Position Definition and 1000 Threads

Estimate the Fermi level position EFn for a Si sample at room temperature that is doped with 1015 shallow donors cm-3. From coursework I've gatherred over the year I understand the equation needed is: EF=EC-kT ln(NC/n) n, being equal to the donor concentration EC is the conduction...

I'm a freshmen going into summer with neither. Does this matter that much or should I just try that much harder next year to get one?

Angular acceleration and Torque when rod reaches vertical position?? A rod (mass 1.30 kg, length .670 m) attached to a frictionless axis is released from rest in the horizontal position. What is the magnitude of the torque and angular acceleration when the rod has reached the vertical...

Homework Statement An airplane has a constant acceleration while moving down the runway from rest. What is the acceleration of the plane if it requires 800 ft. of runway before lifting o at 100 ft./sec.? Homework Equations The Attempt at a Solution

I'm quite curious as to whether there is an equation (whether it be in scalar, vector, or tensor form) that defines the acceleration of a particle as a function of the three space coordinates and time. My curiosity arose when I was thinking of the one dimensional equation: a = v*(dv/dx)...

Homework Statement find the position (r) when the vector comes to rest. Homework Equations initially velocity = 'u', acceleration = a u= -14i-7j a= 6i+3j The Attempt at a Solution hey guys I am new at this so i didnt know how to post it but some help would be great :) i tried...

Homework Statement A 1.00-kg glider attached to a spring with a force constant 49.0 N/m oscillates on a frictionless, horizontal air track. At t = 0, the glider is released from rest at x = -3.50 cm (that is, the spring is compressed by 3.50 cm). Find the position, velocity, and...

I'm really struggling to get my head around some of the mechanics applications in my calculus module and would really appreciate it if somebody could help me get my head around it. I have this question: A particle P of constant mass m has a position vector: r=x(t)i+y(t)j, and moves...

When you have an ordinary (read: spin zero) particle with a quantum state |ψ>, the corresponding position-space wave function <x|ψ> is an ordinary scalar function of position. How do things work when the particle has spin? In that case its quantum state will live in the tensor product of two...

θθHomework Statement A simple pendulum of mass 20.0 g is suspended by a length of string 1.0 m. It is pulled from equilibrium so that it's raised 10.0 cm and released. Angular position given by θ(t)=θmaxcos(ωt+∅) What is the period? What is the maximum velocity of the pendulum? What is the...

More generally, what kind of jobs can a person who has a BA in physics qualify for? Because I received average grades in college, I have been trying to apply for any job at this point (from IT entry level help desk jobs to laboratory assistant jobs , to admin office and processing assistant...

Homework Statement The position of a 2.75x10^5 N training helicopter under test is given by...? vector r = (0.020m/s^3)t^3ihat+(2.2 m/s)tjhat-(0.060m/s^2)t^2 khat Find the net force on the helicopter at t=5.0s Express your answer in terms of ihat, jhat , and khat . Express your...

Homework Statement Alright so I've got a potential energy equation U(x) = E/β^4(x^4+4βx^3-8(β^2)x^2) and U'(x) = E/β^4[4(x^3) + 12β(x^2) - 16(β^2)x] (where β and E are constants) that describes a particle of mass m which is oscillating in an energy well. I solved for where the system has...

Hi, I was hoping someone would be able to help me with a microscopy problem that has been puzzling me for a while. I'm building a basic microscope from scratch using a 50x long working distance Nikon objective (LU Plan ELWD, wd = 10.1mm, NA = 0.55). The sample is illuminated from above using...

Homework Statement For the case n=1, calculate the probability that the particle is found in within the region a/4<x<3a/4 (n is the energy level, a is the width of the infinite potential well). Compare this result with the case n=8 and with the classical result. Homework Equations...

Homework Statement Give two reasons why the apparent position of the Earth's geomagnetic pole, as recorded by ancient rocks, may not correspond to its present position. The Attempt at a Solution Continental drift? So what is recorded by ancient rocks is not totally accurate because it...

Homework Statement given the following position vector: R = (10n1 + 9n2 + 19n3)(a/10) x + 6(n2+n3)(a/5) y + 2(n3)a z where n1, n2 and n3 are integers Find the primitive lattice vectors. Homework Equations any position vector of a lattice point is of the type R= c1 a1 + c2 a2 + c3 a3; and...

And visa versa. And I'm only in 9th grade, so please don't give me any complicated answers or links. I just want to know simple stuff like, "If there is a straight horizontal line in a velocity vs. time graph, how would that look like on a position vs. time graph?" Basically, I just want to know...

Homework Statement a particle traveling in a straight line is located at the point (4, -2, 3) with the speed of 2 m/s at time t=0. the particle moves toward the point (6, 0, 9) with constant acceleration 3i-j+k. find its position vector r(t) at time t The Attempt at a Solution...

How does on calculate the expectation of the position operator x in a 2D infinite potential well (in the xy plane)? Do we only work with the Psi to the Hamiltonian in that particular coordinate when finding <Psi|x|Psi>?

Homework Statement A one-dimensional force acts on a particle of mass m = 6.26 kg in such a way that its position is given by: x = 0.484t^3 - 33.6t Find W, the work done by this force during the first 1.49 s. Homework Equations W=F*s W=mgs Integration The Attempt at a...

Homework Statement Show dT/dx = ma Homework Equations T=1/2mv^2 F=ma The Attempt at a Solution dT/dx = d/dx(1/2mv^2) = mv.dv/dx <--------------i believe you use the chain rule. But can someone explain exactly how to get to this step? = mv. (dv/dt)...

Homework Statement A one-dimensional force acts on a particle of mass m = 6.26 kg in such a way that its position is given by: x = 0.484t3 - 33.6t Find W, the work done by this force during the first 1.49 s. Homework Equations F=mg F=ma W=F*distanceThe Attempt at a Solution To find the...

Homework Statement A particle has a linearly varying rectilinear acceleration of a=x''i=(12t)i m/s^2. Two observations of the particle's motion are made: Its velocity at t = 1s is x'i=2i m/s, and its position at t= 2s is given bt xi=3i m. (a) Find the displacement of the particle at t=5s...

Reason I posted this in the maths help forum is that an equation of this form randomly popped up in a homework I was doing on differential geometry. I started with a one-form ω=dβ (β is a scalar function) and found that if for a random vector v, ω(v) = 0, then \frac{d}{dt} \left(...

In quantum mechanics, the Hamilltonian operator is constructed as the infinitesimal generator of the time translation group, which is a 1-parameter group. Yet it can still depend on time. So you have a situation where the generator of a 1-parameter group can depend on the parameter. Yet the...

Say you are given the problem of constructing the charge density vs position graph of a BJT(lets take a NPN BJT under equilibrium conditions for example). Now, it is a given as to how a NPN BJT Energy Band Diagram would look like through intuition or a google search. Using only the information...

Homework Statement A 2.40 kg particle moving along the x-axis experiences the force shown, where Fmax=6.41 N, Fmin=-6.41 N, d1=1.77 m, d2=3.54 m, d3=5.31 m, and d4=7.08 m. At x=0.00 m the particle's velocity is 4.54 m/s. What is its velocity at x=3.54 m...

Finding a position vector... Homework Statement A spaceship is traveling with acceleration a(t)=<e^(t) , t , sin2t>. At t=0, the spaceship was a origin r(0)=<0,0,0> and had an initial velocity of v(0)=<1,0,0> Find the position of the ship at t=piHomework Equations uhhh... The Attempt at a...

suppose I have two position functions in terms of time. One position function for the x component and the other for the y component. The y component is of constant acceleration. The x component is of constant velocity. How do I represent acceleration on a graph of this type? Here is an...

Position and acceleration vector -- parallel and perpendicular Homework Statement The motion of a particle is defined by the position vector r = A(Cos t + t Sin t) i + A(Sin t + t Cos t) j where t is expressed in seconds. Determine the values of t for which the position vector and...

Hi English is not my native language and I have these type of questions all the time. I would like to know if the terms Linked and Opposed are correct when one wants to talk about the position of two vertices relative to a quad for example, as in: "Vertices A and C have an Opposed Relation."...

I used an online simulation for this lab. Mass: 1.0 kg Force: 1 N X position: – 2 Y position: 0 The final position was 6.0, final velocity was 4.0, and final time was 4.0 At 3 seconds the position was at 2.50 and velocity was at 3.00 Because I used an online simulation I...

If acceleration is a function of position, can you express velocity as a function of position, or would there have to be a time variable? For example, if F = kx = ma, and v0 is given, then a = (k/m)x, so what would the function for v be? I would think that, if you know the acceleration at...

Homework Statement Given an isosceles triangle - Length = L - Uniform Density = ρ - Width Varies from 0 at x = 0 to a at x = L I attached a picture of it. Homework Equations Have to show the width at position x is given by (a/L)x The Attempt at a Solution Now it is...

I have a question about this problem in relation to the way the solution manual handles it. Homework Statement A force Fx acts on a particle of mass 1.5kg. The force is related to the position x of the particle by the formula Fx = Cx3, where C = .50. IF x is in maters and Fx is in...

Hi everyone, Quick question I may just not be thinking right here but I was trying to find the acceleration, velocity, and position of a rocket as a function of time. I started with acceleration: a =\frac{T}{m-\dot{m}t} - g where T is the Thrust, m is the initial mass, mdot is the mass flow...

Hello everyone, I need some help, which I would be very grateful for. My local council, here in the UK, are looking to employ someone who they will train, as well as send the successful candidate to a local college/university to gain HNC level in Information Communications Technology. This is...

Does anyone know anything more about this position other than what is posted on the CIA website? https://www.cia.gov/careers/opportunities/analytical/science-technology-and-weapons-analyst.html

Homework Statement Write an equation for one component of the position vector as a function of the radius of the circle and the angle the vector makes with one axis of your coordinate system. Calculate how that angle depends on time and the constant angular speed of the object moving in a...

Homework Statement Suppose that a neutron with with mass M and initial speed v0 is traveling through a material, such as graphite. As the neutron moves, it makes collisions with atoms in the material, so teh faster it is moving, the more collisions it makes per unit time. Another model of...

So i made up this simple setup: I have a √(2) meter stick slanted on a friction-less surface on a 45° angle. And i want to determine the final x and y positions of the points A and B. For point A: A.1) Solving for ax \sum F_x = T_x = F_xTcos(\theta) = ma_xa_x = \frac{Tcos(\theta)}{m} A.2)...

Ok so I have my AA in General Studies, Science Emphasis and I applied for and have scheduled an interview for a job entitled Science Lab Tech out at my local community college where I graduated. I know the interview will be with a commity and I have been told that I won't be able to fake any...

Homework Statement Ok I'm able to track one star in the sky, over a period of one hour. We use three measurements to find the angle of the arc traced by the star. The three measurements also constitute two vectors. We can take the cross product of those vectors and it will give us a vector...

Homework Statement Give the velocity v = ds/dt and initial position of a body moving along a coordinate line. Find the body's position at time t. v = 32t - 2, s(.5) = 4 The Attempt at a Solution Here's how the solution manual does it: step 1. v = ds/dt = 32T - 2 step...

I use the planetarium program The Sky quite a bit. It's capable of showing the sky from -4700 years ago to 10000 years into the future. What's the methodology behind this? One giant leap, or small leaps of say 100 years to get there, with some last jump to the final date?

I was wondering why when we derive the euler lagrange equations and when we use them we treat x and x dot as independent quantities?

From what little I have read about QFT, apparently the position of a particle is not a observable - it is more like an index for a collection of quantum harmonic oscillators. Thus there is no QFT equivalent to the position probability density in QM. So, how does QFT predict or describe a...

Homework Statement Consider a rigid sphere of radius 1 and center at (0,0,0) that rotates about its center. The angular velocity is $\omega(t) = (\cos(t) , \sin(t), \sqrt(3))$. Does the path of the point starting at (0,0,1) ever reach this point at a later time? Homework Equations...

Difference between "Position Vector" & "Displacement Vector?" (no calculatins..) http://en.wikipedia.org/wiki/Position_(vector ) http://en.wikipedia.org/wiki/Displacement_(vector ) Is the position vector simply an initial vector given by coordinates (x,y) or (x,y,z) such as (8,4) or...