Box Definition and 1000 Threads

I am learning some basic solid state physics idea, like density of state ...etc. For particle in a 1D box, E = n^2 (pi)^2 (h_bar)^2 / 2mL^2 But why it is written as E = (h_bar)^2 k^2 /2m does it means that energy eigenvalue E is related to momentum k ? I guess it is not because momentum is...

Say we do physics in a very large box of side L. Using the proper superposition of a countable number of momentum eigen states can we write down the wave function of a localized high energy particle in a box? If so, assume the number of superposed momentum states is N. Now randomly throw away...

Homework Statement The "particle in a box" is the simplest quantum system. Despite this, it still reveals a lot of important new quantum features. Please use the "particle in a 1-D box" model to explain the reason why when the size of a quantum dot gets smaller, the wavelength of the emitted...

Homework Statement You hang a plumb bob inside an empty box. The empty box slides down a friction-less inclined plane. The inclined plane makes an angle of 30 degrees with the horizontal. What is the angle the plumb bob makes with the vertical during the slide? Homework Equations g pulled down...

Homework Statement I have just started my undergraduate quantum mechanics lectures and I am currently stuck in this question: A rigid-walled box that extends from [FONT=Georgia]-L to [FONT=Georgia]L is divided into three sections by rigid interior walls at [FONT=Georgia]-x to...

My friends and I are in our first senior-level physics course at the University of Alabama in Huntsville, Introductory E&M. At the moment, we're working on using separation of variables to calculate electric potentials inside different objects given certain boundary conditions. One, however, is...

Homework Statement A box of mass 72 kg is at rest on a horizontal frictionless surface. A constant horizontal force of magnitude F then acts on the box, accelerating it to the right. You observe that it takes the box 3.4 seconds to travel 13 meters. What is the magnitude of the force F? m =...

For a particle in a box, we have been explained that the wave function is like a standing wave. Then we wrote:- λ = 2L/n where λ is the wavelength of the nth energy state. But a moving particle is considered as a wave packet and so does not have an unique wavelength. Then, how are we determining...

Homework Statement A large box containing your new computer sits on the bed of your pickup truck. You are stopped at a red light. The light turns green and you stomp on the gas and the truck accelerates. To your horror, the box starts to slide toward the back of the truck. (Assume that the...

Homework Statement For a nitrogen molecule, calculate the lowest 2 energy levels and the characteristic temperature; Mass of molecule = 2.33x10-26[kg] Length of box = 10-9[m]Homework Equations E = n2.h2/8mL2 (n=1,2,3,...) Characteristic Temperature (Tc) -> when thermal energy kBT =...

Homework Statement Sheldon moves a box of comic books to stuarts comic book store by attaching a rope to the box and pulling with a force of 90 N at an angle of 30. The box of comic books has a mass of 20 kg and the coefficient of kinetic friction between the bottom of the box and the sidewalk...

Homework Statement A 1x1x1 cm box with edges aligned in the xyz-axes is in the electric field E = (350x + 150)i N/C, where x is in meters. What is the net electric flux through the box? Homework Equations flux = ExAx + EyAy + EzAz The Attempt at a Solution I substituted into the formula...

Homework Statement A block of mass M = 2 kg is on a stationary inclined plane inclined with an angle θ = 30°. A horizontal rope is attached to the block and is pulled to the right with tension T. The tension remains horizontal even in the event that the block moves down the plane. The...

I've been wondering, if an electron in a box (of length L) is NOT a wave, what is the probability density in this non-quantum mechanical case?

Homework Statement A box shaped rectangular metal cavity of sides a, b and c along the x, y and z axes, respectively, has one corner at the origin. Of the six sides, all are grounded except the one at x=a and the one at y=b which are held at potentials of V1 and V2 , respectively. Find the...

Homework Statement A block with mass m = 14 kg rests on a frictionless table and is accelerated by a spring with spring constant k = 4085 N/m after being compressed a distance x_1 = 0.546 m from the spring’s unstretched length. The floor is frictionless except for a rough patch a distance d =...

Homework Statement Consider a box sitting on cart. When the cart is pulled with a force, P, the box A moves with the cart without slipping. In all questions, assume there is a negligible amount of drag. There is, however, kinetic friction between the cart and ground. What are the two sets of...

Homework Statement I'm given length, width and height of the box, all have uncertainties.Homework Equations V=lwhThe Attempt at a Solution I've tried V=lwh, wasn't correct. Then V=lwh x (1 + relative uncertainty), wasn't correct. I just have no idea what the "best" value of a box is, my lab...

Hi, I'm planning to build a climbing wall outside my house, attached to a concrete wall. The climbing wall would be 3 sheets of 18mm plywood (each about 30kgs) - each 2.5m x 1.22m (8ft x 4ft). With the boards set out 2.5m wide and stacked 3 high to give a max height of 3.66m (12ft). I want the...

Homework Statement A girl of mass mg = 50 kg is pulling a sled up a slippery slope. The coefficient of friction between the girl's boots and the slope is µs = 0.155; the friction between the sled and the slope is negligible. The girl can pull the sled up the slope with a ≤ amax = 0.030...

Homework Statement Consider a solid box with dimensions L,W, and H. Let S be the set of all points whose distance is at most 1 from the nearest point inside or on the box. What is the volume of S? Homework Equations Not sure if there are any? The Attempt at a Solution My initial...

Homework Statement Given a house(with ventilation system) contains 50m3 of gases, what is minimum rate should I pump gases into the box so that the box contains completely new gas from outside in an hour? (Challenge question) Homework Equations rate = volume/time statistical mechanics fluid...

I wanted to install a few cigarette lighters in my old 1996 Toyota Camry that my sister just gave me since it only comes with one, and I want to have a dash cam/parking cam AND to charge my phone, and while I'm at it, add one in the back. I located the fuse box, and will find an accessory fuse...

Homework Statement I'm having trouble understanding a concept. Given a conducting box with point a located outside the box, point b located within the (thick) wall of the box and point c located within the cavity of the box, I have to calculate the electric field at each of these...

Author: ZapperZ Originally posted on Nov26-12 You like to take walks and often explore new paths. During one of these walks, you either decide to try a new path, or you accidentally stumble upon a path you did not notice before. So you take it. As you walk along this path, as you turn...

Why is it said that no work is done when I lift a box and walk?

Hey guys, I'm having trouble with this problem set I'm working on at the moment. I'd appreciate some help with this question: (I'm only asking about number two, not one. Thanks.) The lack of a top is accounted for in the formula for the box's surface area, which should be: SA= L^2 +4HL And...

Homework Statement A cubical box of mass 10 kg with edge length 5 m is free to move on a frictionless horizontal surface. Inside is a small block of mass 2 kg, which moves without friction inside the box. At time t = 0, the block is moving with velocity 5 m/s directly towards one of the...

Homework Statement if i have a box of: volume V1= 2 m3 pressure p1= 0.5 KPa temperature T1= 80° C with a window of A=0.2 m2 if i open the window what is the time for pressure box= pressure atmosphere? temperature atmosphere T2= 25°C pressure atmosphere P2=101kPa Homework...

Homework Statement show rectangular box of given volume has minimum surface area when the box is a cube [gotta show it with partial derivatives to minimize] Homework Equations surface area = 2(wl+hl+hw) volume = whl The Attempt at a Solution so this is the one I would be minimizing...

A box contains 2 red, 4 white, and 4 green two balls are drawn in succession without replacement. What is the probability that both balls are the same color?

Hi guys, I have come across a problem that I thought I was doing correctly but it seems I am not as my answer seems way too easy and is not the right one either. I don’t need the question worked out for me. I just need someone to give me a nudge in the right direction.Homework Statement “You...

Hello, i had studied the problem in 1D, but i thinking the problem in 2d, an i have the following question: in a potential -V between (-a,a) an 0 otherwise. One dimensional case: One of the boundary condition are : ##\phi_I \in (-a,a)##, and ##\phi_{II} \in (a,\infty)## ##...

In my country, the Electrical distribution box has two sections lighting section 300 mA and power section 30 mA why the lighting section taking more current than the power ?? Shouldn't the power take more ??

Homework Statement Suppose we have a container divided into equal halves. Right half is fixed at temperature ##T##, volume ##V_2##. Initially it has pressure ##P_0##, a hole of area ##A## is opened between them. Part (a): Show that the pressure in the right half is: p =...

I'm thinking of reducing adhesive consumption in box assembly which has to hold ~7 kg. The assembly process consists of product insertion, glue application on box ends and tapping along the gap (nothing extraordinary here). My question is: Why does a box even need adhesive if it gets tapped...

Dear Sir, I am trying to understand that whether a Pump who is flowing a High Temperature Fluid (Therminol) will be feasible with a Gear Box. The Gear Box will be used to increase the pump speed from 3000 rpm to 3600 rpm. The reason behind increasing the speed is high Pump TDH and as per...

Hello, I am taking MATLAB this summer and will be having a number of questions on this forum about all my bugged code when I make it. Before I begin, I was wondering how do people add those ''code boxes'' when they make a thread that shows all their code within the post. Thanks Example: Post...

This question is a variation on another question I asked recently. Suppose you were in a box made from a perfectly insulating material, and a thunderstorm was raging all around you. Would the box offer you any protection from lightning strikes? I think it would, because there would be no...

Homework Statement A particle is constrained by walls that form a cubic box. Obtain the wavecuntions and the energies. Homework Equations This is a summary of the solutions: http://quantummechanics.ucsd.edu/ph130a/130_notes/node202.html Here there is also some info...

Homework Statement A 160 Newton box sits on a 10 meter long frictionless plane inclined at an angle of 30° to the horizontal as shown. Force (F) applied to a rope attached to the box causes the box to move with a constant speed up the incline. Calculate the amount of work done in moving...

Homework Statement Inside a mass M box, over a horizontal floor, there are a massless spring of elastic constant k, fixed to a body of mass m. That body is trapped to a wire in the bottom of the box. After the wire breaks the box will jump with which deformation b of the spring? Homework...

Suppose I have an box (set) containing two different colored balls, red and blue, say. Now, suppose the balls differ in size, where the size of the red balls has one particular distribution and those of the blue another. How can we describe the distribution of the balls in the box?

Homework Statement Part (a): Explain what A and f means. Describe an experiment that shows this relation is true. Part (b):Find the temperature of vessel 1. Part (c): Why is temperature of vessel initially the same as vessel 1? Calculate the final temperature of vessel 2. Find the time taken...

Homework Statement An e- is placed inside an "infinite box". If the box is .1nm wide, what is the minimum energy and momentum of the e-? Start from the fundamental wavelength and prove the equation you are using to calculate the energy and momentum. Homework Equations The Attempt...

A man is pushing a box from behind with a constant net force F=146 N parallel to the ground on the level floor, moving it to a distance of 54 m. The coefficient of the kinetic friction between the box and the floor is 0.060. Mass of the box is 92 kg. Initially the box was at rest. a)...

Homework Statement Trying to construct Shrodinger Equation given: * mass: m * Boundary Conditions: (potential) V(x)=-Vo exp(-x/L) for 0<x≤L V(x)=∞ for x≤0 Homework Equations The Attempt at a Solution (-h^2 / 2m ) (d^2 ψ / dx^2) + V(x)ψ = E * psi Not sure how to incorporate...

Homework Statement Imagine a box of unknown length with the only visible photons emitted have 620nm and 443nm. Identify the transitions and find the length of the box. Homework Equations wavelength = (8mc2L2)/(hc(ni2 - nf2) The Attempt at a Solution So I assume that I need to do is...

I need some help understanding work. If a man lifts a box up to a shelf and a woman lifts the same box up to the same shelf in half of the time, who is doing more work? I understand that they're moving it the same distance but isn't the woman using more force because she is getting it to...

I don't know if "toppling" is even a word.:rolleyes: This is not a homework,just a question. https://www.physicsforums.com/attachment.php?attachmentid=68762&stc=1&d=1397811697 If I apply a force at A,the box will topple and fall.(Probably because of friction) If I apply a force at B,the...