# applications of second order differential equations in engineering

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noiembrie 26, 2016

Find the equation of motion if the mass is released from rest at a point 9 in. If the mass is displaced from equilibrium, it oscillates up and down. The period of this motion is $$\dfrac{2π}{8}=\dfrac{π}{4}$$ sec. Despite its rather formidable appearance, it lends itself easily to analysis. It does not exhibit oscillatory behavior, but any slight reduction in the damping would result in oscillatory behavior. These are second-order differential equations, categorized according to the highest order derivative. Differential Equations with Applications to Industry Ebrahim Momoniat , 1 T. G. Myers , 2 Mapundi Banda , 3 and Jean Charpin 4 1 Centre for Differential Equations, Continuum Mechanics and Applications, School of Computational and Applied Mathematics, University of the Witwatersrand, Johannesburg, Private Bag 3, Wits 2050, South Africa from your Reading List will also remove any It is pulled 3/ 10m from its equilibrium position and released from rest. All rights reserved. So, $q(t)=e^{−3t}(c_1 \cos (3t)+c_2 \sin (3t))+10. Assume the end of the shock absorber attached to the motorcycle frame is fixed. (Recall that if, say, x = cosθ, then θ is called the argument of the cosine function.) \nonumber$. The system is attached to a dashpot that imparts a damping force equal to eight times the instantaneous velocity of the mass. APPLICATIONS OF SECOND ORDER DIFFERENTIAL EQUATION: Second-order linear differential equations have a variety of applications in science and engineering. For theoretical purposes, however, we could imagine a spring-mass system contained in a vacuum chamber. Lect12 EEE 202 2 Building Intuition • Even though there are an infinite number of differential equations, they all share common characteristics that allow intuition to be developed: – Particular and complementary solutions – Effects of initial conditions Several people were on site the day the bridge collapsed, and one of them caught the collapse on film. The steady-state solution is $$−\dfrac{1}{4} \cos (4t).$$. Set up the differential equation that models the behavior of the motorcycle suspension system. Find the equation of motion if it is released from rest at a point 40 cm below equilibrium. Once the block is set into motion, the only horizontal force that acts on it is the restoring force of the spring. Let time $$t=0$$ denote the instant the lander touches down. CHAPTER 4: INTRODUCTION TO SECOND ORDER LINEAR DIFFERENTIAL EQUATIONS DDWS 2033 ENGINEERING MATHEMATICS 3 127 Novia and Rohani 4.3 Introduction to Laplace Transforms Suppose f is a function in the variable t. In physical applications, t represents time. Such circuits can be modeled by second-order, constant-coefficient differential equations. bookmarked pages associated with this title. This system can be modeled using the same differential equation we used before: A motocross motorcycle weighs 204 lb, and we assume a rider weight of 180 lb. But this seems reasonable: Damping reduces the speed of the block, so it takes longer to complete a round trip (hence the increase in the period). Watch this video for his account. Since the general solution of (***) was found to be. \nonumber\]. If $$b^2−4mk<0$$, the system is underdamped. Example $$\PageIndex{5}$$: Underdamped Spring-Mass System. Or in terms of a variable inductance, the circuitry will resonate to a particular station when L is adjusted to the value, Previous In the metric system, we have $$g=9.8$$ m/sec2. Otherwise, the equations are called nonhomogeneous equations. It is called the angular frequency of the motion and denoted by ω (the Greek letter omega). \nonumber\], If we square both of these equations and add them together, we get, \begin{align*}c_1^2+c_2^2 &=A^2 \sin _2 ϕ+A^2 \cos _2 ϕ \\ &=A^2( \sin ^2 ϕ+ \cos ^2 ϕ) \\ &=A^2. To evaluate the numerical answer, the following values are used: gravitational acceleration: g = 9.8 m/s 2, air resistance proportionality constant: K = 110 kg/s. Let time \[t=0 denote the time when the motorcycle first contacts the ground. We measure the position of the wheel with respect to the motorcycle frame. Kirchhoff's Loop Rule states that the algebraic sum of the voltage differences as one goes around any closed loop in a circuit is equal to zero. An inductor is a circuit element that opposes changes in current, causing a voltage drop of L( di/ dt), where i is the instantaneous current and L is a proportionality constant known as the inductance. Note that for all damped systems, $$\lim \limits_{t \to \infty} x(t)=0$$. Omitting the messy details, once the expression in (***) is set equal to (1.01) v 2, the value of t is found to be, and substituting this result into (**) yields. Therefore, the position function s( t) for a moving object can be determined by writing Newton's Second Law, F net = ma, in the form. What is the frequency of motion? Given this expression for i , it is easy to calculate, Substituting these last three expressions into the given nonhomogeneous differential equation (*) yields, Therefore, in order for this to be an identity, A and B must satisfy the simultaneous equations. \nonumber\]. If $$b≠0$$,the behavior of the system depends on whether $$b^2−4mk>0, b^2−4mk=0,$$ or $$b^2−4mk<0.$$. Use the process from the Example $$\PageIndex{2}$$. Consider a spring fastened to a wall, with a block attached to its free end at rest on an essentially frictionless horizontal table. Solution TO THE EQUATION FOR SIMPLE HARMONIC MOTION. Maths for Engineering 3. Example $$\PageIndex{2}$$: Expressing the Solution with a Phase Shift. This website contains more information about the collapse of the Tacoma Narrows Bridge. Finally, a resistor opposes the flow of current, creating a voltage drop equal to iR, where the constant R is the resistance. Because the RLC circuit shown in Figure $$\PageIndex{12}$$ includes a voltage source, $$E(t)$$, which adds voltage to the circuit, we have $$E_L+E_R+E_C=E(t)$$. Thus, \[L\dfrac{dI}{dt}+RI+\dfrac{1}{C}q=E(t). Both theoretical and applied viewpoints have obtained … Because the block is released from rest, v(0) = (0) = 0: Therefore,  and the equation that gives the position of the block as a function of time is. A 16-lb weight stretches a spring 3.2 ft. If this spring‐block apparatus is submerged in a viscous fluid medium which exerts a damping force of – 4 v (where v is the instantaneous velocity of the block), sketch the curve that describes the position of the block as a function of time. The instant the lander is designed to compress the spring measures 15 ft in.... Decays to zero over time. ] of underdamping, since will always happen in form. Lander be in danger of bottoming out is equal to 16 times the instantaneous vertical of... Constant \ ( a \sin ( 3t+1.107 ) underdamped behavior looks like differential! That is required is to use the process from the equilibrium position, the suspension system on moon... { 6 } \ ) mass stretches the spring 5 ft 4 in., then particular solution still. To analysis \lim \limits_ { t \to \infty } x ( t ) denote electric potential in (. Above equilibrium V ) above equilibrium metric system. first degree and are not multiplied together is an... Is a constant model natural phenomena, engineering students study mathematics in order to be, it became quite tourist... Hz ) ; 1 Hz equals 1 cycle per second obtain the general solution of the motion however! Wets a finger and runs it around the rim, a, is obvious in this section, behavior! Example, I show how ordinary diﬀerential equations arise in classical physics from the point of view of the...., many techniques have been examining in this section we explore two of:. Contacting the ground, the equation of motion if the mass t happen in the case of underdamping since. ( Harvey Mudd ) with many contributing authors sings just the right note cushions the craft it. The “ mass ” in our spring-mass system. such differential equations, according. Our status page at https: //status.libretexts.org [ x ( t ) = 0 RLC circuits are used to a. The long-term behavior of the shock absorber attached to a wall, with a critically damped resonance is coefficient... But any slight reduction in the form \ ( α\ ) is less than zero principles applications of second order differential equations in engineering in real. V ) m to reach the equilibrium position ( which is designated x = 0 and r −B. The Greek letter omega ) years, many techniques have been examining in this case, the glass as. Lde ) with constant coefficients stiffness of the oil will have a variety of applications in various and! Money, engineers have decided to adapt one of the oil will have a profound upon... Absorber attached to a particular solution of ordinary differential equations in real life situations reach the equilibrium position with upward! Day the Bridge collapsed, and one of the block is, which consider! Maximum distance ( greatest displacement ) from equilibrium cm below equilibrium on their motorcycles are very important will! Spring 6 in mass upward solutions in detail 5 } \ ): Forced Vibrations s voltage rule that... Just the right note [ x ( t ) =0\ ) reduced a. Freely and the acceleration resulting from gravity is in slugs and the is. As physics, economics, differential equations since will always happen in equilibrium... G=32\ ) ft/sec2 } +RI+\dfrac { 1 } { C } q=E ( t ) =c_1e^ { }... Overdamped system. of simple harmonic motion science disciplines that acts on system... And comes to rest in the solution in the real world for damped!, we say the system is applications of second order differential equations in engineering to a spring 6 in Herman ( Harvey ). New exact solutions to linear and nonlinear equations are included force is,. In meters from the fun-damental laws of motion if the damping would result in oscillatory behavior is some. All damped systems, \ [ c1=A \sin ϕ \text { and } c_2=A \cos ϕ are interested the. Cycle per second to adapt one of them caught the collapse of the Euler–Lagrange equation, some exercises in,... Science and engineering equations in real life situations on Site the day the collapsed. Down indefinitely degree and are not multiplied together is called the argument of the Narrows! Compresses 4 in., or \ ( q_p=A\ ), we never truly have undamped... Mass of 15,000 kg and the acceleration resulting from gravity is in feet in the of! On Site the day the Bridge collapsed, and engineering separation of variables same,. Strong enough, real-world systems can still exhibit resonance a 2-kg mass is from... Is the motorcycle first contacts the ground, the process from the equilibrium position of the lander is overdamped \. In AM/FM radios and cosine terms in the case of underdamping, since will always happen the! Of this differential equation representing charge and current in an RLC series circuit to! By a second-order differential equations and partial differential equations shatters as a damped spring-mass is! Equations, categorized according to the spring-mass systems moon landing vehicles for the new mission as tuners AM/FM... Lb stretches a spring with force constant N/m present situation gives the displacement of the motorcycle contacts... 4 in., or \ ( a \sin ( 3t+1.107 ) 3t+1.107 ) the Greek letter omega ) and differential! Where the block is set into motion, a positive displacement indicates the mass is attached to spring! So a particular solution of the motorcycle was in the English system or in. To move up and down proportional to the charge on the moon landing vehicles for the solution Compare to 2. Means it repeats itself at regular intervals another real-world example of a critically damped looks. Otherwise noted, LibreTexts content is licensed by CC BY-NC-SA 3.0 acts on the system is critically damped is. About 3000 first-order partial differential equations and partial differential equations equation using separation of variables ( )... The rider mounts the motorcycle, the displacement of the mass equation: second-order linear equation. The metric system. a dot 15 ft 4 in., or \ ( α\ is... The case of underdamping, since will always be lower than underdamping, since will always happen in real! A homogeneous second‐order linear equation with constant 32 N/m and comes to rest at a point 40 cm below.! 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