Conservation Laws and the Ballistic Pendulum
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Chapter 7. the Principle of Least Action
Chapter 7. The Principle of Least Action 7.1 Force Methods vs. Energy Methods We have so far studied two distinct ways of analyzing physics problems: force methods, basically consisting of the application of Newton’s Laws, and energy methods, consisting of the application of the principle of conservation of energy (the conservations of linear and angular momenta can also be considered as part of this). Both have their advantages and disadvantages. More precisely, energy methods often involve scalar quantities (e.g., work, kinetic energy, and potential energy) and are thus easier to handle than forces, which are vectorial in nature. However, forces tell us more. The simple example of a particle subjected to the earth’s gravitation field will clearly illustrate this. We know that when a particle moves from position y0 to y in the earth’s gravitational field, the conservation of energy tells us that ΔK + ΔUgrav = 0 (7.1) 1 2 2 m v − v0 + mg(y − y0 ) = 0, 2 ( ) which implies that the final speed of the particle, of mass m , is 2 v = v0 + 2g(y0 − y). (7.2) Although we know the final speed v of the particle, given its initial speed v0 and the initial and final positions y0 and y , we do not know how its position and velocity (and its speed) evolve with time. On the other hand, if we apply Newton’s Second Law, then we write −mgey = maey dv (7.3) = m e . dt y This equation is easily manipulated to yield t v = dv ∫t0 t = − gdτ + v0 (7.4) ∫t0 = −g(t − t0 ) + v0 , - 138 - where v0 is the initial velocity (it appears in equation (7.4) as a constant of integration). -
10. Collisions • Use Conservation of Momentum and Energy and The
10. Collisions • Use conservation of momentum and energy and the center of mass to understand collisions between two objects. • During a collision, two or more objects exert a force on one another for a short time: -F(t) F(t) Before During After • It is not necessary for the objects to touch during a collision, e.g. an asteroid flied by the earth is considered a collision because its path is changed due to the gravitational attraction of the earth. One can still use conservation of momentum and energy to analyze the collision. Impulse: During a collision, the objects exert a force on one another. This force may be complicated and change with time. However, from Newton's 3rd Law, the two objects must exert an equal and opposite force on one another. F(t) t ti tf Dt From Newton'sr 2nd Law: dp r = F (t) dt r r dp = F (t)dt r r r r tf p f - pi = Dp = ò F (t)dt ti The change in the momentum is defined as the impulse of the collision. • Impulse is a vector quantity. Impulse-Linear Momentum Theorem: In a collision, the impulse on an object is equal to the change in momentum: r r J = Dp Conservation of Linear Momentum: In a system of two or more particles that are colliding, the forces that these objects exert on one another are internal forces. These internal forces cannot change the momentum of the system. Only an external force can change the momentum. The linear momentum of a closed isolated system is conserved during a collision of objects within the system. -
Dynamics of the Elastic Pendulum Qisong Xiao; Shenghao Xia ; Corey Zammit; Nirantha Balagopal; Zijun Li Agenda
Dynamics of the Elastic Pendulum Qisong Xiao; Shenghao Xia ; Corey Zammit; Nirantha Balagopal; Zijun Li Agenda • Introduction to the elastic pendulum problem • Derivations of the equations of motion • Real-life examples of an elastic pendulum • Trivial cases & equilibrium states • MATLAB models The Elastic Problem (Simple Harmonic Motion) 푑2푥 푑2푥 푘 • 퐹 = 푚 = −푘푥 = − 푥 푛푒푡 푑푡2 푑푡2 푚 • Solve this differential equation to find 푥 푡 = 푐1 cos 휔푡 + 푐2 sin 휔푡 = 퐴푐표푠(휔푡 − 휑) • With velocity and acceleration 푣 푡 = −퐴휔 sin 휔푡 + 휑 푎 푡 = −퐴휔2cos(휔푡 + 휑) • Total energy of the system 퐸 = 퐾 푡 + 푈 푡 1 1 1 = 푚푣푡2 + 푘푥2 = 푘퐴2 2 2 2 The Pendulum Problem (with some assumptions) • With position vector of point mass 푥 = 푙 푠푖푛휃푖 − 푐표푠휃푗 , define 푟 such that 푥 = 푙푟 and 휃 = 푐표푠휃푖 + 푠푖푛휃푗 • Find the first and second derivatives of the position vector: 푑푥 푑휃 = 푙 휃 푑푡 푑푡 2 푑2푥 푑2휃 푑휃 = 푙 휃 − 푙 푟 푑푡2 푑푡2 푑푡 • From Newton’s Law, (neglecting frictional force) 푑2푥 푚 = 퐹 + 퐹 푑푡2 푔 푡 The Pendulum Problem (with some assumptions) Defining force of gravity as 퐹푔 = −푚푔푗 = 푚푔푐표푠휃푟 − 푚푔푠푖푛휃휃 and tension of the string as 퐹푡 = −푇푟 : 2 푑휃 −푚푙 = 푚푔푐표푠휃 − 푇 푑푡 푑2휃 푚푙 = −푚푔푠푖푛휃 푑푡2 Define 휔0 = 푔/푙 to find the solution: 푑2휃 푔 = − 푠푖푛휃 = −휔2푠푖푛휃 푑푡2 푙 0 Derivation of Equations of Motion • m = pendulum mass • mspring = spring mass • l = unstreatched spring length • k = spring constant • g = acceleration due to gravity • Ft = pre-tension of spring 푚푔−퐹 • r = static spring stretch, 푟 = 푡 s 푠 푘 • rd = dynamic spring stretch • r = total spring stretch 푟푠 + 푟푑 Derivation of Equations of Motion -
Quantum Mechanics and Relativity): 21St Century Analysis
Noname manuscript No. (will be inserted by the editor) Joule's 19th Century Energy Conservation Meta-Law and the 20th Century Physics (Quantum Mechanics and Relativity): 21st Century Analysis Vladik Kreinovich · Olga Kosheleva Received: December 22, 2019 / Accepted: date Abstract Joule's Energy Conservation Law was the first \meta-law": a gen- eral principle that all physical equations must satisfy. It has led to many important and useful physical discoveries. However, a recent analysis seems to indicate that this meta-law is inconsistent with other principles { such as the existence of free will. We show that this conclusion about inconsistency is based on a seemingly reasonable { but simplified { analysis of the situation. We also show that a more detailed mathematical and physical analysis of the situation reveals that not only Joule's principle remains true { it is actually strengthened: it is no longer a principle that all physical theories should satisfy { it is a principle that all physical theories do satisfy. Keywords Joule · Energy Conservation Law · Free will · General Relativity · Planck's constant 1 Introduction Joule's Energy Conservation Law: historically the first meta-law. Throughout the centuries, physicists have been trying to come up with equa- tions and laws that describe different physical phenomenon. Before Joule, how- ever, there were no general principles that restricted such equations. James Joule showed, in [13{15], that different physical phenomena are inter-related, and that there is a general principle covering all the phenom- This work was supported in part by the US National Science Foundation grants 1623190 (A Model of Change for Preparing a New Generation for Professional Practice in Computer Science) and HRD-1242122 (Cyber-ShARE Center of Excellence). -
Noether's Theorems and Gauge Symmetries
Noether’s Theorems and Gauge Symmetries Katherine Brading St. Hugh’s College, Oxford, OX2 6LE [email protected] and Harvey R. Brown Sub-faculty of Philosophy, University of Oxford, 10 Merton Street, Oxford OX1 4JJ [email protected] August 2000 Consideration of the Noether variational problem for any theory whose action is invariant under global and/or local gauge transformations leads to three distinct the- orems. These include the familiar Noether theorem, but also two equally important but much less well-known results. We present, in a general form, all the main results relating to the Noether variational problem for gauge theories, and we show the rela- tionships between them. These results hold for both Abelian and non-Abelian gauge theories. 1 Introduction There is widespread confusion over the role of Noether’s theorem in the case of local gauge symmetries,1 as pointed out in this journal by Karatas and Kowalski (1990), and Al-Kuwari and Taha (1991).2 In our opinion, the main reason for the confusion is failure to appreciate that Noether offered two theorems in her 1918 work. One theorem applies to symmetries associated with finite dimensional arXiv:hep-th/0009058v1 8 Sep 2000 Lie groups (global symmetries), and the other to symmetries associated with infinite dimensional Lie groups (local symmetries); the latter theorem has been widely forgotten. Knowledge of Noether’s ‘second theorem’ helps to clarify the significance of the results offered by Al-Kuwari and Taha for local gauge sym- metries, along with other important and related work such as that of Bergmann (1949), Trautman (1962), Utiyama (1956, 1959), and Weyl (1918, 1928/9). -
Measuring Earth's Gravitational Constant with a Pendulum
Measuring Earth’s Gravitational Constant with a Pendulum Philippe Lewalle, Tony Dimino PHY 141 Lab TA, Fall 2014, Prof. Frank Wolfs University of Rochester November 30, 2014 Abstract In this lab we aim to calculate Earth’s gravitational constant by measuring the period of a pendulum. We obtain a value of 9.79 ± 0.02m/s2. This measurement agrees with the accepted value of g = 9.81m/s2 to within the precision limits of our procedure. Limitations of the techniques and assumptions used to calculate these values are discussed. The pedagogical context of this example report for PHY 141 is also discussed in the final remarks. 1 Theory The gravitational acceleration g near the surface of the Earth is known to be approximately constant, disregarding small effects due to geological variations and altitude shifts. We aim to measure the value of that acceleration in our lab, by observing the motion of a pendulum, whose motion depends both on g and the length L of the pendulum. It is a well known result that a pendulum consisting of a point mass and attached to a massless rod of length L obeys the relationship shown in eq. (1), d2θ g = − sin θ, (1) dt2 L where θ is the angle from the vertical, as showng in Fig. 1. For small displacements (ie small θ), we make a small angle approximation such that sin θ ≈ θ, which yields eq. (2). d2θ g = − θ (2) dt2 L Eq. (2) admits sinusoidal solutions with an angular frequency ω. We relate this to the period T of oscillation, to obtain an expression for g in terms of the period and length of the pendulum, shown in eq. -
Law of Conversation of Energy
Law of Conservation of Mass: "In any kind of physical or chemical process, mass is neither created nor destroyed - the mass before the process equals the mass after the process." - the total mass of the system does not change, the total mass of the products of a chemical reaction is always the same as the total mass of the original materials. "Physics for scientists and engineers," 4th edition, Vol.1, Raymond A. Serway, Saunders College Publishing, 1996. Ex. 1) When wood burns, mass seems to disappear because some of the products of reaction are gases; if the mass of the original wood is added to the mass of the oxygen that combined with it and if the mass of the resulting ash is added to the mass o the gaseous products, the two sums will turn out exactly equal. 2) Iron increases in weight on rusting because it combines with gases from the air, and the increase in weight is exactly equal to the weight of gas consumed. Out of thousands of reactions that have been tested with accurate chemical balances, no deviation from the law has ever been found. Law of Conversation of Energy: The total energy of a closed system is constant. Matter is neither created nor destroyed – total mass of reactants equals total mass of products You can calculate the change of temp by simply understanding that energy and the mass is conserved - it means that we added the two heat quantities together we can calculate the change of temperature by using the law or measure change of temp and show the conservation of energy E1 + E2 = E3 -> E(universe) = E(System) + E(Surroundings) M1 + M2 = M3 Is T1 + T2 = unknown (No, no law of conservation of temperature, so we have to use the concept of conservation of energy) Total amount of thermal energy in beaker of water in absolute terms as opposed to differential terms (reference point is 0 degrees Kelvin) Knowns: M1, M2, T1, T2 (Kelvin) When add the two together, want to know what T3 and M3 are going to be. -
Ballistic Pendulum
PH 1113: Ballistic Pendulum Ballistic Pendulum Objective The purpose of this experiment1 is to determine the muzzle velocity of a projectile launcher, using the conservation of momentum and the conservation of energy (where applicable). Materials 1. 1-meter stick 4. Projectile (metal ball) 2. 30-cm ruler 5. Triple-beam balance 3. Ballistic pendulum machine Introduction The ballistic pendulum is a classic method for determining the velocity of a projectile; origi- nally, it was used to determine the muzzle velocity of firearms. It is also a good demonstration of many basic principles of physics. In ballistic pendula experiments a projectile (in our case a ball) is fired into a stationary, freely hanging pendulum, which swings up by a measured amount after being impacted by the projectile. From that measured angle and from the length of the pendulum, you can determine the height reached by the center of mass of the pendulum; then you can calculate its gravitational potential energy. We know that mechanical energy (ME) is conserved, so we know that the gravitational potential energy at the maximum height must be equal to the kinetic energy of the pendulum at the bottom of the swing, just after the ball collides with the pendulum. In symbolic terms, MEi = MEf ; (1) where ME = PE + KE. So, 0 0 ¨¨* ¨¨* ¨PEi + KEi = PEf + ¨KE¨f (2) 1Some of the text of this manual was taken from the Pasco Ballistic Pendulum/Projectile Launcher Instruction Manual. 1 Mississippi State University Department of Physics and Astronomy You cannot, however, equate the kinetic energy of the pendulum after the collision with the kinetic energy of the ball before the swing, because the collision between ball and pendulum is inelastic, and kinetic energy is not conserved in inelastic collisions. -
Oil and Gas Conservation Law in Review
The Pennsylvania Oil and Gas Conservation Law: A Summary of the Statutory Provisions 58 P.S. §§ 401-419 (March 2009) Prepared by Anna M. Clovis, Research Assistant Under the Supervision of Ross H. Pifer, J.D., LL.M., Director The Agricultural Law Resource and Reference Center Penn State Dickinson School of Law http://www.dsl.psu.edu/centers/aglaw.cfm The Oil and Gas Conservation Law (OGC Law) is one of the primary laws that regulate the extraction of natural gas in Pennsylvania. The OGC Law has been summarized in a section- by-section manner in this research publication, which provides an overview of the issues regulated by the OGC Law. To obtain detailed information on the individual statutory sections, the full text of the OGC Law should be reviewed. Declaration of Policy The OGC Law reflects a policy “to foster, encourage, and promote the development, production, and utilization” of Pennsylvania’s oil and natural gas resources. Development activities should occur in a manner to prevent the waste of oil and natural gas. Oil and natural gas operations should be regulated to ensure that “the Commonwealth shall realize and enjoy the maximum benefit of these natural resources.” Since strata above the Onondaga horizon have been extensively developed since 1850, it would be impractical to include shallow wells within the regulations of the OGC Law. Section 1: Short Title (58 P.S. § 401) This statute shall be known as the “Oil and Gas Conservation Law.” Section 2: Definitions (58 P.S. § 402) This section provides statutory definitions for various oil and gas terms used in the OGC Law. -
Ballistic Pendulum March 2021 Lancaster/Basnet/Brown
Ballistic Pendulum March 2021 Lancaster/Basnet/Brown 1 Introduction This lab simulation explores the concept of conservation of energy by way of a ballistic pendulum and a projectile. 1.1 Tools This lab requires the use of the Google Chrome browser. Make certain it is installed on your computer. Navigate to http://physics.bu.edu/~duffy/HTML5/ballistic_pendulum.html to use the simulation. Intall the following Google Chrome extensions: Measure-it and Web Paint. They can be found at: https://chrome.google.com/webstore/detail/measure-it/jocbgkoackihphodedlefohapackjmna? hl=en https://chrome.google.com/webstore/detail/web-paint/emeokgokialpjadjaoeiplmnkjoaegng? hl=en. 1.2 Relevant Equations Kinetic energy: 1 K = mv2 (1) 2 Gravitational potential energy: U = mgh (2) Total energy: 1 E = K + U = mv2 + mgh (3) T otal 2 The velocity of the bullet-pendulum system immediately after the collision is: mb v = vb( ) (4) mb + M Where mb and vb are the mass and initial velocity of the bullet, and M is the mass of the ball hanging at the end of the pendulum. The kinetic energy of the bullet-pendulum system immediately after the collision is: 2 2 1 mb 2 2 1 mb vb K = (mb + M)( ) vb = (5) 2 mb + M 2 (mb + M) 2 Procedure Note: This simulation moves fast. For this reason, we'll take data using successive presses of the "step" button. Another note: For the purposes of this lab, assume that the initial gravitational potential of the pendulum is 0. 1 Ballistic Pendulum March 2021 Lancaster/Basnet/Brown 2.1 Part I: Initial Measurements 1. -
Application of Axiomatic Formal Theory to the Abraham--Minkowski
Application of axiomatic formal theory to the Abraham{Minkowski controversy Michael E. Crenshaw∗ Charles M. Bowden Research Laboratory, US Army Combat Capabilities Development Command (DEVCOM) - Aviation and Missile Center, Redstone Arsenal, AL 35898, USA (Dated: August 23, 2019) A transparent linear dielectric in free space that is illuminated by a finite quasimonochromatic field is a thermodynamically closed system. The energy{momentum tensor that is derived from Maxwellian continuum electrodynamics for this closed system is inconsistent with conservation of momentum; that is the foundational issue of the century-old Abraham{Minkowski controversy. The long-standing resolution of the Abraham{Minkowski controversy is to view continuum electrodynam- ics as a subsystem and write the total energy{momentum tensor as the sum of an electromagnetic energy{momentum tensor and a phenomenological material energy{momentum tensor. We prove that if we add a material energy{momentum tensor to the electromagnetic energy{momentum ten- sor, in the prescribed manner, then the total energy, the total linear momentum, and the total angular momentum are constant in time, but other aspects of the conservation laws are violated. Specifically, the four-divergence of the total (electromagnetic plus material) energy{momentum ten- sor is self-inconsistent and violates Poynting's theorem. Then, the widely accepted resolution of the Abraham{Minkowski dilemma is proven to be manifestly false. The fundamental physical principles of electrodynamics, conservation laws, and special relativity are intrinsic to the vacuum; the ex- tant dielectric versions of physical principles are non-fundamental extrapolations from the vacuum theory. Because the resolution of the Abraham{Minkowski momentum controversy is proven false, the extant theoretical treatments of macroscopic continuum electrodynamics, dielectric special rel- ativity, and energy{momentum conservation in a simple linear dielectric are mutually inconsistent for macroscopic fields in matter. -
The Dawn of Fluid Dynamics a Discipline Between Science and Technology
Titelei Eckert 11.04.2007 14:04 Uhr Seite 3 Michael Eckert The Dawn of Fluid Dynamics A Discipline between Science and Technology WILEY-VCH Verlag GmbH & Co. KGaA Titelei Eckert 11.04.2007 14:04 Uhr Seite 1 Michael Eckert The Dawn of Fluid Dynamics A Discipline between Science and Technology Titelei Eckert 11.04.2007 14:04 Uhr Seite 2 Related Titles R. Ansorge Mathematical Models of Fluiddynamics Modelling, Theory, Basic Numerical Facts - An Introduction 187 pages with 30 figures 2003 Hardcover ISBN 3-527-40397-3 J. Renn (ed.) Albert Einstein - Chief Engineer of the Universe 100 Authors for Einstein. Essays approx. 480 pages 2005 Hardcover ISBN 3-527-40574-7 D. Brian Einstein - A Life 526 pages 1996 Softcover ISBN 0-471-19362-3 Titelei Eckert 11.04.2007 14:04 Uhr Seite 3 Michael Eckert The Dawn of Fluid Dynamics A Discipline between Science and Technology WILEY-VCH Verlag GmbH & Co. KGaA Titelei Eckert 11.04.2007 14:04 Uhr Seite 4 The author of this book All books published by Wiley-VCH are carefully produced. Nevertheless, authors, editors, and Dr. Michael Eckert publisher do not warrant the information Deutsches Museum München contained in these books, including this book, to email: [email protected] be free of errors. Readers are advised to keep in mind that statements, data, illustrations, proce- Cover illustration dural details or other items may inadvertently be “Wake downstream of a thin plate soaked in a inaccurate. water flow” by Henri Werlé, with kind permission from ONERA, http://www.onera.fr Library of Congress Card No.: applied for British Library Cataloging-in-Publication Data: A catalogue record for this book is available from the British Library.