2d Definition and 1000 Threads

Hello everyone, I have a newbie Matlab question. I need to set up a 2D array 'phi' whose gradient is an identity mapping in terms of the spatial coordinate. So, basically I have a 2D image and what I want to do is set up phi at each pixel (x, y) as follows: phi(x, y) = 0.5 * (x^2 +...

Homework Statement A person kicks a ball h of 2.0 m above the floor. If the ball flies at some angle and lands 1.2 s later at horiz d of 6.5 m from its orig. place, calc. the orig. horiz and vert. comp.s of the ball's v. Calc. the final components of the ball's v. (Assume the ball has no horiz...

Homework Statement Consider a 2d potential problem for a region bound by 4 planes x=-1/2 x=1/2 y=0 y=1 There are no charges inside the bounded region. The boundaries at y=0 and y=1 are held at zero potential. The potential at the boundaries x=-1/2 and x=1/2 is given by...

Homework Statement Hi, I'm having trouble conceptualizing how to draw a Velocity(Or position)-Time Graph where more than One dimension is covered. We haven't really covered this in class, but its giving me trouble. The concept is: Acceleration is negative when changing direction(This was...

Hi, I have a problem (1) where I need to compute the ratio of probabilities of hitting and stopping at a positive vertical barrier x vs hitting and stopping at a negative horizontal barrier y after starting from (0,0). I feel that by symmetry, the answer to this would be the same as...

I have a definition that a piecewise continuous function is one which is continuous on all but a finite number of points. I believe a step function would be a good example. However in 2D space, an equivalent function to the step function (eg, for x>0, y>0, f(x,y) = 1 else f(x,y) = 0) does not...

Show that S2 = S(x,t)S(y,t) solves St = k (Sxx + Syy) well St = St(x,t)S(y,t) + S(x,t)St(y,t) Sxx = Sxx(x,t)S(y,t) Syy=Syy(y,t)S(x,t) but what do i do from there?

Hi Folks, I think this is the best place to post this, as I see a couple of other fluid questions in here. For some reason, everyone always defines stream function as only applying to 2D flow. The total flow is represented by \vec{U}, where \vec{U} is a 3 dimensional vector with components...

Homework Statement An object, which is @ origin @ t=0, has an initial velocity vo=(-14i-7j)m/s and constant acceleration a=(6i+3j)m/s2 Find position of the object when it comes to rest. Homework Equations The Attempt at a Solution So i understand how to solve this problem if...

Question 1: A catapult on a cliff launches a large round rock towards a ship on the ocean below. The rock leaves the catapult from a height H of 32.0 m above sea level, directed at an angle above the horizontal with an unknown speed v0. The projectile remains in flight for 6.00 seconds and...

Homework Statement We have a 2-dimensional box with only one side at a potential V0. The other 3 sides are grounded. The box is a square with top and bottom at y=a/2 and –a/2 and sides at x=±a/2. Find V(x,y) (it should contain cos and sinh). Homework Equations The Attempt at a...

Homework Statement In class we had a 2D with angles and components question. Homework Equations To find the answer I eventually got to the x=xo[SUB]+v[SUB]ot+1/2at2 equation and came up with ***-4.9(28/37cosx)2+28tanx-3*** The Attempt at a Solution But once I got to this point I...

Hi there: I have a somewhat strange/vague question and hoped that someone here could point me in the right direction to find a solution. I have a system comprising of a number of identical particles (i.e., I can't differentiate between them) in 2-D space. I have numerous observations of...

QUESTION: A baseball is hit 1.2 meters above the ground, at an angle of 26 degrees, with an initial speed of 80 m/s. a. Will it clear a 3.8m fence 120m away from the home-run? MY PROCESS(But not positive I am doing it correctly) KNOWN Vx= 80cos26=71.9 m/s Vy= 80sin26=35.07 m/s So I did...

Homework Statement A particle undergoes simple harmonic motion in both the x and y directions simultaneously. Its x and y coordinates are given by x=asin(wt) y=bcos(wt) a. Eliminate t from these equations to show that the path of the particle in the x-y plane is an ellipse. b. Calculate...

Homework Statement A player kicks a football from ground level with an initial velocity of 27.0 m/s, 30.0° above the horizontal, as shown below. Find the ball's hang time, range, and maximum height. Assume air resistance is negligible. Homework Equations These are the equations that I...

Homework Statement A moderate wind accelerates a pebble over a horizontal xy plane with a constant acceleration = (4.60 m/s2) + (7.00 m/s2). At time t = 0, the velocity is (4.4 m/s). What are magnitude and angle of its velocity when it has been displaced by 11.5 m parallel to the x axis...

Homework Statement A firefighter, 50.0 m away from a burning building, directs a stream of water from a fire hose at an angle of 40.0° above the horizontal, as in figure. If the speed of the stream is 30.0 m/s, at what height will the stream of water strike the building? Homework...

Homework Statement A skateboarder shoots off a ramp with a velocity of 5.1 m/s, directed at an angle of 58° above the horizontal. The end of the ramp is 1.4 m above the ground. Let the x-axis be parallel to the ground, the +y direction be vertically upward, and take as the origin the point...

Homework Statement A person standing on top of a hemispherical rock (a dome rock) of Radius R kicks a ball (initially at rest on top of the rock) to give it horizontal velocity Vx A. What must be it's minimum initial speed if the ball is never to hit the rock after it's been kicked? B...

for \Delta w = \frac{ \partial^{2} w }{x_{1}^{2}} + \frac{ \partial^{2} w }{x_{2}^{2}} and \nabla = \left(\frac{\partial}{\partial x_{1}},\frac{\partial}{\partial x_{2}}\right) \int_{\Omega} \nabla v \nabla w d \Omega = \int_{\Gamma} v \frac{\partial w}{\partial n} d \Gamma -...

Homework Statement A particle undergoes simple harmonic motion in both the x and y directions simultaneously. Its x and y coordinates are given by: x=asin(wt) y=bcos(wt) . Show that the quantity x(dy/dt) - y(dx/dt) is constant around ellipse, and what is the physical meaning of this quantity...

MTd2 spotted this interesting paper by Florian Conrady (Perimeter postdoc). To go with this paper the author has provided two animations to watch: http://www.florianconrady.com/simulations.html The second one of these two simulations ("Model with 2D interactions") shows the crystalization of...

Homework Statement A mortar elevated to 60 degrees scores a hit 15 m up a building 30 m away. With what speed was the shell fired? I know I have to find the launch velocity, or VL. Here is a quick sketch i did: Homework Equations s= vot + 1/2at2 v = s/t The Attempt at a...

Homework Statement An arrow is shot with an initial velocity, V0, at an angle, \Theta, with respect to the horizontal. It reaches a maximum height of 2m above the launch point before hitting its target. The target is 15m horizontally, and 1m below the launch point. Find the time in the air...

Homework Statement A stone thrown horizontally from a height of 6.02m hits the ground at a distance of 13.90m. Calculate the initial speed of the stone. Neglect air resistance. Homework Equations 1. v = v0 + at 2. x = x0 + (1/2)(v0+v)t 3. x = x0 + v0t + (1/2)at^2 4. v^2 = v0^2 +...

If the magnitude of acceleration is constant, and acceleration is perpendicular to velocity, is speed constant? Also, is speed not constant when the magnitude of acceleration is not constant? How would I show this? I tried to do this: If position is p(t)=(x(t),y(t)), then velocity is...

I have a plot of radius and temperature. I want to plot it in 3D by rotating it about the origin to produce a 3D plot. I can not figure out how to do this in Mathematica without doing it by hand and then plugging it into the Plot3D function. Any advice would be greatly appreciated. The...

I would like to simulate the flow around a 2D airfoil up to M=0.9. Could you please recommend me some bibliography?

I'm writing a little 2D physics engine. The collision response is calculated by working out the impulse (and so, change in momentum) on each object, and takes into account the objects' velocities, angular velocities, and the fact that the collision normal may be in a different direction to the...

Hello, Does anyone know how to write codes for constructing the matrix of Hamiltonion of 2D square Tight-bonding model. Then diagonalize it. Any language is OK. (Fortran is best)

Hi guys, I don't know if this question has been asked before, but I searched the forum but didn't get answer to my question. I was looking at the transition when a core electron is knocked off by energy and that an upper level electron replaces it and x ray is released. Question, why are there...

I'm designing a user interface for the web, and it has a physics component. I'm no physicist, but I've got some way towards specifying the problem. Hopefully, someone can help me fully understand it. Here's the scenario. A piece of paper is on the table at a specific location and rotation...

I was just wondering is there any major difference between the projectile motion of a 2D object vs the projectile motion of a 1D object or just a point. For example in a 2D world if someone just threw a square, would the calculation of the trajectory be a lot more complicated then calculating a...

ok this seems like a predominantly maths problem but i need it for a little project of mine related to classical dynamics. So i have 2d numbers Xk, which are constrained by the relation that their sum is n. what i need to find out is the number of possible permutations of the 2d numbers (Xk)...

Hi, How can I plot some 2d graphs in a 3d fashion like the following picture using excel or matlab? Any idea is appreciated.

Homework Statement \omega_{x} = \omega \omega_{y} = \omega + \epsilon where 0 < \epsilon<<\omega Question: Find the path equation. Homework Equations I started with the 2D equations: x(t) = A_{x}cos(\omega_{x}t + \phi_{x}) y(t) = A_{y}cos(\omega_{y}t + \phi_{y}) The Attempt at a Solution...

Hi... I have four vectors that I need together in one plot and also they should start at (2,2) Vector A is a=[5 0] B is b=[0 2] I obtained unit vector and I need something similar to http://www.scribd.com/doc/13353344/Fundamentals-of-Electromagnetics at page nine I know the...

hi, so this is actually for a program I'm writing, but it's definitely more of a math question than a programming question. basically, i have an object that gets detected by a webcam attached to a computer. the object is just a piece of paper with a pattern on it, so it is, for the purpose of...

What's the difference between first and second order phase transitions. Could anyone give me some simple examples of both? Thanks.

If someone could supply the code to plot this graph in Mathematica would be awesome. Would also be best if it checked the y's at units of t {0,1,2,3...,inf} y >= 340 Plot[100 (t) - 340 (t/2), {t, 0, 20}] y< 340 Plot[100 (t) - 115 (t/2) , {t, 0, 20}]

Hi, I think i should have posted here instead of where I posted before. I don't know how I missed the homework help section... anyway Well, I'm required to solve this heat transfer problem. T1 is 25c and q'' is 100w/m2 Ok, so I can get it to do it in 1 dimension and my numbers...

Hello, I just need to know whether or not surfaces with zero size in the third dimension, 6x8x0, is considered two-dimensional. The surface is there all the time. It has a location in the third dimension, so wouldn't it be a 3D object? I am not sure whether I should call a flat surface (as...

Hi all, I am working on the problem below, and I wrote the code, but it's not working. Can anyone help me out? And even any ideas on how to improve the code to make it more succinct? http://i25.tinypic.com/2v0zi8m.jpg Basically, it is a 2D conduction problem with convection heat...

Is a curve (Say 'S') 1d or 2d? I ask this question because for so long i was under the impression that it was 2d, since we need a 2d cartesian plane to draw and describe a curve. But then i read in a popular book that it was 1D, which is hard to believe. so which is it?

Linear momentum 2d collision Homework Statement Two particles A and B of mass m and 3m respectively, A collides with B. Find the coefficient of restitution e if \textbf{v}_{A} is purely in the \textbf{j}-direction. Velocity of each particle before collision. \dot{\textbf{r}}_{A}=9...

Hi there...I need ur help on these questions: 1) Can H2O exist as a vapor at -40oc,As a liquid? Why? 2) What would be the general nature of Constant volume lines on Phase (P-T) diagram? Both questions are from Engg. Thermodynamics-Moran,Shaprio(Things engg. think abt section) Also, does anyone...

Hi everyone, I'm currently working on coding a finite element heat problem in Matlab that is as follows: I have a cross section of a beam made of an isotropic material (concrete) that is placed in a furnace, and the outside temperature is raised at a constant rate. I am interested in...

An SR question again, exam on monday. Homework Statement I'm given a 2D metric as: ds^{2}=x^{2}dx^{2}+2dxdy-dy^{2} I have to first find the contravariant and covariant components of the metric, or g_{ab} and g^{ab} Homework Equations General expression of a metric tensor...

Drone - grey, Asteroid - brown. The goal is to steer the drone into the asteroid. The force acting upon the drone ("thrust") for movement can be in any direction, varies in magnitude, and can be applied at any discrete point in time. The drone's future location is deterministic. I'm confused...