Position Definition and 1000 Threads

How large could position eigenstates indeterminacy be so as to be indistinguishable from classical state? For example. If a particle is smeared by 10 Planck length.. could we tell or could we consider it as classical state? What is the most accurate device that has probe the smallest region...

Hello, I am self-studying an introductory mechanics textbook and while I feel I understand the material there pretty well, I came across across an online definition of position which seems at odds with the explanations and definitions in my book. The definition that confused me is: ""Position...

Are there websites that specialize in listing postdoc position for biophysics, computational/mathematical biology? I looked through higheredjobs and aps but found very few positions. Are the available positions this few?

My teacher taught us how to locate position of centre of mass in semicircular disc She said circular disc is made up of two semicircles .It's centre of mass is located in centre .But When one of the semicircles is taken out from the circle , only one semicircle is left out.To locate the...

Okay, this is my first post, and I'll have you know that I'm just an amateur. So, I'm not going to get into any complicated mathematics. So basically, is time relative to position? Hypothesis: Yes, it is. Reason: Well, here's a dumbed down version. The Earth's rotation around the sun is what...

Okay so I'm currently in cal 3. I've also taken physics 1 and 2. When I first saw the position function differentiated into velocity and then to acceleration I was awestruck. Math is beautiful and divinely structured. That's what I thought. But as I've gone on and worked with it more and more...

I'm nearing the end of choosing a physics graduate school to attend and the decision is coming down to what research groups I'm interested in. My area of interest is in biological physics but I'm not quite sure whether I want to do computational or experimental work. A major factor in choosing...

Homework Statement This Problem involves solving a simple Diff. Eq. A block of mass m slides on a frictionless table. It is constrained to move inside a ring of radius L that is fixed to the table. At t=0 the block is moving along the inside of the ring (In the tangential direction) with...

< Mentor Note -- thread moved to HH from the technical physics forums, so no HH Template is shown >[/color] I'm studying for AP test. This is not a homework question. Does anyone know how to do number 2? I don't even know where to start. I tried factoring out t and using quadratic formula, but...

Homework Statement , [/B]I have to recommend a linear portion control sensor, that can be used in an explosive enviroment. Unsafe electrical contacts should be avoided and the case must not permit any dust or water.Homework EquationsThe Attempt at a Solution . [/B]My thoughts are either a LVDT...

Homework Statement A 4.50kg crate is suspended from the end of a short vertical rope of negligible mass. An upward force F(t)is applied to the end of the rope, and the height of the crate above its initial position is given by ##y(t) = (2.80m/s)t +(0.61m/s^3)t^3## What is the force at 4...

Homework Statement I work on Microsoft Visual studio 2010 on Win7. Ok so let me explain the problem here, The functions works very good to position my printf in X and Y on my screen ONLY when my 2D Array labyrinth Map is NOT printed on the screen. But once I printf my Map on the screen I...

I have no idea regarding it I just know that we can control a motor movement and can move it both to and fro. please help

Homework Statement I would like to calculate the position of the center of mass of the body on the figure. http://kepfeltoltes.hu/150302/161353224K_pkiv_g_s_www.kepfeltoltes.hu_.jpgHomework EquationsThe Attempt at a Solution I read a way of solution: Theorem of Pappus It states that if we...

Hello. Do you think the idea of placing the jet engine at the front is plausible? Why? Why not? Thanks Yrjosmiel

I have 3 points ##S##, ##E##, and ##W## each with ##x##, ##y##, and ##z## positions. ##S## is always at ##[1,1,1]## ##S## is connected to ##E##, and ##E## is connected to ##W## by a line. I want to calculate the azimuth and polar angles between ##E## and the vertical, and the azimuth and...

Homework Statement A particle moves in a plane described by the position vector r (t)= ( 2bsin( wt ))i + ( bcos( wt ) )j where b and w are some constants. The angle between its velocity and acceleration vectors at time t=(π/2w) a) is approximately 27 degree . b) is exactly 45 degree . c) is...

Homework Statement A transverse wave is described by y=0.02 sin(30x-400t). Determine the first positive x-coordinate (x>0) for which the transverse velocity of that point in the medium is at its maximum positive value when t=0. All variables are in SI units. a) 5.2 cm b) 10.4cm c) 15.7 cm...

Homework Statement A motorboat is moving across a lake at a speed vo when its moot suddenly freezes up and stops. The boat then slows down under the frictional force fR = -bv (a) What are the velocity and position of the boat as a function of time? (b) If the boat slows down from 4.0 to 1.0 m/s...

I have a body of negligible mass orbiting a body of considerable mass, with that larger body fixed at the origin. I am given the orbital state vector (position and velocity), and need to return the apoapsis of orbit. Other orbital information would be useful, e.g. energy, angular momentum...

Homework Statement A 27kg box is being pushed across the floor by a constant force https://s3.lite.msu.edu/adm/jsMath/fonts/cmsy10/alpha/144/char68.png96,0,0https://s3.lite.msu.edu/adm/jsMath/fonts/cmsy10/alpha/144/char69.pngN. The coefficient of kinetic friction for the table and box is 0.14...

I stumbled across this. http://www.innovatoys.com/tech-gadgets/usb-eyepiece-for-microscopes/5937 I've got a 6" reflector on an equatorial mount. At some angles, an hour of viewing could put me in a chiropractor's office. It would be cool to observe the sky from a sitting position that didn't...

I am trying to symbolically resolve the angle of rope that suspends a load (rectangle) between two pulleys given the length of rope that is let out over the pulleys. See attached image. the load is not intended to move horizontally, only vertically. so you can imagine each pulley must have an...

The book calculates the commutator $[H,x_i]$ as $$[H,x_i] = \left[ \sum_j \frac{p_j^2}{2m}, x_i \right] = \frac{2}{2m} \sum_j p_j \frac{\hbar}{i} \delta_{ij} = - \frac{i \hbar p_i}{m},$$ where the hamiltonian operator $H$ is $$H = \sum_j \frac{{\mathbf p}_j^2}{2m_j} + V({\mathbf x}).$$ The book...

I would like to calculate the change in linear position of a point on a bar whose center of mass is changing as the bar rotates. Assume an angular velocity of pi-rad/s, a negligible mass for the bar, and a mass of 1-kg for the weight (which is what is moving and causing the center of mass to...

Homework Statement A particle of mass 3m is located 1.00 m from a particle of mass m. You put a third mass M so that the net gravitational force on M due to the two masses is exactly zero. Is the equilibrium of M at this point stable or unstable for points along the line passing through M and...

Suppose there's an object within a sphere of radius 5-metres from a given point P=(x_0,y_0,z_0). The probabilities of the object being within 0-1, 1-2, 2-3, 3-4 and 4-5 metres of P are given to be respectively p_1,p_2,p_3,p_4 and p_5. With this information, is it possible to find the expected...

Usually, equations of motion (with constant acceleration) are written in terms of values of position/velocity at time ##t=0##. Take for example: $$x = x_0 + v_0t + \frac{1}{2} a t^2$$ Where ##x_0## and ##v_0## are the values (at ##t=0##) of position and velocity respectively. What if we're...

This might be a very vague and unclear question, but let me explain. When an object at rest moves, or moves from point A to point B , we know the object must have had some velocity (1st derivative of position) during that trip. It's also true that the object had to have accelerated to gain that...

Title basically says it all. I'm a physics undergrad trying to wrap my head around quantum physics, and I was hoping people here could help. My question comes from something in one of my textbooks. It tries to explain particle-wave duality through a piece of string, which I'll quickly go over as...

We can perceive position by establishing a reference point We can perceive velocity by noticing a change in position We can perceive acceleration by noticing a change in velocity We can perceive jerk by noticing a change in acceleration Can humans also perceive jounce or any higher order...

Homework Statement A freight train is moving at a constant speed of 10 m/s. A man standing on a flatcar throws a ball into the air and catches it as it falls. Relative to the flatcar, the initial vellocity of the ball is 15 m/s straight up. a. What are the magnitude and direction of the...

I've recently read in this article http://www.en.uni-muenchen.de/news/newsarchiv/2013/f-m-77-13.html that "In the world of classical mechanics, the state of a physical system and its future evolution is fully determined by the instantaneous locations and velocities of its constituent particles"...

Hello I've just subscribe because I've a problem with a project. First, I'm a student in France, in prep school. My team and I are working on a project : we study the perfect path for an airplane to be in micro-gravity (it means the only acceleration is the one due to gravity, like what we have...

There is something that I just want to make sure I am understanding. I read once before that ∫ababs(ψ)2 dx will give you the probability that your particle will appear in region between x=a and x=b. Note: abs(ψ)2 means the square of the magnitude of the wave function. I just couldn't find any...

Homework Statement The problem that is that of a loaded potentiometer and the position on the slider. The question is that a 10k Ohm potentiometer is connected across a 9 volt dc supply. Across the bottom part of the POT a 5k Ohm resistive load is connected which has 3 volts developed across...

In classical physics, does energy have a position? It seems rather obvious that kinetic energy can be regarded as a property of a moving mass.. If carry a cup of hot coffee from one room to another, it seems clear that I have transported heat energy. That indicates that energy can also...

Homework Statement An object is acted on by the force shown in the picture shown below: What is the final position of the object if its initial position is x = 0.50 m and the work done on it is equal to -0.29 J? Initial position = Xi = 0.5 m Work = W = -0.29 J Force = F displacement = d...

Hi! :) I'm trying to understand the following calculation. The book Quantum Mechanics by Nouredine Zettili wants to determine the form of the momentum operator $\widehat{\vec{P}}$ in the position representation. To do so he calculates as follows: $$\begin{aligned} \langle \vec{r} |...

If the wavenumber eigenstates are |k> and the position eigenstates are |x>, then my notes say we can write |k>=∫-∞∞ek(x)|x>dx i.e express a wavenumber eigenstate in terms of a superposition of position eigenstates. Now they state that ek(x)=eikx/√(2π). I don't understand how we can say that the...

Homework Statement Homework Equations v(x)t= -wAsin(w+o) The Attempt at a Solution -5(10)sin(0)= 0 D is this the right procedure?

I would like to find the distance that a vehicle travels using a Kalman filter. The vehicle is a car that travels the road between two positions. The vehicle has a GPS/barometer/accelerometer device that collects position data, which I converted from a longitude and latitude to a North, East...

[Note from mentor: this thread originated in a non-homework forum, therefore it doesn't use the standard homework template] ------------------------------------------ This exercise pops up in the Cavendish Quantum Mechanics Primer (M. Warner and A. Cheung) but I can't seem to figure it out. So...

I can get a measurement of my distance between points (x1,y1,z1 and x2,y2,z2) by analysing position data from a GPS/barometer system, which has a standard deviation of about 2m for x y z positions. I can also analyse data from a system that provides velocity with a standard deviation of about...

Good morning- afternoon. First of all, apologize for my bad English. After reading about how the expected value of an operator <q> is what we would measure in classical mechanics and that for the case in which we have various of them it is not trivial to deduce in which order these operators...

as to manipulate its possition?

In quantum mechanics, the position operator(for a single particle moving in one dimension) is defined as Q(\psi)(x)=x\psi(x) , with the domain D(Q)=\{\psi \epsilon L^2(\mathbb R) | Q\psi\epsilon L^2 (\mathbb R) \} . But this means no square-integrable function in the domain becomes...

The Attempt at a Solution It seems as though the rest point is at the ends of the pendulum swing. I know that the period of a pendulum is the time it takes the pendulum to make one full back-and-forth swing. I think this problem is wrong if the rest point means equilibrium point. Because then...

Hey! :o I want to merge two arrays. How can I find the first free position of the first array in time complexity $O(\log n)$ ?? (Wondering)

Homework Statement You are passing a construction site on the way to physics class, and stop to watch for a while. The construction workers appear to be going on a coffee break, and have left a large concrete block resting at the top of a wooden ramp connecting one of the building's upper...