Origin Definition and 651 Threads

Hi Homework Statement I'm trying to follow and work through a derivation in my textbook, making sure I can replicate the steps myself and understand what's happening. However, I came across this approximation and can't seem to figure out where it comes from or why and the book gives no...

Homework Statement Find the transformation matrix R that describes a rotation by 120 about an axis from the origin through the point (1,1,1). The rotation is clockwise as you look down the axis toward the origin. Homework Equations Rotations about the z-axis are given by R_{z}(\alpha) =...

I am curious as to what is the true nature of the atom and how far we can extrapolate backwards as to its primal cause. Are atoms caused by subatomic forces, or energy? Or are the terms 'Force' and 'Energy' metaphors for processes science does not fully understand yet. If we are able to answer...

I have a point in 3d space at (x, y, z) with a rotation of (i, j, k) based from the origin (0, 0, 0) with a rotation of (0, 0, 0). What I would like to do is move the origin to a new position and rotation and have the point rotated with it. What series of calculations and manipulations need to...

Hi, I'm doing a IB Physics internal assessment on how the length of a tube of playdoh in a straw relates to the resistance of that tube. I tested it by connecting a 150 ohm resistor to one end of the tube of playdoh and connected the two to a power supply. My data at the different lengths all...

I would be most gratified if someone learned in Physics would explain Physicists' point of view on the question of the Universe's origin in the following philosophical context: It seems to me that to avoid infinite regress it is necessary at some point in the causal chain to posit...

Is precession caused by uneven mass distribution in the gyroscope, or by an uneven supporting surface, causing a couple to form (i.e., normal force and gravitation force start to have non-zero cross products)? Is precession analogous to circular motion, the angular momentum vector is having its...

1. Homework Statement find the points on the surface z^2=xy+4 closest to the origin i tried the distance formula but it got too messy, i think there's an approach using lagrange multiplier but i just can't quiet figure it out...?

where or how did language come from ,ive been thinking about this for a long time i think it may have evolved ,very slowly like this maby many thousands of years ago a leader or head of a tribe might have used words or noises or grunts close to what we now know to get the attention of his tribe...

Some of galalxies have bar style center. Very mysterious. The origin? The galaxies are SBa, SBb and SBc style. Spiral galaxies are familiar to us. it seems like hurricane. What kinds of force act on bar centered galaxies?

Let T1 be the reflection about the line 2x−3y=0 and T2 be the reflection about the line 2x+5y=0 in the euclidean plane. - first I was asked to find the T1°T2 matrix. I did that. - now I need to find the counterclockwise rotation about the origin of T1°T2 I should use...

we all know the cosmic rays comes from outer surface of the Earth from higher altitudes and enter the Earth's atmosphere in all directions. but experimental studies have revealed that intensity of cosmic rays increases with altitude and reaches a maximum at about 20 km above Earth surface and...

You're traveling at 25m/s when you notice something ahead. you apply the brakes and come to a stop in 4 seconds. construct a x vs.t graph, a v vs. t graph, and an a vs. t graph for the 4 sec time interval if i could get what the position vs time graph looks like, i could get the rest. At first i...

Hi, I've been reading about particle- and quantum physics and have seen some educational video's about it. But I do have a probably philosophical question about it. Most likely based on ignorance (but what question isn't) and false interpretations of what I think to know. This is what I...

If I "create" a stream of photons in the lab or if I spectographically select a stream of photons from a star, I get the same experimental result in a double slit experiment? In other words there is no difference between photons whose point of origin can be deduced to be eons ago vs those...

I was wondering if anyone is familiar with D.W. Sciama's theory of inertia based on Mach's principle? I came across the theory in a book or selected writings on motion I found at a used book sale and found it very compelling. Just curious to hear any fallacies in his reasoning or negative...

Homework Statement To get used to finding the center of mass of an object, I have decided to start with a uniform density square. The square is centered at the origin. The center of mass should be at the center of the square, and thus at the origin. When I tried to solve this however, my...

Homework Statement A soccer ball is kicked at 25 m/s at an angle of 22 degrees . The ball hits the crossbar 2.5 m off the ground. Where was it kicked from? Homework Equations d = ViT + .5* a * T^2 The Attempt at a Solution I have no clue

Homework Statement A 3.2 kg particle moves along the direction under the influence of a force described by the potential energy function U = a k~xk, where a = 5.48 J/m and x is the position of the particle in meters measured from the origin as in Figure. The total energy of the particle...

Homework Statement What must hold true for a function to have a tangent at the origin. Eg. Given f(x) = 0, x = 0 and f(x0 = xsin (1/x) x does not equal 0 will the graph have a tangent at the origin? Homework Equations The Attempt at a Solution

1. Is it possible that dark energy didnt originate from bigbang but from another that precedes the bigbang? 2. Are dark energy and dark matter in our solar system? Thank you very much

Does anyone know a resource (book, website, etc.) where the origin of notations in physics is described? For instance it is clear that F comes from force, but it is not clear why c is the speed of light. I would like to find out how did people come up with the existing notations for physical...

Hi, I'm a physics student but I have not done much astronomy/cosmology. I was sitting here thinking, and something struck me. This thought is only a couple of minutes old so it's not much more than half-arsed musings at this stage. However, I am curious about whether someone who knows what they...

Why does a vector space need to go through the origin? I am not sure I understand the geometric importance of that, or the importance of it as it pertains to the axioms of a vector space. Is this to say I want any vector in the vector space to lie completely in the space, as oppose to say...

Suppose that some time in the future a clever group of theorists and experimentalists finally devise a way to accurately determine the value of the Hubble Constant. Say by an interferometer connected to a quantum computer. Everything works fine in the lab and is checked and checked...

Question: A Particle of mass m can slide freely along a straight wire placed in the x-y plane whose perpendicular distance to the origin O is h. Denote the projection of O on the wire by on the wire by C. The line OC rotates around the origin (in the x-y plane) at a constant angular velocity...

I have read many arguments concerning the issue of the famed “Twin Clock Paradox”. Very many arguments go through considerably complex explanations so as to defend Special Relativity or dispute it. But the explanation is actually much simpler. In every proposed twins paradox, there is a Frame...

Homework Statement Eight 3.0 μC charges are located at the corners of a unit cube centered about the origin with 1mm edges. How much work does it take to bring a 5.0 μC charge from infinity to the origin? Homework Equations U= k*q1*q2/r The Attempt at a Solution r=...

Electrodynamics force is f_i=F_{ik}j^k=F_{ik}\partial_j F^{jk}. I claim that the only way to obtain the Maxwell energy-momentum tensor T_i^j=-F_{ik}F^{jk}+\delta_i^jF_{kl}F^{kl}/4 is to write the force as a divergence: f_i=-\partial_jT_i^j.

I have started to learn BCS theory and I am not been able to find a derivation of the effective attractive electron-electron interaction which is assumed to explain the Cooper pairing. Can anyone point me to a reference where I can find this derivation? Jan.

Homework Statement Three charges are fixed in the x-y plane as follows: 1.6nC at the origin (0, 0); 2.6nC at (0.55 , 0); –2.1 nC at (0, 1.15 ). Find the force acting on the charge at the origin. Express your answers using two significant figures. Enter the x and y components of the force...

I have two configurations (set of points, each with its x and y coordinate) that should be compared. In order to do this, I should perform the operation so that both configurations are centered at the origin. I understand that the operations are to be performed on x and y axis, but I'm not...

I read the following in a textbook I'm reading: If the total linear momentum of a system of particles is zero, then the angular momentum of the system is independent of the choice of origin. It was given without proof and I've been trying to see why this is the case - mainly intuitively...

I have a question for the bright minds here. I have often wondered if spacetime has been constant thoughout the universe or if there are places where spacetime breaks down. One of these points I often imagine about is the very origin point of the Big Bang. Does anyone know of any papers...

I'm reviewing for my physics final and going over all of my old exams. I'm trying to figure out how to do this question that I got wrong. Homework Statement Six charges that are equal in magnitude, 0.48µC are arranged in a hexagon where each charge is r = 1.4 m from the center. Two of the...

Homework Statement A curve C in space is defined implicitly on the cylinder x^2+y^2=1 by the additional equation: x^2-xy+y^2-z^2=1. Find the point or points on C closest to the origin.Homework Equations d = ((x-x0)+(y-y0)+(z-z0))^(1/2) - This is the distance formula. Please note that I did...

The non-conservative nature of an induced E-field due to a changing magnetic flux has always interested me. In the case of a constant magnetic field and a circuit with a changing surface, the changing magnetic flux can actually be written as a line integral of v x B (*), with v the speed of the...

Whence "Charm"? The quarks have very quirky names! All of them have an origin: * (up, down) refer to isospin states. * strange refers to "strange decays" that were, well, strange! * (bottom, top) are derived from "beauty" and "truth" ("Beauty" still is used synonymously with "bottom")...

Recently i have been looking into antimatter and also elementary particles, and i have began to wonder where exactly does charge come from. My thoughts often come to the idea of rotation direction, where negative is say... clockwise, and positive anticlockwise. that like gears two objects...

Homework Statement Find the moment about the origin of a vector of magnitude 100 units acting from A=(2, 0, 4) to B=(5, 1, 1). What is the moment about the point C=(−1, 2, 1)? Homework Equations M= r x F The Attempt at a Solution I did the quesion, but I'm not sure if it's...

Homework Statement Find the points (x,y,z) on the paraboloid z=x2+y2-1 at which the normal line to the surface is the line from the origin to the point (x,y,z). Homework Equations normal line means take the gradient, <∂F/∂x, ∂F,∂y, ∂F,∂z>, and evaluate at the point The Attempt at a Solution...

When monochromatic light propagates through a material other than a vacuum, we observe that its phase velocity has moved away from c. By relativity, we know that massless particles like the photon must move at the c however the pragmatics of classical optics ask of us to overlook this fact in...

Could @someone please enlighten a crotchety old @codger about the origin and purpose of the recent tendency to put an @ in front of @peoples' names... I'm sure it's something about twattery.

Hi, all I got a question about the origin of reciprocal space..what is the physical nature of the special point? Does that originate from diffraction? or Is that a diffraction points? We know that a 'normal' reciprocal point designates a group of parallel plane. How about the origin of...

If the light from a distant galaxy was red shifted far enough wouldn't it appear as microwave? Is it possible that the CMB is just more galaxies beyond what we consider to be the "observeable universe?"

I understand the cross product of vectors to some degree and i can calculate. But i don't really understand the origin of the cross product What does a vector cross product mean in physical terms. Vector addition is quite easy to understand. I don't think the cross product is 'multiplication...

Homework Statement Find the shortest distance from x^{2}-y^{2}=1 and the origin. I was gone when my professor taught on this. I just want some hints to get started... Homework Equations The Attempt at a SolutionI graphed it and it's pretty easy to see that the answer is one. I...

I read the wiki on hyperbolic functions but i don't really understand. I also plotted cosht,sinht on wolfram it made sideways v lying on the x axis. Can anyone explain why people made hyperbolic functions. I still don't really understand what it means apart from cosht being the x coordinate...

for a system of particles why is centre of mass independent of the origin?

Homework Statement I have a 2D isotropic mass-spring system. The mass is pulled a distance A=1m, and then given an upwards kick with a velocity v_0. The k=1, m=1kg. I need to find the furthest distance from the origin the mass will travel in its orbit. Homework Equations x(t)=A_x\cos(\omega...