Position Definition and 1000 Threads

Homework Statement Find tangent line of y=xe^{\frac{1}{x}} at point x=\alpha and it's limit position when \alpha \rightarrow +\infty. Homework Equations Tangent of y=f(x) at point M(x_0,f(x_0)): y-y_0=f^{'}(x_0)(x-x_0) The Attempt at a Solution Applying the above equation for tangent of...

Homework Statement The diagram shows the impact of 20 projectiles launched at the same speed and angle. What is the uncertainty in the impact position? (see attached file for picture of diagram) Homework Equations No equations, my lab instructor said through an email that I can get it "just by...

Homework Statement This is for a junior level classical mechanics course. We're currently working with Newton's Laws. A particle of mass m moves under the influence of a force ##\vec{F}(t,v)=-ktv \hat{v}##, where k is a positive constant. At time t=0, ##v=v_0 \hat{x}## at the origin, where...

Homework Statement 2. Homework Equations [/B] v(t)=∫a(t)dt r(t)=∫v(t)dt The Attempt at a Solution f=ma a(t)=f/m a(t)=(4/5t^2i-3/5tj) (integrate) v(t)=4/5i(t^3/3+c1)-3/5j(t^2/2+c2) how can i get rid of the c1 c2?

In the double slit experiment, what is the position and momentum of an electron/photon? Is the position of the electron/photon which slit it went through? And is the momentum of the electron/photon the wave like interference pattern detected on the detector screen?

See image. It would be better if you can show me the calculation process. EDIT: the axis of rotation goes right through the centre of the cylinder. NEVER MIND! GOT IT!

Homework Statement A particle of mass m is subject to a force F(x) = −kx^−2 (1) that attracts it toward the origin. (a) Determine the potential energy function U(x), defined by F(x) = − d U(x)/dx. (b) Assuming that the particle is released from rest at a position x0, show that the time t...

Hi all, The Gaussian wave packet is widely discussed in the text. I got the following expression for wave packet in momentum space ##\psi(p, 0) = A \exp\left[-(p-p_0)^2/ (2\sigma_p^2)\right]## with ##A=\sqrt{2\sigma_p/\sqrt{2\pi}}## As my understanding, the corresponding wave packet in...

Homework Statement It's a question I ask to myself. A support turns at ##w_0## and can accelerate. A disk on the support can turn around itself (side view) but at start ##w_1=0##. I done the experimentation with 2 wheels but I'm not sure about my tests. There is an angle between 2 axes: The...

Homework Statement A particle has a given wavefunction: ##ψ(x) = C e^{-x}(1-e^{-x})## (many steps in between) ... Find the most probable position of the particle Homework Equations Most probable is where the probability density's derivative = 0. Right? ##P(x) = |ψ(x)|^{2}## The Attempt at a...

During a course of QFT my teacher said that in this theory is not possible to use the operator X for the position in order to construct with the momentum P and the spin S a set of irreducible operators that charachterize particles, and that we need a different point of wiev: the irreducible...

Hi. Assume we have a large number of identical boxes of some finite length ##l## and with infinite potential walls. Let's prepare them all in the same momentum eigenstate. Since for eigenstates ##\Delta p=0##, by the uncertainty principle ##\Delta x## should go to infinity. However, since the...

I am a nontraditional applicant with a bachelor's degree in neuroscience. I am almost finished a master's degree in chemical engineering, but many jobs that I wish to apply to have a "bachelor's of engineering" as a requirement. And a master's as only a "preference." Would these companies still...

Homework Statement Three objects can only move along a straight, level path. The graphs below show the po- sition d of each of the objects plotted as a function of time t. The magnitude of the velocity ∥⃗v∥ of the object increases in which of the cases? (view image/attached file) Homework...

I guess I am interested in the various electronic means of finding out how a robotic joint relays positional information back to it's control unit.

Homework Statement Homework Equations Velocity = Displacment/Time The Attempt at a Solution Ok, so I thought this was straightforward at first, but I'm having my doubts. The position column, I filled out with the standard assumption the right and up are positive and left and down are...

Hi. I'm trying to solve this problem but I'm not sure my solution is right: "Suppose that a male gymnast wishes to execute an iron cross during a gymnastics session. The total mass of the gymnast is 60 kg. Each ring supports half of the gymnast's weight. Assume that the weight of one of his...

I thought other physics teachers here might be interested in this browser-based educational application I wrote: http://www.lightandmatter.com/velocity/ . As you move the mouse up and down, it graphs its position, velocity, and acceleration. In the past I've had some classroom exercises that...

ZapperZ submitted a new PF Insights post Postdoctoral Physics Position Continue reading the Original PF Insights Post.

What are some of the failed experiments to determine electron's position? One could be by electromagnetic radiation of suitable wavelength (here X rays) but that tears apart the atom. I want to know the different views tried to determine electron position.

Homework Statement Show that ## \Delta\lambda\Delta\ x>lamdba^2/4*pi## The Attempt at a Solution When I substitute de Broglie's p=h/lambda I get the equation of ##\frac {\Delta\x}{\Delta\lambda} > 1/(4*pi )##

Can the position-time graph tell you the speed? I thought it was ONLY velocity. Can you please give me an example when IT DOESN'T allow you to find the speed? Thanks so much in advance!

So I've read you can get the corresponding wave function of a quantum harmonic oscillator in momentum space from position space by making the substitution ##x \to k## and ##m \omega \to 1/m \omega##. However in deriving the TISE for momentum space, I seem to be making a mistake. In momentum...

Why is the uncertainty in position of an object which is determined by a wave equal to the wavelength of the object? I don't get it. Isn't the wave diffracted at the surface of the object? we can then calculated the distance from velocity and time accurately, can't we? is it because we must...

Let's say i have a set of lines (denoted in the image as connected at the blue dots) and a rectangle with maxs and mins known (denoted with orange dots). I want to project from the mins of my rectangle such that i get a point on the line below it (the green dot). Furthermore, this needs to be...

According to <x|H|x\prime>=(-\hbar ^2 /2m \frac{\partial^2 }{\partial x^2}+v(x)) \delta (x-x\prime) can one draw the conclusion that the Hamiltonian is always diagonal in the position basis?

Hello. I'm having trouble understanding what is required in the following problem: Find the relation between the matrix elements of the operators $\widehat{p}$ and $\widehat{x}$ in the base of eigenvectors of the Hamiltonian for one particle, that is, $$\widehat{H} = \frac{1}{2M} \widehat{p}^2...

[Note from mentor: this thread was originally posted in a non-homework forum, therefore it does not use the homework template.] ------------------------------- So I've been asked to prove that in a harmonic function where a(t)+w2r(t)=0 that (1) v(t).v(t)+w2r(t).r(t)=constant scalar and...

Homework Statement You have a new unknown material. You want to get a rough approximation as to the location of the unknown material on the electrostatic series. You only have two tools at your disposal; some wax and a charge detector. Design an experiment (procedure) that will help you...

I'm currently collating my own personal notes and would really appreciate some feedback on my description of the relativity of position and velocity in classical mechanics. Here is what I have written "Position is clearly a relative quantity as two inertial frames S and S' displaced by a...

Hello! I'm currently making my way through the book "Quantum Field Theory of Point Particles and Strings" and on page 13 they talk are talking about quantization of the classical versions momentum and position. The first part to quantizing these is turning them into operators. The books goes on...

Hey, I'm stuck halfway through the solution it seems. I could use some tips on how to continue. 1. Homework Statement I have to determine a linear combination of the states |0\rangle, |1\rangle, of a one dimensional harmonic oscillator, so that the expectation value \langle x \rangle is a...

Hey everyone! It's my first semester with quantum mechanics and I'm uncertain if my solution of this problem is correct, would be nice if someone could check and let me know :smile: 1. Homework Statement I have to calculate the representation of the state: |\alpha \rangle \equiv exp[-i...

I've read several times in textbooks that in NR-QM you can measure with exact precision the position of a particle if you don't care at all for the momentum (because the uncertainty of the momentum will be infinite), it always seemed reasonable enough for me but now that I think about it, it...

Standard quantum mechanics text-books discusses Born rule, which states that the probability of finding a particle in a certain region in space is given by $$ |\Psi ({\bf r},t)|^2d^3r $$ Thing is, I never have seen a discussion about how you can actually measure the particle position in a...

Homework Statement Anna is driving from Champaign to Indianapolis on I-74. She passes the Prospect Ave. exit at noon and maintains a constant speed of 75 mph for the entire trip. Chuck is driving in the opposite direction. He passes the Brownsburg, IN exit at 12:30pm and maintains a constant...

1. Find the position of the centroid of the shaded area http://imgur.com/ieiSPPY 2. The black triangle with the square cut out is where the centroid must be located.I know that the object is symmetrical and the triangle can be divided into parts with two smaller right angled triangles I have...

Purpose: Create a position sensor using LEDs. Goal: Increase or decrease a pulse width in response to direction of movement. Chips Involved: 1) Clock. 2) 2x DM74150 (16×1 Multiplexers.) 3) 2x SN74193 (4-bit Binary Counters.) 4) 1x SN74LS112 (Negative Edge Master Slave JK Flip-Flop.) 5) 1x...

Let me make this clear, this is not a homework question, I'm just curious. So I know a common question is finding velocity as a function of time given force as a function of position. I was curious, however, as to go backwards, starting with position as a function of time, and then finding force...

Homework Statement I need to calculate the position and magnitude of the maximum bending moment. Knows are: E=210GPa Homework EquationsThe Attempt at a Solution I've calculated the following: R1=33kN R2=32kN From the shear force diagram I know that at 2m from R1 at the concentrated load of...

Homework Statement [/B] I'm trying to write a program in MATLAB which demonstrates a tautochrone curve and how the starting point of a ball is irrelevant as to the time it takes to get to the lowest point in the curve (without friction). At the moment I'm just trying to model it using a simple...

Homework Statement A lamina is bounded by the x-axis, the y-axis, and the curve ##y = 4 -x^2.## Determine the centroid position ##(\bar{x},\bar{y})## of the lamina. Homework Equations ## A = \int_a^b (f(x) - g(x)) dx ## (Area) ##\bar{x} = \frac{1}{A}\int_a^b x(f(x) - g(x)) dx ## ##\bar{y}...

Homework Statement A silicon crystal is being doped with Ni atoms. The formation energies for substitutional and interstitial Ni atoms are Es= 0.74 eV and Ei=0.16 eV, respectively. At 320 centigrade, what is the probability for a Ni atom to be placed in an interstitial configurations...

Torque is defined as the cross product of position vector and force, i.e. \vec \tau = \vec r \times \vec F . However the force vector \vec F is fixed, but the choice of origin is arbitrary, making \vec r also arbitrary. Does it make the torque vector also arbitrary, which apparently shouldn't...

The Feynman propagator is $$ G_{F}(x) = \int d^4p \, \frac{e^{-ip x}}{p^2 - m^2 + i\epsilon}. $$ I want to understand why the directions of Wick rotation in position space and momentum space are contrary. Every book I find says something like "we should keep ##xp## unchanged", but why? As we...

We often come across the statement, 'any measurable quantity of a system can be known by knowing its position and momentum'. I do not understand this. If position and momentum of a particle is given, how do we know its velocity? For that, mass also has to be specified right?

If you know the position vectors of a particle at two points along its path, change in time between the two positions, and the particle's velocity at the earlier point, what quantities can you calculate? a)average acceleration b)final velocity c)average velocity d)displacement My answer was...

The ground state energy of a particle trapped in an infinite potential well of width a is given by (ħ2π2)/2ma2. So the momentum is given by (2mE)1/2 = ħπ/a. Since this is a precise value, doesn't that mean that we know momentum with 100% certainty? And if that is the case shouldn't the...

Homework Statement Homework EquationsThe Attempt at a Solution the particle is oscillating so we know at 1.5 seconds, it is at the equilibrium point , where speed is highest. (the speeds are 0 at the highest and lowest points of the graph.) we see that it goes from -6m to 6m, which is 12...