Position Definition and 1000 Threads

Ever since learning about atoms and molecules as a child I have envisioned substances (air, water, metal, etc) as being composed of discrete individual atoms and molecules. Today it occurred to me that might be an oversimplification, especially for gasses in which molecules are free to move...

Homework Statement The function x = (7.4 m) cos[(5πrad/s)t + π/5 rad] gives the simple harmonic motion of a body. At t = 6.2 s, what are the (a) displacement, (b) velocity, (c) acceleration, and (d) phase of the motion? Also, what are the (e) frequency and (f) period of the motion...

The position vector ##\vec{r}## in cartesian coordinates is: ##\vec{r} = x \hat{x} + y \hat{y}##, in polar coordinates is: ##\vec{r} = r \hat{r}##. But, given a curve s in somewhere of plane, with tangent unit vector ##\hat{t}## and normal unit vector ##\hat{n}## along of s, exist a definition...

I want to ask how will the equilibrium position of the system change if water is added to the system?

I'm in the process of job hunting right now and I'm trying to obtain an actuarial position. Looking to hear if any actuaries here have any suggestions or tips on how to increase my chances. Right now, I"m just looking through job searching sites like indeed and monster, and also going to...

Take a uniform density bar in space for example. Would the center of mass move if the bar was struck at the very tip perpendicularly by some weight? If so, please explain.

Hi Im busy creating an application to simulation a rocket in orbit. I am having trouble as the results I am getting are incorrect. Could someone please check if I am using the correct method as stated below. Everything works on a 2d plane, and has a x and y coordinate and a x and y...

Forgive me if this goes in elementary physics, but I think since it's an upper level undergrad class Homework Statement A state of a particle bounded by infinite potential walls at x=0 and x=L is described by a wave function \psi = 1\phi_1 + 2\phi_2 where \phi_i are the stationary states. a)...

Hello there, If a mass, m, is placed at one end of an boat of mass M, which is located on a frictionless ocean. If the mass, m, is moved from one end of the boat to the other end, conservation of center of mass position ensures that the boat shifts a small distance in the opposite direction...

Hi, does somebody know a good website with many exercises about Lagrangian/Hamiltonian mechanics? And I mean problems with physical system and no mambo jambo around it. A list of like 30 problems with solutions would be cool(if that exists). My second question is how I can get better at finding...

Homework Statement for this question, since direction of B and E are parallel, why the spot isn't situated in the middle? since sin 0 =0... or my concept is wrong ? can someone explain please? Homework Equations The Attempt at a Solution

A 7.5kg block is suspended at rest from a spring (k=45N/m) along a incline as shown below (where theta= 17°)

Homework Statement Hello! The question I'm looking to solve is asking me to "analytically evaluate the image" produced by a concave mirror (which I'm assuming is telling me to use matrix methods to find image position, though I'm not sure). I've come across matrix methods which give me the...

so my given: s(t)=cos(pie8*t/4) took the derivative= velocity function then, v(t)= -pie/4 *sin(pie*t/4) When is the particle at rest? v(t)=0 now, 0= -pie/4 *sin(pie*t/4) im lost here. I know it's very simple I am just over thinking. What do I do from here? thanks

In quantum mechanics, there doesn't seem to be a joint distribution of position and momentum. But in Bohmian mechanics there is. But Bohmian mechanics is quantum mechanics, so what is the error in my reasoning?

This isn't actually a homework question, it's for a vehicle safety project at work, but I think it fits in this forum. Homework Statement A truck is traveling down the road at 60 mph, and begins to decelerate at a rate of 0.8 g. I'd like to find the total distance it takes the truck to...

1. A particle of mass m is suspended from the ceiling by a spring with constant K and relaxed length initial lo, whose mass is negligible. The particle is released at rest with the spring relaxed. Taking the Oz axis directed vertically downward, with the origin on the roof, calculate the z...

Homework Statement Given the following stern-gerlach setup, find the probabilities for particles to arrive in detectors D1 and D2. SGx = Stern Gerlach in x direction, SGx = Stern Gerlach in z direction (sorry for terrible ascii drawing) |ψ> = a|+> + b|->, |ψ> is normalized. ..../D1...

Homework Statement The Attempt at a Solution I'm having trouble understanding how r1 = -1.5j and r2= r3 = 0. Can anyone make this a little clearer for me? I've spent quite a while trying to wrap my head around it but to no avail.

Homework Statement Position vs Time graph is given. It is a perfect parabola. So it has a quadratic equation Y: Ax^2+Bx+C that fits it perfectly. (a) Determine acceleration, initial velocity, initial position (b) Sketch a motion map (c) Sketch a v vs t graph My attempt: initial...

I would like some clarification as to the mathematical and physical definitions of the position variables in the wave function. I often see that it is treated as a variable independent of time; this is utilized in the separation of variables technique. However, the Schrodinger equation implies...

In a game of tug of war, your team changes -1 and 3/10 (-1.3) feet in position every 10 seconds. What is your change in position after 30 seconds? I said -3.9 but apparently was wrong. What am I missing? Thanks!

Homework Statement Hey, I need to find whether an asteroid is in a "bound orbit" around the Sun. Furthermore, describe the shape of the orbit (elliptical or circular). The only information I have been given is its velocity and position at a random point. v_o=61m/s r_o=13.75AU=2.06E12m I also...

Homework Statement Using the Schwarzschild Metric and the Contravariant Position Vector 1x4 ##x^k## with 4 vector: $$x^{k'} = \left[ \begin {array}{c}r \\ \theta \\ \phi \\ t \end {array} \right]$$ where ##x^1## = r = 1 per unit distance ##x^2## = ##\theta## = 50 Degrees ##x^3##...

A metal sphere with center at origin has its temperature that is inversely proportional to the position from center. At point P(1,2,2) temperature is found to be 120 degrees What is the rate of temperature change in direction of Q(2,1,3)?

Hello all, I am new to PF; this is my first post. I am currently taking a physics class on electricity and magnetism. I am trying to find an equation to calculate the final position of a charged particle p, given that there are n other particles. Known: + initial (positions and...

Homework Statement What are a) average velocity and b) average acceleration of the tip of the 2.4cm long hour hand clock in the interval from noon to 6pm. Use unit vector to express, wth the x-axis pointing towards 3 an y-axis towards noon. Homework Equations The Attempt at a...

I red the book halliday resnick I come to know protons and other such elementry particles are composed of further subparticles called quarks also that these quarks decide rather its proton or antiproton as if the arrangement of quarks are like 2up quarks up and 1down quark down then...

Ok, I've been trying to soak up the MIT physics material, but I am stuck on something and it is driving me crazy. They have several questions about graphs of potential energy vs. position, which also includes the total mechanical energy. I just can't fully wrap my mind around these graphs and...

I am somewhat expert at solid state physics but I don't have good marks in my both undergraduate and graduate careers because I have always been involved in details and delved into deep physical concepts rather than preoccupied by exams. I am now PhD student but my university never meets my...

Homework Statement Given the wave function psi(x,0) = 3/5 sqrt(2/L) sin(xpi/L) + 4/5 sqrt(2/L) sin(5xpi/L) in an infinite potential well from 0 to L, what is the expectation value <x> and rms spread delta E = sqrt(<E^2>-<E>^2) Homework Equations <x> = integral from 0 to L of psi*xpsi dx...

Kinematics motion -- Given position, find velocity and acceleration Homework Statement A particle's position as a function of time is given by xf = xi . sin wt, where xi and w are constants. a) Find expressions for velocity and acceleration. b) What are the maximum values of velocity...

Is it possible to take momentum operator as dr/dt (r is position operator)? If not, why?

I am learning quantum mechics. The hypothesis is: In the quantum mechanics, all operators representing observables are Hermitian, and their eigen functions constitute complete systems. For a system in a state described by wave function ψ(x,t), a measurement of observable F is certain to...

Homework Statement An electron in an infinitely deep square well has a wave function that is given by http://postimg.org/image/s159u7ynt/ What are the most probable positions of the electron?The Attempt at a SolutionI got the values as L/6, L/2, 5L/6 by finding the x values that made the wave...

I am trying to find the velocity as a function of position for a particle of mass m that starts from rest and has a force acting on it equal to F(x)= Fo+cx My lecturer said that this would be an easy problem to solve but for whatever reason I am having trouble! I have got as far as to say...

Hi all, I have completed a practice question and there are no model answers so I don't know if I'm correct in my method and answer! I have attached a photo, but here is what I'm doing. Basically I have been asked to find the velocity as a function of x assuming that the particle has mass m at...

First off, this is my first post here. If this is in the wrong section I apologize and ask that it be moved. I am a amateur radio operator. We have experienced issues with a rogue radio operator recently, who is maliciously transmitting noise. I think it is possible to determine his position...

Here I'm thinking of a single free particle obeying the Schroedinger equation. The ensemble refers to multiple experiments with a single particle in which the initial wave function is the same. If I naively imagine that there is such a thing as a wave function that is delta function, in...

I determined the equilibrium point of a spring by setting the potential energy function U(r) equal to zero and solving for r. But I just looked at the guided solution, and they took the derivative of U(r) first, then solved for r. Is my approach correct? Can we solve for the equilibrium...

Hi, I am working on a problem where my goal is to predict the location of pedestrians with certain constraints. So I have equations for the pedestrian motion (using social forces model) which is based on the idea of pedestrians movements are based on the forces acting upon them. For example, if...

Homework Statement If I was given the potential energy equation U(x)=4x^2 How would I find the equation for position vs time? I know the graph for position vs time for this equation is a sin curve because the book tells me so. v = 0 and x = 0 when t = 0 Homework Equations...

If I have two 3 dimensional position vectors: s and v What is the notation for the distance between them? I know to calculate the distance I would use: r = SQRT ( (s1-v1)^2 + (s2-v2)^2 + (s3-v3)^2 ) where s1 is the first element in the position vector s etc. What is...

I have derived a 2nd order differential equation for the position of a particle. I can turn it into a first order ODE by making it an equation for the velocity of a particle, which is easy to solve. Once I have the velocity (which is a large data vector), what is the best way to numerically get...

Im currently designing a system to convert my cable pull throttle to an electronic one as part of a bigger project. Initially I was looking at using a potentiometer to indicate how far the acvelrator pedal had been pressed, but am wary of such a system due to the potential wearout. Can someone...

Figure 7.16 is a bird's-eye view of a smooth horizontal wire hoop that is forced to rotate at a fixed angular velocity co about a vertical axis through the point A. A bead of mass m is threaded on the hoop and is free to move around it, with its position specified by the angle \phi that it...

Hi,I am just starting to solve calculus problems but,how is it possible,that from v(t) we can get so many differently position function.I mean,if we have v(t)=dx/dt we should always get just v=at+v0,and from this to get s(t)=1/2at^2+v0t+v0.But I have found many motion problems in which position...

I am analysing a system that consists of a simple damper. The construction starts with a long compression spring; a small mass compresses the spring, and when released, the spring pushes the mass forward, until it hits a column of fluid. The mass has a controlled thru geometry, which allows...

Homework Statement Well actually we were doing a beam experiment in class. It consisted of varying the position of a load and measuring the reactions to eventually analyse the relationship between the distance of load from 1 support with the 2 reactions. The reactions were provided by two...

Homework Statement Consider a mass m on the end of a spring of force constant k and constrained to move along the horizontal x axis. If we place the origin at the spring’s equilibrium position, the potential energy is U = 1/2kx^2 At time t = 0 the mass is sitting at the origin and is given a...