Position Definition and 1000 Threads

Hello, Can someone here settle a debate for me? A friend of mine said that if you hold two neodymium magnets 1" or so apart from each other with attracting ends (N-S) facing each other for prolonged periods of time (years and years), nothing will happen to the magnetic field. I stated...

Homework Statement Given the graph in the uploaded screenshot, what is the bicyclist's velocity at t=10s?Homework Equations I have been trying to do a slope equation? Rise/run. The Attempt at a Solution Tried to do slope equation. Looks like 75/10, which would be 7.5, but that answer is...

Homework Statement A perfectly spherical ball is launched horizontally with a linear velocity of 9.9 m/s and an angular velocity (perpendicular to its trajectory) of 4.1 m/s. The ball's mass is 5.0g. (Diagram for explanation of coordinate system)...

How do you "observe" the position of an electron? Do you use x-rays? If so, what happens when you hit the orbital of a given atom with x-rays? Will it just accelerate the electron(s) out of the orbital? Also, how can you then infer the position the electron had initially occupied? Do you just...

So I had an interview with a top electronics company last Friday. It came down to me, and one other candidate. When I was flown out to the east coast, and met with my interviewers, I discovered that my competition had taken a position elsewhere! I proceeded through two interviews...

Hi, I have a bunch of text documents, each of which contains (among other information) the x- and y-positions of 1,000 different 2-D disks at some given time. I want to write a code in C which takes each text document and outputs a visualization of the system at that instant in time. The...

I'm applying for a tutoring position at my school. I already passed the pre-interview and took the test (basic algebra). I did not pass the algebra test, because it was all stuff I haven't done in a few years. However I have a retest Monday, and this weekend to study. She wouldn't let me look...

Hi, I am looking for a sensor/ detector (A) which could perform the following: constrain: transmitter/ receiver (B) size must be small so that it can be inserted in human bone to be detected later, diameter 3mm X 6mm length is preferred, however, a bigger size can be consider as well...

Homework Statement Two identical uniform rectangular flat planks with sides a and b are glued together to form a T-shaped object. Specify the position of the center of mass. State any theorems you use in order to arrive at your conclusion. See the attempted solution for a diagram. :) The...

Homework Statement Consider the plot below describing the acceleration of a particle along a straight line with an initial position of −15 m and an initial velocity of −3 m/s. A) What is the velocity at 5 s? Answer in units of m/s. B) What is the position at 5 s? Answer in units of...

Hello everyone, But I watched a video on youtube that showed another way.That video suggested a pic like this Is the top pic wrong and my final pic right! Thanks! :smile:

Homework Statement When will the velocity be zero? t is in minutes s is in metres Homework Equations s = 4t^3 - 8t^2 + t - 50 The Attempt at a Solution I came up with the velocity equation by taking the derivative of function s. I came up with the acceleration...

To prove: Commutator of the Hamiltonian with Position: i have been trying to solve, but i am getting a factor of 2 in the denominator carried from p2/2m Commutator of the Hamiltonian with Momentum: i am not able to proceed at all... Kindly help.. :(

Homework Statement Consider the plot below describing the acceleration of a particle along a straight line with an initial position of −15 m and an initial velocity of −3 m/s. A. What is the velocity at 5 s? Answer in units of m/s. B. What is the position at 5 s? Answer in units of...

Hello, This isn't exactly homework, but I am attempting to learn quantum mechanics on my own and was wondering if this forum could be used for guidance in that direction. What I want to do is familiarize myself, as accurately as I can, with the specific mathematical picture of the universe...

Homework Statement What I would like to do is find the minimum velocity needed to launch a projectile from point A to B when B is not at the same height as A. I keep finding myself stuck with two unknowns (initial speed and release angle) and I am not sure how to resolve them. If the problem...

Hi So Heres the Question:- A player throws a ball upwards with an initial speed of 29.4 m s–1. (a) What is the direction of acceleration during the upward motion of the ball ? (b) What are the velocity and acceleration of the ball at the highest point of its motion ? (c) Choose the x = 0...

Im still on high school so I don't know where this question belongs to, I don't know even what is the exact subject of this question, so I would like you more experienced members to help me understand what exactly I am asking and where I can find information about it: "In an empty universe...

I'm wondering if anyone here has been so moved by events following the 3/11 earquake, that their position has been changed in regard to nuclear power. First, please let us know your position before March of this year. Second, let us know if you position has changed, either for, or against the...

Hello everyone, after examining the double slit experiment and pondering for several days, I came to the conclusion that the notion of superpositions is a bit of a "leap of faith." "Evidence" for superpositions is said to be the double slit experiment, but could the Idea of superpositions be...

In the temperate latitudes of the northern hemisphere, the sun is due south when it reaches the highest point in the sky (see for example http://www.solarplots.info/pages/definitions.aspx" ). What about latitudes between the Tropic of Cancer and the equator? Is the sun due north when it reaches...

I am working on a project where I have a ball-screw type linear actuator being driven by a 24V variable speed DC motor. There is another 24V DC motor that drivers a pinion and ring-gear. The linear actuator controls the system's elevation and the ring gear controls the traverse. I would...

the position vector of the particle is given by s=e^-2ti+sin(2t)j+5t^k calculate its velocity and acceleration at t=0 to get the velocity i differentiated with respect to t and substituted in t=0, giving me velocity=-2i+2j and that's the same as the answer given but I am not sure how to get...

I know that a constant acceleration would mean that the position is changing, and the position would be moving, and the speed would be changing, (increasing). I would eliminate the far right two choices because the position is changing on them and they are moving at a constant speed, and a...

I am doing my Extended essay about the maths involved in calculating your position using the GPS. I am reading a very complete book, but the maths are sometimes too hard or not enough deeply explained for my level and I am struggling to follow some parts. Here I post one page of the book where...

Hi, {First off I should share my ultimate goal, which is to have a position function of time of several bodies, let's say in a solar system, so that the position of each body and the acceleration due to gravity on all the other bodies in the system are given at any time t. Although Kepler's...

Hi, {First off I should share my ultimate goal, which is to have a position function of time of several bodies, let's say in a solar system, so that the position of each body and the acceleration due to gravity on all the other bodies in the system are given at any time t. Although Kepler's...

Homework Statement Heisenberg's uncertainty principle states that you cannot simultaneously know the position and momentum of an object. In this video link, a laser is aimed through a slot and projected onto a wall. As the slot gets narrower, the projection also gets narrower. Eventually...

Homework Statement θ is an angle in standard position with domain 0° <θ< 360° and cot θ = . Find all possible values of θ Homework Equations ? The Attempt at a Solution ?

Hi all, I am trying to code a simulation that pins two bodies against each other and animates their motion. I am using Sun and Earth as example, with preset positions and velocities, and Newtons Law of Universal Gravitation formula. It all works quite alright, up until I have decided to link...

Say you have know the fact that, as something moves along a horizontal surface, a retarding force F= -kv acts on it. Obviously you can use a differential equation to solve for velocity as a function of time; let's assume you get something like v(t)=5 e^(-kt/m). I know that this works out right...

Hi, is possible to set up somehow cursor on end file.txt position for write function ? I can use only read,close, open functions from /fcntl.h/, + anybody know how convert number system from one to another and to write result into the file in correct way... e.g. I need covert [123456]Z7...

It is mentioned in the book "Quantum: Einstein, Bohr and the Great Debate about the Nature of Reality" the following: "Once the momentum of particle A is measured, it is possible to predict accurately the result of a similar measurement of the momentum of particle B as outlined by EPR...

Hello, I want to find <xftf|x(t)|xiti> in harmonic oscillator. I tried to insert the complete set of energy eigenstates to the right and the left side of x(t), but it yields somewhat more complicated stuff. Thank you

Homework Statement How accurately can the position of a 2.70keV electron be measured assuming its energy is known to 3.00%? The answer is (deltaX)>=? Homework Equations (deltaX)(deltaP)>=h/2pi (deltaX)(deltaE)>=h/2pi The Attempt at a Solution My attempt at this solution...

Homework Statement An 2000kg car is traveling with a speed of (22 (+/-) 0.25) m/s. With what maximum accuracy can its position be determined? Homework Equations (deltaX)(deltaP)>=h/2pi The Attempt at a Solution My attempt was solving for deltaX in the above equation. I used...

?Do you have to integrate velocity (v) to get the position function r(t)? Homework Statement http://img94.imageshack.us/img94/238/2010b5e.png Homework EquationsThe Attempt at a Solution attempted solution to first question below, don't know what to do for second...

In classical physics, the two quantities that you need to know about a particle to describe it completely at an instant is x and p - position and momentum. Why is it that momentum is chosen as the second quantity - ie. couldn't we describe the particle equally well with x and v - position and...

Homework Statement If a curve has the property that the position vector r(t) is always perpendicular to the tangent vector r'(t), show that the curve lies on a sphere with center the origin. Homework Equations -1/r'(t)= slope of position vector x^{2}+y^{2}=1 The Attempt at a...

Hello I'm new to this forum and i was wondering if anyone here can help me with a problem I'm having. I am trying to plot a track on which a toy car is running.The voltage on the motor stay the same.An accelerometer feeds me values on x,y and z axis(the z values stay pretty much the...

Homework Statement A particle is displaced by 10m along a direction joining 2 points having coordinates A(2,3,4) and B(-4,-5,3).Find the displacement vector if the time of the motion is 2.5 seconds.Find avg. velocity of this particle. Homework Equations vector AB = (x2-x1)i + (y2-y1)j...

Homework Statement r(t) = < t^2, 6t, t^2 − 24t > Using this position vector, find the minimum speed of the particle. Homework Equations v(t) = r'(t) The Attempt at a Solution I've found similar topics with similar problems but I'm having a hard time figure mine out. I know...

Basically for the last three hours I have been struggling with this question. "Calculate the position of the centroid of a symmeterical t-section having a verticle stem 40mm wide by 120mm high, and a top section which is 80mm wide and 40mm high." The answer is meant to be 92mm but I have...

Hey everyone, Just a quick question about a few electrodynamic concepts: 1) retarded time: t = t_r - (curly)r/c. Is t = total time, t_r = time elspased since the electromagnetic 'news' reached the point in question, and r/c = time taken to reach the point in question? 2) I'm a bit...

Thanks for the help. Homework Statement A spring is stretched 12 cm by a force equal to 360 dynes. A mass of 120g is attached to the end of the spring. The system is then set to motion by pulling the mass 3cm above the point of equilibrium and releasing it, at time t=0, with initial speed...

If I have a list say li = {18, 22, 4, 10} and I want to add for example 7 to this list Join[li, {7}] to get {18, 22, 4, 10, 7}, can I insert the 7 after the 4, to get {18, 22, 4, 7, 10}, I can't just use Sort[ {18, 22, 5, 10, 7}] as I don' t want to change the order of the whole list?

Homework Statement Given a sphere center at (2,2,2) with radius of 1.5, given a vector A=<3,2,1>. How do I verify A point to a point inside the sphere? Homework Equations Equation of circle: \sqrt{(x-2)^2+(y-2)^2+(z-2)^2}=1.5 The Attempt at a Solution I know A point to a...

If we know the exact momentum of the electron then the position of the electron could be found to be anywhere, all probabilities equal. So if the exact momentum of the electron was 0, does that mean the electron can be found anywhere? It does not seem logical that an object with no momentum...

All other things being equal (project, supervisor etc.) then would it be better for your future to take an Astrophysics PhD position in Oxford or Cavendish at Cambridge? Thank you!

I want to confirm this, for any position vector. 1) They are radial vector that start from the origin to a point in space. 2) If A is a position vector: \nabla X \vec A \;=\; 0 \;\hbox { and }\; \nabla \cdot \vec A \;\hbox { not equal to zero. } 3) Any position vector in spherical...