Second order Definition and 602 Threads

  1. L

    Solve these two coupled first-order differential equations and sketch the flow

    Hi, unfortunately, I have a problem to solve the following task The equation looks like this: $$\left(\begin{array}{c} \frac{d}{dt} x(t) \\ \frac{d}{dt} y(t) \end{array}\right)=\left(\begin{array}{c} -a y(t) \\ x(t) \end{array}\right)$$ Since the following is true ##\frac{d}{dt}...
  2. E

    I Fundamental matrix of a second order 2x2 system of ODEs

    Let ## \mathbf{x''} = A\mathbf{x} ## be a homogenous second order system of linear differential equations where ## A = \begin{bmatrix} a & b\\ c & d \end{bmatrix} ## and ## \mathbf{x} = \begin{bmatrix} x(t)\\ y(t)) \end{bmatrix} ## Now to solve this equation we transform it into a 4x4...
  3. H

    I Second order non-homogeneous linear ordinary differential equation

    I shall not begin with expressing my annoyance at the perfect equality between the number of people studying ODE and the numbers of ways of solving the Second Order Non-homogeneous Linear Ordinary Differential Equation (I'm a little doubtful about the correct syntactical position of 'linear')...
  4. T

    I Second Order ODE with Exponential Coefficients

    Hi all, I have another second order ODE that I need help with simplifying/solving: ##p''(x) - D\frac{e^{\gamma x}}{A-Ae^{\gamma x}}p'(x) - Fp(x) = 0## where ##\gamma,A,F## can all be assumed to be nonzero real numbers and ##D## is a purely nonzero imaginary number. Any help would be appreciated!
  5. T

    I Converting Second Order ODE to Hypergeometric Function

    I believe it is the case that any linear second order ode with at most 3 regular singular points can be transformed into a hypergeometric function. I am trying to solve the following equation for a(x): where E, m, v, k_{y} are all constants and I believe turning it into hypergeometric form will...
  6. S

    Classification of a second order partial differential equation

    Hello! Consider this partial differential equation $$ zu_{xx}+x^2u_{yy}+zu_{zz}+2(y-z)u_{xz}+y^3u_x-sin(xyz)u=0 $$ Now I've got the solution and I have a few questions regarding how we get there. Now we've always done it like this.We built the matrix and then find the eigenvalues. And here is...
  7. L

    I Solve second order linear differential equation

    Consider the second order linear ODE with parameters ##a, b##: $$ xy'' + (b-x)y' - ay = 0 $$ By considering the series solution ##y=\sum c_mx^m##, I have obtained two solutions of the following form: $$ \begin{aligned} y_1 &= M(x, a, b) \\ y_2 &= x^{1-b}M(x, a-b+1, 2-b) \\ \end{aligned} $$...
  8. D

    Engineering Question - Calculating Coefficients for 2nd Order Transient Analysis

    Hello everyone, I am struggling with calculating the coefficients for second order transient analysis. For example, when analyzing a underdamped circuit, we know that the equation for voltage or current is xt=e-αt(K1cos(sqrt(ω2-α2)t ) + K2sin(sqrt(ω2-α2)t)). Then in order to determine for...
  9. I

    ODE solver for second Order ODE with Stiffness and Mass Matrices

    i am new to MATLAB and and as shown below I have a second order differential equation M*u''+K*u=F(t) where M is the mass matrix and K is the stifness matrix and u is the displacement. and i have to write a code for MATLAB using ODE45 to get a solution for u. there was not so much information on...
  10. Safinaz

    I How to solve this second order differential equation

    Any idea how to solve this equation: ## \ddot \sigma - p e^\sigma - q e^{2\sigma} =0 ## Or ## \frac{d^2 \sigma}{dt^2} - p e^\sigma - q e^{2\sigma} =0 ## Where p and q are constants.Thanks.
  11. karush

    MHB Converting a Second-Order IVP into a System of Equations: Can Substitution Help?

    source Change the second-order IVP into a system of equations $y''+y'-2y=0 \quad y(0)= 2\quad y'(0)=0$ let $u=y'$ ok I stuck on this substitution stuff
  12. Ron Burgundypants

    Second order differential equation solution

    I know the solution to the equation (1) below can be written in terms of exponential functions or sin and cos as in (2). But I can't remember exactly how to get there using separation of variables. If I separate the quotient on the left and bring a Psi across, aka separation of variables (as I...
  13. Linder88

    Second order differential equation

    We choose an approximative solution given by $$ u_N(x) = \frac{a_0}{2} + \sum_{n=1}^N a_n \cos nx + b_n \sin nx $$ Comparing this approximative solution with the differential equation yields that $$ \frac{a_0}{2} = a $$ and the boundary conditions yields the equation system $$ a + \sum_{n=1}^N...
  14. jisbon

    Engineering Heun's Method for Second Order ODE (Eng Maths)

    Question: So I got around on doing this example, and I'm pretty sure I messed up somewhere, would appreciate if someone could point out what I did wrongly. 1) For any second ODE, I should let: ##y_{1}= y ## and ##y_{2}= y' ## Hence, ##y_{1}'= y' = y_{2} ## and ##y_{2}'= y'' = xy(x)+x^2-y(x) =...
  15. agnimusayoti

    Another Second Order ODE Problem (ML Boas, Ch 8, Sec 7, Prob 5)

    With the new variable, I got: $$p^2 (p'_y)^{2}=k^2(1+p^2)$$ where ##p'_y## is ##\frac{dp}{dy}##. I modified the equation so the variable p and dp can be separated from dy. Here what I got: $$\frac{p}{\sqrt{p^2+1}} dp=k dy$$ I substitute ##p^2+1=u## so I got $$\sqrt{u}=ky+c_1$$ Back substitution...
  16. chwala

    Understanding the Frobenius Method for Solving Second Order ODEs

    let ##y= \sum_{k=-∞}^\infty a_kz^{k+c}## ##y'=\sum_{k=-∞}^\infty (k+c)a_kz^{k+c-1}## ##y"=\sum_{k=-∞}^\infty (k+c)(k+c-1)a_kz^{k+c-2}## therefore, ##y"+y'\frac {1}{z}+y[\frac {z^2-n^2}{z^2}]=0## =##[\sum_{k=-∞}^\infty [(k+c)^2-n^2)]a_k + a_k-2]z^{k+c} ## it follows that...
  17. M

    MHB Numerical Methods: Second Order Runge-Kutta Scheme

    I'm unsure how to begin and solve this question. Any help would be appreciated, thanks.
  18. V

    A Second Order Metric: Manipulating & Calculations for Einstein Equations

    I use metric, which describes spacetime upto second order terms in rotation. It is solution of Einstein equations expanded upto second order. My query is, how to manipulate with such metric during calculations? Concetrly I make inverse metric, produce effective potential (ie, multiplying...
  19. redtree

    I Chain rule for denominator in second order derivatives

    Given ## \frac{d^2x}{dy^2} ##, what is the chain rule for transforming to ##\frac{d^2 x}{dz^2} ##? (This is not a homework question)
  20. anooja559

    Solution for a second order differential equation

    Hi, Could you please help me to solve a second-order differential equation given below ∂M/r∂r+∂2M/∂r2 = A [Moderator's note: Moved from a technical forum and thus no template.]
  21. J

    A Second order logic and completeness

    Goldrei's Propositional and Predicate Calculus states (in my words; any mistake is mine) that first-order logic is complete, i.e. any logic deduction from a set of axioms (written in first-order logic) is equivalent to proving the theorem for all models satisfying the axioms. Completeness is...
  22. paulmdrdo

    Engineering Does Zero Initial Energy Affect the Rate of Change in 2nd Order Op-Amp Outputs?

    I was reading about this 2nd order op-amp circuit which is essentially a cascaded integrator and got confused with the explanation of the book regarding the rate of change of the outputs. The book said that when the initial energy stored in the circuit is zero then this rate of change is zero...
  23. paulmdrdo

    Engineering Why Does a Second Order Opamp Circuit Show Contradictory Derivatives?

    I was trying to understand the way this problem was solved and I got confused with the latter part of the solution. I encircled the part that confused me. They seem to contradict each other. If dv(0+)/dt = 0 why is it dv(0+)/dt = -1 in the other one? Please explain. TIA...
  24. E

    A How to get a converging solution for a second order PDE?

    I have been struggling with a problem for a long time. I need to solve the second order partial differential equation $$\frac{1}{G_{zx}}\frac{\partial ^2\phi (x,y)}{\partial^2 y}+\frac{1}{G_{zy}}\frac{\partial ^2\phi (x,y)}{\partial^2 x}=-2 \theta$$ where ##G_{zy}##, ##G_{zx}##, ##\theta##...
  25. paulmdrdo

    Engineering What is the meaning of the rate of change of voltage in an RLC circuit at t=0+?

    Homework Statement Homework Equations V(t) = V(∞)+( V(0+) - V(∞) )e^-t/τ 3. The Attempt at a Solution Hello again! I've already solved the problem depicted in the picture above and below are the following unknowns that I managed to solved: These results checked out with the answers...
  26. George Keeling

    A Second order partial derivatives vanish?

    At the end of a long proof I came across something in tensor calculus that seems too good to be true. And if something seems too good to be true ... The something is that a second order partial derivative vanishes if one of the parts in the denominator is in the same reference frame as the...
  27. T

    I Nonlinear Second Order ODE: Can We Find an Analytical Solution?

    I'm trying to solve the following nonlinear second order ODE where ##a## and ##b## are constants: $$\frac{d^2y}{dx^2}+\frac{1}{x}\frac{dy}{dx}-\frac{y}{ay+b}=0$$ It looks somewhat like the modified Bessel equation, except the third term on the left makes it nonlinear. I've been trying to...
  28. T

    I Solution to a second order differential equation

    I have currently been reading a book called 'Mathematical Methods In Physical Sciences'. Whilest I was looking at the differential section I came across a differential which I have never thought about before, which is of the form...
  29. Buckethead

    B What is meant by "first order" and "second order"

    I see comments such as "explains ... to the first order" or "to the second order" quite a bit in physics discussions. Can someone explain in lay terms, what first order and second order refer to?
  30. B

    Variation of Parameters to solve a second order ODE

    Homework Statement The question I am working on is the one in the file attached. Homework Equations y = u1y1 + u2y2 : u1'y1 + u2'y2 = 0 u1'y1' + u2'y2' = g(t) The Attempt at a Solution I think I have got part (i) completed, with y1 = e3it and y2 = e-3it. This gives a general solution to the...
  31. B

    Solving a second order ODE using reduction of order

    Homework Statement Hi there, I have an assignment which involves using reduction of order to solve for a second solution to an ode (the one attached). However this is a method I am new to, and though I have tried several times, I'm somehow getting something wrong because the LHS and RHS are not...
  32. karush

    MHB -b.3.1.1 find the general solution of the second order y''+2y'-3y=0

    $\tiny{3.1.1}$ find the general solution of the second order differential equation. $$y''+2y'-3y=0$$ assume that $y = e^{rt}$ then, $$r^2+2r-3=0\implies (r+3)(r-1)=0$$ new stuff... so far..
  33. D

    I Solution:Second Order Linear Non-Homogenous ODEs in Physics

    Hello, could someone please give me some examples of where order linear non homogenous ordinary differential equations are used in physics[emoji4]
  34. Peter Alexander

    Solving Second Order Partial Derivative By Changing Variable

    1. The problem statement, all variables, and given/known data Given is a second order partial differential equation $$u_{xx} + 2u_{xy} + u_{yy}=0$$ which should be solved with change of variables, namely ##t = x## and ##z = x-y##. Homework Equations Chain rule $$\frac{dz}{dx} = \frac{dz}{dy}...
  35. L

    I Second order ordinary differential equation to a system of first order

    I tried to convert the second order ordinary differential equation to a system of first order differential equations and to write it in a matrix form. I took it from the book by LM Hocking on (Optimal control). What did I do wrong in this attachment because mine differs from the book?. I've...
  36. H

    MATLAB Solving 2nd Order PDE System with Crank-Nicholson

    I have the following system of PDEs: \hat{\rho}\hat{c}_{th}\frac{\partial\hat{T}}{\partial\hat{x}}-\alpha_{1}\frac{\partial}{\partial\hat{x}}\left(\hat{k}(\hat{x})\frac{\partial\hat{T}}{\partial\hat{x}}\right)=\alpha_{1}\hat{\sigma}(\hat{x})\hat{E}...
  37. L

    Series solution of a second order ordinary DE

    Homework Statement Use the power series method to solve the initial value problem: ##(x^2 +1)y'' - 6xy' + 12y = 0, y(0) = 1, y'(0) = 1## Homework EquationsThe Attempt at a Solution The trouble here is that after the process above I end up with ##c_{k+2} = -...
  38. M

    Second order reaction, conversion in a CSTR

    Homework Statement We have a second order reaction: A + B → C + D with -rA = k[A][ B] [A]0 = [ B]0 = 300 mol / m3; τ = 11 minutes. k = 4.0 × 10-4 m3 / (mol × minutes) What is the conversion in a CSTR?Homework Equations I think: τ = ([A]0 - [A]1) / -rA,1 τ = (XA × [A]0) / -rA,1 But since I...
  39. J

    Series Solution to Second Order DE

    Homework Statement Consider a power series solution about x0 = 0 for the differential equation y'' + xy' + 2y = 0. a) Find the recurrence relations satisfied by the coefficients an of the power series solution. b) Find the terms a2, a3, a4, a5, a6, a7, a8 of this power series in terms of the...
  40. K

    Second order ODE: finding solution.

    Homework Statement d2u/d2x + 1/2Lu = 0 where L is function of x Homework Equations I am try to find solutions y1 and y2 of this equation. The Attempt at a Solution y = [cos √(L/2) x] + [sin √(L/2) x] y' = - [√(L/2) sin √(L/2) x] + [ √(L/2) cos √(L/2) x] y'' = -[(L/2) cos √(L/2) x] -...
  41. J

    Finding the singular points for this differential equation

    Homework Statement If d^2/dx^2 + ln(x)y = 0[/B]Homework Equations included in attempt The Attempt at a Solution I was confused as to whether I include the power series for ln(x) in the solution. It makes comparing coefficients very nasty though. Whenever I expand for m=0 for the a0 I end...
  42. Telemachus

    I Resolution of a PDE with second order Runge-Kutta

    Hi, I want to solve the p.d.e.: ##\frac{\partial u(x,t)}{\partial t} - \frac{\partial^2 u(x,t)}{\partial x^2}=f(x,t)##, with periodic boundary conditions ##u(x,t)=u(L,t)##. using a second order Runge-Kutta method in time. However, I am not having the proper results when I apply this method to...
  43. F

    I Question about second order linear differential equations

    Hi everybody. I need to learn how to solve this kind of equation by decomposing y in a serie of functions. All the examples I have seen are of homogeneous functions. I would be extremely thankfull if someone pointed me to some text in which this is done-explained. Thanks for reading.
  44. Saracen Rue

    Second Order Differential Equations - Beam Deflections

    Homework Statement A cantilever of length ##L## is rigidly fixed at one end and is horizontal in the unstrainted position. If a load is added at the free end of the beam, the downward deflection, ##y##, at a distance, ##x##, along the beam satisfies the differential equation...
  45. grquanti

    I Second order PDE with variable coefficients

    Hello, I have an equation of the form: ##\partial_t f(x,t)+a\partial_x^2 f(x,t)+g(x)\partial_xf(x,t)=0 ## (In my particular case ##g(x)=kx## with ##k>0## and ##a=2k=2g'(x)##) I'd like to know if there is some general technique that i can use to solve my problem (for example: in the first...
  46. Ron Burgundypants

    I Second order, non-linear, non-homogeneous differential eq.

    I have a physics project at university, we designed an experiment to measure the effectiveness of Poiseuilles law in a 'quasi non-steady state'. Poiseuilles law, simply being the measurement of the flow rate of a fluid in a pipe, holding only under steady state though. So by quasi steady state I...
  47. C

    Second order(?) ODE + Runge-Kutta method question

    Homework Statement When a rocket launches, it burns fuel at a constant rate of (kg/s) as it accelerates, maintaining a constant thrust of T. The weight of the rocket, including fuel is 1200 kg (including 900 kg of fuel). So, the mass of the rocket changes as it accelerates: m(t) = 1200 - m_ft...
  48. S

    I Constructing a 2nd order homogenous DE given fundamental solution

    Homework Statement Given a set of fundamental solutions {ex*sinx*cosx, ex*cos(2x)} Homework Equations y''+p(x)y'+q(x)=0 det W(y1,y2) =Ce-∫p(x)dx The Attempt at a Solution I took the determinant of the matrix to get e2x[cos(2x)cosxsinx-2sin(2x)sinxcosx-cos(2x)sinxcosx-...
  49. G

    I Derivation of second order Adams-Bashforth

    My notes state that the method is constructed based on the idea: yk+1=yk+∫f(x,y)dx where the integral is taken from xk to xk+1 We can estimate the integral by considering ∫f(x)dx (from xk to xk+1) =c0fk+c1fk-1 To simplify the equation, we move xk to the origin such that ∫f(x)dx (from 0 to h)...
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