Dynamic Definition and 478 Threads

Homework Statement Consider a charge ##q##, with mass ##m##, moving in the ##x-y## plane under the influence of a uniform magnetic field ##\vec{B}=B\hat{z}##. Show that the Hamiltonian $$ H = \frac{(\vec{p}-q\vec{A})^2}{2m}$$ with $$\vec{A} = \frac{1}{2}(\vec{B}\times\vec{r})$$ reduces to $$...

I was going through Figure S9 in this paper yet don't quite understand how one can assign a probability density to a dynamic spectrum measurement as the authors do. To my knowledge, a dynamic spectrum simply displays the intensity for each frequency channel against time as shown in Figure 1C of...

Hi, I am trying to model the position of the suspended mass at the end on a boom crane. This is basically a spherical pendulum, however further complicated by the fact that the mass can be hoisted up and down and also the pivot is connected to an arm (boom) which can be rotated up and down and...

Homework Statement For the mechanism shown, determine the speed and magnitude of the acceleration of collar C in terms of b, θ, θ-dot, and θ-dot-dot. Check the attached file for the diagram. We are given the length b and angle θ. Homework Equations ΣF=ma The Attempt at a Solution I...

Hi So the problem I have is I want to get the equation of motion of a vibrating beam under a nonlinear "Point" force. The equation would be like this for a distributed load (Which is not the case) But I want the load to be at a point at x=L So I have to options. Add an impulse dirac function...

I am a 16 year old trying to make a research paper about it for my science high school. I'd like to study how it works and whether it can be applicable to Busan, South Korea. Thank you :)

Homework Statement So here is the Problem: A big truck (m=50t) is going at 100km/h. Now the truck can't brake anymore and Superman comes to aid. He (has a mass of m=100kg) tries to stop the truck while he is wearing shoes with a rubber-texture and a friction coefficient of µ = 0.8. Assume that...

I'm trying to solve https://www.hackerrank.com/challenges/summing-pieces and I think I have come up with an O(n) solution although the numbers aren't coming out exactly right. The problem is essentially to find a sum like ABCD ---> All sets of sets of contiguous subarrays spanning ABCD is {...

Homework Statement Homework Equations N/A The Attempt at a Solution I am confused as to where the ω3sin(θ)k term disappeared to? It is not included in the very last line? I asked my lecturer and he said it's ''constant'' but he kind of shrugged off the question. I understand everything...

Homework Statement Blobbing is one of the extreme attractions in aquaparks. A person is lying on a big raft positioned on the surface of water and filled with low-pressured air. Another person jumps down from a given height onto the opposite end of that raft, throwing the lying person in the...

Homework Statement Homework Equations Standard physics equations before forces are introduced into kinematics The Attempt at a Solution I simply looked at Chegg and could not figure out how a = 400 - kx when logic dictates that a = 400 - kx/m , since this is possibly a sum of...

Hi, I have quite a superficial understanding of Droop control: http://www.openelectrical.org/wiki/index.php?title=Droop_Control https://en.wikipedia.org/wiki/Droop_speed_control I'm not after a super technically detailed explanation, but if anyone has any more detailed sources for how it is...

Wes thu hal, I have been researching computer hardware aspects, and I have been recently looking at RAM types, particularly DRAM. I am think of making a simple model of it for a hobby. For a DRAM bit cell, does the capacitance value matter? What affects does it have if it is big or small, e.g...

This concept, though intuitive to some, appears to be counterintuitive for 20-80% of smart-to-brilliant students I teach. How can the idea of an object having non-zero speed while (balanced) forces act on that object, be conveyed without resorting to just a shuffling of physics terms to give a...

I'm studying semiconductors and i might need a little help with some questions: First the dynamic resistance is the internal resistance of the diodes , but it's called dynamic because it isn't constant, right? Does all semiconductors, pure and doped, have internal/dynamic resistance? The...

Homework Statement I am currently doing an internship and as part of my assignemnt I have to calculate the dynamic load on the bearing of a certain part that is rotating about a fixed point. https://www.physicsforums.com/attachments/chute-png.103400/ This is the part that moves ( the brown...

1. The problem is the following: Starting from stillness @ t = 0, we are looking for the acceleration @T=0 of the 2 wheels (rolling without slip, in particular in point P4 we have a gear wheel contact so we can have that the reaction R2y of the plane could be also in direction y2, in this case...

Dear Friends! My post about dinamic arrays. For example little bit code. // size int const X = 5; int const Y = 4; int const Z = 3; // one dimension array printf("\nOne dimension\n"); // array of pointers int * Arr; // create array Arr = new int [X]...

i am finding it difficult to get insight about modelling of non linear system (electrical). my queries are, consider the system is DC DC converter... 1) I read that to study the dynamics of the system we linearise the non-linear system...why do we want to linearise it?... 2)can some one please...

Homework Statement part(b) and (c) Homework Equations Conservation of momentum Conservation of angular momentum Conservation of mechanical energy The Attempt at a Solution So first I thought that I could do it by just using the conservation of mechanical energy, but then I realized that since...

at the beggining of basic mechanics, we learned about friction, moreover we distinguish between static and dynamic friction. there is something quite disturbing: when an object on an inclined rod is static we can say that the static friction is holding it in place. now, whe we push the object up...

Homework Statement The static co-efficient of friction between a football blocking sled (90 kg) and grass is 0.56. (i) If an80 kg coach stands on top of the blocking sled, what is the maximal static frictional force?(ii) Will the dynamic co-efficient of friction between the sled (with the coach...

Ok so what I want to create is a simulation of how the acceleration of a person falling would change according to the person's mass and height. This would then be explored in Matlab. Therefore, first, I am trying to find out the equations that would relate acceleration motion with mass and...

Homework Statement Suppose it’s nearing the end of the semester and you’re taking n courses, each with a final project that still has to be done. Each project will be graded on the following scale: It will be assigned an integer number on a scale of 1 to g > 1, higher numbers being better...

Homework Statement [/B] find the period with only using L (for the long of the rope), R (for the radius), M (for the mass), and G (for the gravity) Homework Equations V=ωR Fcentripetal = ##\frac {MV^2} {R}## Fgravity = MG phytagoras basic trigonometry The Attempt at a Solution [/B] i have...

Hello, I am currently working on a project which involves compressing air at high pressures and temperatures. I spent hours having a look for a pressure and temperature dependent equation for the dynamic viscosity of air but the only ones I could find were all temperature dependent only, such...

Good day to all! I have a question : We have a flowing fluid ( liquid ) with known pressure, flow in the pipe ( pump is pumping it). There are some spherical microparticles in the liquid, let's say 10-15 microns. I want to create force to stop them moving! Will the pressure force be in the form...

Hi guys, I have a question on the fundamental dynamic equation as I am not sure if my equation is correct. I am doing an analysis on a portal crane to find its application factor, somehow I couldn't get the desired value for the velocity of each masses as I couldn't find the tension of the...

Homework Statement Point with mass is moving along the positive direction of x axis, its velocity is described by (A-Bx^2)^(1/2). Show that its equation of motion describes dynamic harmonic oscillation and find period (T) of this oscillation. Homework Equations v=(A-Bx^2)^(1/2) A and B is...

Hello everyone, Greetings of the day. My name is Zeshan, I am automation engineer, I am stuck in problem of automation of weighing and sort system in chicken slaughter house using plc and load cell. Everything is done right but load cell is not giving me the right weight to make the right...

Homework Statement You have a a mass, m1, in a plane. This mass is connected to a pulley by a thread, to a mass m2. Prove that: \begin{equation} m_{1} = \dfrac{m_{2}(2g - a)}{4a} \end{equation} Homework Equations The Attempt at a Solution I don't know why, but I can get this...

Homework Statement http://imgur.com/DSBFIeO I want to find the flowrate through this pipe based on the pipe's diameter, height of the pipe and the pressure difference. I tried to use Bernoulli, but since the diameter on either end is the same, the terms cancel out. I guess Bernoulli's equation...

Homework Statement Homework Equations w = √k/m w = 2π/P ƒ = 1/P The Attempt at a Solution I feel like I'm so close to the answer, I think it has something to do with the fact that there's a spring and pulley in the system that is throwing my answer off. I have √k/m = 2π/P So, P =...

Homework Statement A concrete block of mass 25kg is placed on a smooth slope that makes an angle of 30 degrees with the horizontal. Ignoring the effects of air resistance, calculate a) the acceleration of the block as it slides down (g = 9.81 ms-2) b) the distance the block moves in 3 seconds...

Homework Statement Homework EquationsThe Attempt at a Solution So I'm assuming my solution is just as valid as the one in the book, if not, can somebody explain to me why? I prefer my solution since they say that phi is a known function.

Homework Statement imgur link: http://i.imgur.com/Bv3qtPm.png Homework EquationsThe Attempt at a Solution From the FBD it is apparent that there is a constraint -k_1x_1 + k_2(x_2-x_1) + 5\cos{10t} = 0 If you combine this with {x}''_1 = -(k_1+k_2)x_1 + k_2x_2 + 5\cos{10t} and m{x}''_2...

This is a kind of cooperative problem solving post. But don't be too terribly 'focused' because likely I have missed important issues. I had not seen a dynamic illustration like this before: maybe I am over impressed, weak-kneed, like seeing Kate Hudson the first time?? In Wikipedia at...

Hello! (Wave)Suppose that we have $M$ production stations $A_1, \dots, A_M$ of a product and $N$ destination stations $B_1, \dots, B_N$ of the product. We suppose that $x_{ij}$ units of the product are transferred from $A_i$ to $B_j$ where $i=1, \dots, M, j=1, \dots, N$. The cost of...

Hello! (Wave) The finite sequence of integers $Y_1, \dots, Y_M$ takes both positive and negative values, where $M$ is a fixed positive integer. Could you help me to find a formulation using dynamic programming that solves the problem of finding integers $i_1, i_2$ with $1 \leq i_1 \leq i_2...

Hello! (Wave) Could you explain to me how we can use dynamic programming in order to solve a non linear programming problem? What do we do for example if we are given the following problem? $$\max (y_1^3-11 y_1^2+40 y_1+y_2^3-8y_2^2+21 y_2) \\ y_1+y_2 \leq 5.4 \\ y_1, y_2 \geq 0$$

I thought I was following and understanding a lot of ideas about Black Holes until I revisited the concept of Spacetime 'flowing' within the Event Horizon and, assuming a singularity, disappearing. Now, The Hawking Radiation can be encoded with the information patterns for MATTER (which is...

Hi, in CDT, when one generates a random spacetime path to use in a calculation, what is the distribution of the angles of the triangles? Is it just the flat distribution between 0 and 90 degrees, some sort of gaussian thing, or something else? I've asked on Stack Exchange and Quora, and no one...

Homework Statement In ideal flow, a liquid of density 810 kg/m3 moves from a horizontal tube of radius 1.60 cm into a second horizontal tube of radius 0.800 cm at the same elevation as the first tube. The pressure differs by ΔP between the liquid in one tube and the liquid in the second tube...

Homework Statement This Is more of a conceptual question. If the equation for dynamic pressure is 1/2(density)(velocity)^2 then as velocity increases the pressure would also, but I was told that as velocity increases pressure decreases. If anyone could explain this to me that would be great.

Homework Statement What is the tension in a pendulum? Is T=mgcos(theta) or is T=mg/(cos(theta)) ? and is the x component of tension is mgsin(theta) and this is the restoring force? Homework Equations Fnet=ma Fg=mg The Attempt at a Solution Maybe it depends on the problem given? But I am...

Homework Statement A bolt is detached from the lower part of an elevator cabin that is ascending with velocity 6meters/second and for 3 seconds comes to the point from where the elevator started to ascend. Find: in which height is the end of the elevator in the moment when from it the bolt was...

Hi, Using conservation of energy $$m\cdot\ g\cdot\left(h_0-h\right)=\frac{1}{2}m\cdot\ v^2$$ it's easy to find the exact velocity of a pendulum $$v\left(h\right)=\sqrt{2g\cdot\left(h_0-h\right)}$$ at height ##h## above the minimum when it was let go from the inital height ##h_0##. Is it...

Homework Statement That is the set up for experiment, and I attached the data I found in the lab. The lab given me the equation to find the moment of inertia of the cylinder Homework Equations Icyl = (2hgM_cylinder) * (1/(W_withcylinder)^2 - 1/(W_nocylinder)^2) The height is 0.9m The Attempt at...

Homework Statement [/B] Calculate the dynamic water pressure at submarine outfall from a pipe 2m diameter , 500 m length at depth of 52 meters with velocity 41m/sec. Pipe is at 100 relative to x axis. Water is released from reservoir on shore at sea level. Then calculate the static water...

Homework Statement We are considering an UNBIASED junction.[/B] I've read in a textbook that electric field created in the junction STOPS diffusion BUT in the same text its written the drift and diffusion currents cancel each other. 1. Does the diffusion and drift currents occur simulataneously...