or show that it does not exist: \underset{\left(x,y,z\right)\rightarrow\left(1,-1,1\right)}{\lim}\frac{yz+xz+xy}{1+xyz} Homework Equations The Attempt at a Solution I could...

Dear Physicsforum, I have a rather simple question, which can probably also be solved with a rather simple answer. I am writing a paper on the history of the perception of time, on the scale of the big bang up until now. In this I use that nowadays the definition of 1 second is based on...

Homework Statement A ball of mass m fastened to a long rubber band is spun around so that the ball follows an elliptical path about the origin given by: r(t)=bcos(ωt)e(x)+2bsin(ωt)e(y) b, ω constants bold type indicates vectors Find the period of the balls motion. Homework...

Object moving towards or away from "origin" Homework Statement I just want to confirm that I got this right: Given a s(t) relation of an object. The object moves along a straight line. At some time t, s(t) will tell me if the object is to the left or to the right of the origin. If...

If a 1kg object is 1.5 m heigh. I find its PE to be 14.7 J. If it falls to the ground, the PE of 14.7 J goes to 0 as the object approaches the ground. Right? Now say the origin has been moved to 1.5 m where the object lies. Is the object at 0 J at the origin and approaching -14.7 J as it...

We know from classical mechanics that angular momentum L = r \times p depends on your choice of origin. My question is: How does this work quantum mechanically? We know we get certain eigenvalues, but does this apply only in a certain choice of origin? How do we calculate angular momentum at...

Homework Statement What point on the line y=3x-1 is closest to the origin? What is the distance to the origin from this point? Homework Equations The Attempt at a Solution OK, I thought I knew how to do this but I don't think my answer seems right. I find the normal vector...

I am doing a Michelson interferometer lab which instructs me to use the equation Fb=(Fl*v)/c, where Fb is the beat frequency, Fl is the frequency of the laser, and v is the velocity of a oscillating mirror. The interferometer has one stationary mirror and a mirror that is mounted on a speaker...

Hi, What do you think of this thought experiment that demonstates a situation where the origin of inertia must be gravitational (Mach's Principle)? Imagine an empty box with perfect mirrors on its walls. Now let us pump in a large amount of photons into the box. Let us assume that...

Homework Statement Let's say the sphere has a radius of 3 and is centred at (3, 0, 3). Is there a way to implement spherical cooridnates, or is it essentially impossible for this situation to not get messy? I have searched everywhere as to how I can evaluate this, but to no avail. Any help is...

Hi, I'm interested in what people think of Dennis Sciama's 1953 paper on the origin of inertia in which he shows how Mach's principle could work using a simple argument with Maxwell-type gravitational field equations...

Hello, I've seen spin orbit coupling being explained by going to the rest frame of the electron and noting that the proton is then a moving charge and hence has a magnetic field, which interacts with the spin of the electron, effectively coupling the spin and angular momentum of the electron...

[b]1. Consider three charges q1 = 4.3 nC, q2 = 6.6 nC, and q3 = -2.3 nC, arranged in a triangle as shown below. (a) What is the electric force acting on the charge at the origin? N, ° counterclockwise from the negative x-axis (b) What is the net electric field at the position of the...

reference in "the origin of species" I've been reading Darwin's "The Origin of Species". It turns out the benefit isn't so much seeing a familiar theory in original form, although there is a fascination in seeing evolution described without knowing Mendellian inheritance. The best benefit is...

New thoughts during my second read of "The Origin of Species"... On humans. Every time I read this book I have new ideas and this one came to me after a second read of Darwin, and another look into the documentary "Homo Futurus". For those of you who have not seen this documentary...

Homework Statement Find a > 0 such that the tangent line to the graph of f(x) = x^{2}e^{-x} at x = a passes through the origin. Homework Equations The Attempt at a Solution First I found the derivative to be: -e^{-x}(x-2)x , which is the slope of the function. I know the tangent line...

The aerial view of Valles Marineras has a strangely familiar look to it. As a kid I would shoot BB's at all sort of fruit and mud and stuff. Sometimes I'd hit a rotten apple or tomatoe with a glancing shot that would rip open a gaping tear for a distance as the BB would enter, force material out...

I have a problem that I've been unable to find a simple solution for. When solving Schroedinger's equation for a central force, the nonradial part of the solution can be found with spherical harmonics, but the radial part is much more difficult. E\psi = -...

Hello! I'm looking for information, articles and theories about which could have been the original molecule of life: DNA, RNA or protein. Most of what I've found is based on the RNA world theory (which I think is pretty well explained and sounds plausible), but I haven't found out any...

I have to say a lot of the physics discussd in this section is a little beyond me but that does not stop me thinking. Given the search for the Higgs Boson which allows mass to exist it has occurred to me what is the origin of the electric charge. Surely as mass is property with an origin what...