DOCSLIB.ORG

Systems Approach to the Concept of Environment1' 2

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Systems Approach to the Concept of Environment1' 2 Copyright © 1978 Ohio Acad. Sci. 0030-0950/78/0004-0206S2.00/0 SYSTEMS APPROACH TO THE CONCEPT OF ENVIRONMENT1' 2 BERNARD C. PATTEN, Department of Zoology and Institute of Ecology, University of Georgia, Athens, GA 30602 Abstract. A systems theory of environment formulates causal interactions between things, including organisms, and their environments in terms of four system theoretical abstract objects. Creaons receive stimuli and implicitly create input environments. Genons react to received causes and generate potential output environments as effects. A holon represents the combined input-output model of an entity consisting of a creaon and a genon. An environ is a creaon and its corresponding input environment, or a genon and its related output environment. The theory is presented in terms of three propositions that: (1) recognize two distinct environments (input and output) asso- ciated with things, (2) establish things and their environments as units (environs) to be taken together, and (3) partition systems into input and output environs associated with intrasystem creaons and genons, respectively. OHIO J. SCI. 78(4): 206, 1978 Ecology is the biological science of en- organism, loose usage frequently extends vironment. It considers environment as the concept from individuals to groups a derivative of physiology in the sense {our environment), or suggests something that environment contains resources to absolute (the environment). The dic- be mobilized by organisms, and condi- tionary defines environment variously as: tions of life under which this mobilization "the surrounding conditions, influences or must occur. The resource in least sup- forces that influence or modify; the whole ply at any given time is rate limiting (law complex of climatic, edaphic and biotic of the minimum), as is the factor, such as factors that act upon an organism or an temperature, in greatest extreme (law of ecological community and ultimately de- tolerance). Thus, the organism is seen termine its form and survival; the aggre- by ecology to inhabit a physiological life gate of social and cultural conditions that space bounded by conservative and non- influence the life of an individual or com- conservative elements of its environment munity," (Merriam-Webster 1971). The —resources and factors, respectively. significant features of environment in The nature and composition of this life ordinary usage are that some defined sub- space varies according to the character ject (individual or group) is immersed in of the larger system of which the organ- or surrounded by it, and influenced by ism is seen as a part. Population aspects it through a causal relationship. This of environment encompass the intra- causality, as developed below, is the specific reproductive, genetic, demo- basis for the present attempt to express graphic and social worlds of the organ- environment in terms of system theory, ism. A community aspect refers to in- which is the purpose of this paper. terspecific biotic associations. The eco- system aspect takes into account all fea- SYSTEMS DEFINITIONS tures of the organism's biotic and abiotic Systems ecology is a branch of ecology interactions. that applies systems thinking and meth- ods to ecological problems. Several def- Although the strict ecological idea of initions of basic system concepts are use- environment is based on the individual ful in prospect of a systems approach to defining environment. A system is a 1Manuscript received January 19, 1977 and in revised form June 15, 1978 (#77-6). partially interconnected (interacting or 2University of Georgia Contributions in Sys- causally joined) set of components. In- tems Ecology, No. 41. teractions may be mediated by energy- 206 Ohio J. Sci. EIA-SYSTEMS APPROACH 207 matter through transactions, or by infor- an organism. Non-environment consists mation through communications. Trans- of all phenomena (indirect, historical and actions and communications correspond, organism-caused) which never enter into respectively, to transfers of conservative a direct environmental relation with the resources and nonconservative factors in organism. the physiological account of environment Mason and Langenheim (1957) as- described above. serted, "the environment of any organ- In a hierarchical model of nature, any ism is the class ... of those phenomena given system can usefully be abstracted that enter a reaction system of the organ- as three discrete levels separated out of a ism or otherwise directly impinge upon it hierarchical continuum: system, subsys- to affect its mode of life at any time tem and supersystem. Subsystems are throughout its life cycle as ordered by the components of the systems. Supersys- demands of the ontogeny of the organism tems are composed of systems. Koestler's or as ordered by any other condition . (1967) term "holon" for a hierarchical that alters its environmental demands." system can be used to refer to any of Only direct factors were considered part these three levels of organization, accord- of environment. "[Indirect and histori- ing to the frame of reference. cal] factors both function to condition a A system is closed if it does not interact phenomenon ... to which an organism with another system, and open if it re- then reacts. Important as this is to the ceives causes from or generates effects to ecosystem the only [organism] reaction another system. A system boundary ... is to an already conditioned phe- provides the interface with other systems nomenon. The state of the phenomenon and is defined by specifying its component prior to its conditioning is outside the set. Input is any movement of energy- scope of operational . and . po- matter or information from supersystem tential environment. This may seem to system, and output is any similar to rest upon trivial distinctions, but we movement across the system boundary in are convinced that this is the precise the opposite direction. boundary between clarity and confusion in the problems of the environment." ECOLOGICAL CONCEPTS OF Thus, chains and networks of historical ENVIRONMENT causation, which condition direct factors, Environment as a concept has not been are excluded from Mason and Langen- treated very seriously in ecological litera- heim's (1957) concept of environment: ture and only a few explicit works are "... we must reject the implication that available. Mason and Langenheim (1957) . [causal] chains constitute a unitary defined environmental phenomena as those event playing a significant role in the en- that have or may have an operational re- vironmental relation even though the lation with any organism. The environ- steps are very important to the ecosys- mental relation of an organism is the sum tem. There is also a philosophical of empirical relations between the en- reason for removing indirect factors from vironmental phenomena and any indi- the concept of environment. To intro- vidual organism. The operational en- duce indirect factors into causal relations vironment of an organism consists of those within the environment is to introduce an instantaneous environmental phenomena infinite regress into the system of expla- that actually enter a relation with an or- nation. Every cause has in turn itself ganism; the concept applies to specific in- a cause which becomes an indirect cause dividual organisms. Space and time of the most recent effect. The regress is frames of the operational environment toward the limbo of ultimate cause along are determined by the organism. The an infinitely reticulating path; for this life span of the organism corresponds to we have neither finite description nor the existence time of its operational en- finite explanation. To include such vironment. Potential environment con- relations in environment is to confuse en- sists of the set of environmental phenom- vironment with its history." ena that may enter into an environmental A systems ecology concept of environ- relation at some point in the ontogeny of ment must take issue with the Mason and 208 BERNARD C. PATTEN Vol. 78 Langenehim theory. The whole thrust causes as well, so long as their eventual of a systems understanding of nature is influences can be propagated to a sub- to reconstruct the main patterns of causa- ject, such as an organism, during its tion in models. Within the confines of a existence interval. Systems ecology mod- finite model forming a whole from inter- els that represent complex intrasystem connected parts, an expanded concept of webs of direct and indirect causation environment of the parts is possible, make it possible to implement such an which includes both direct and indirect expanded concept of environment. A factors. The intrasystem causal net- formal approach to such implementation work is never an unknown infinite regress, is described below. but is explicit to the model boundary which constitutes the limit of finite de- HOLONS scription and explanation which were General systems theory defines a sys- lacking in Mason and Langenheim's time. tem to be a partially interconnected set of While the conditioning of direct causes by objects, then proceeds to describe the ob- indirect effects may be temporally ante- jects and various aspects of their inter- cedent, ecosystems and their models are active coupling. Formal details differ persistent or recurrent organizations so with the specific theory, but most general that historical patterns of causation are systems objects have in common that in relevant, with perhaps small corrections some sense they perform
Load more

Recommended publications
  • Outline of Physical Science
    Outline of physical science “Physical Science” redirects here. It is not to be confused • Astronomy – study of celestial objects (such as stars, with Physics. galaxies, planets, moons, asteroids, comets and neb- ulae), the physics, chemistry, and evolution of such Physical science is a branch of natural science that stud- objects, and phenomena that originate outside the atmosphere of Earth, including supernovae explo- ies non-living systems, in contrast to life science. It in turn has many branches, each referred to as a “physical sions, gamma ray bursts, and cosmic microwave background radiation. science”, together called the “physical sciences”. How- ever, the term “physical” creates an unintended, some- • Branches of astronomy what arbitrary distinction, since many branches of physi- cal science also study biological phenomena and branches • Chemistry – studies the composition, structure, of chemistry such as organic chemistry. properties and change of matter.[8][9] In this realm, chemistry deals with such topics as the properties of individual atoms, the manner in which atoms form 1 What is physical science? chemical bonds in the formation of compounds, the interactions of substances through intermolecular forces to give matter its general properties, and the Physical science can be described as all of the following: interactions between substances through chemical reactions to form different substances. • A branch of science (a systematic enterprise that builds and organizes knowledge in the form of • Branches of chemistry testable explanations and predictions about the • universe).[1][2][3] Earth science – all-embracing term referring to the fields of science dealing with planet Earth. Earth • A branch of natural science – natural science science is the study of how the natural environ- is a major branch of science that tries to ex- ment (ecosphere or Earth system) works and how it plain and predict nature’s phenomena, based evolved to its current state.
    [Show full text]
  • Thermodynamic Processes: the Limits of Possible
    Thermodynamic Processes: The Limits of Possible Thermodynamics put severe restrictions on what processes involving a change of the thermodynamic state of a system (U,V,N,…) are possible. In a quasi-static process system moves from one equilibrium state to another via a series of other equilibrium states . All quasi-static processes fall into two main classes: reversible and irreversible processes . Processes with decreasing total entropy of a thermodynamic system and its environment are prohibited by Postulate II Notes Graphic representation of a single thermodynamic system Phase space of extensive coordinates The fundamental relation S(1) =S(U (1) , X (1) ) of a thermodynamic system defines a hypersurface in the coordinate space S(1) S(1) U(1) U(1) X(1) X(1) S(1) – entropy of system 1 (1) (1) (1) (1) (1) U – energy of system 1 X = V , N 1 , …N m – coordinates of system 1 Notes Graphic representation of a composite thermodynamic system Phase space of extensive coordinates The fundamental relation of a composite thermodynamic system S = S (1) (U (1 ), X (1) ) + S (2) (U-U(1) ,X (2) ) (system 1 and system 2). defines a hyper-surface in the coordinate space of the composite system S(1+2) S(1+2) U (1,2) X = V, N 1, …N m – coordinates U of subsystems (1 and 2) X(1,2) (1,2) S – entropy of a composite system X U – energy of a composite system Notes Irreversible and reversible processes If we change constraints on some of the composite system coordinates, (e.g.
    [Show full text]
  • Designing a Physics Learning Environment: a Holistic Approach
    Designing a physics learning environment: A holistic approach David T. Brookes and Yuhfen Lin Department of Physics, Florida International University, 11200 SW 8th St, Miami, 33199 Abstract. Physics students enter our classroom with significant learning experiences and learning goals that are just as important as their prior knowledge. Consequently, they have expectations about how they should be taught. The instructor enters the same classroom and presents the students with materials and assessments that he/she believes reflect his/her learning goals for the students. When students encounter a reformed physics class, there is often a “misalignment” between students’ perceptions, and learning goals the instructor designed for the students. We want to propose that alignment can be achieved in a reformed physics class by taking a holistic view of the classroom. In other words, it is not just about teaching physics, but a problem of social engineering. We will discuss how we applied this social engineering idea on multiple scales (individual students, groups, and the whole class) to achieve alignment between students’ expectations and the instructor’s learning goals. Keywords: Physics education, learning environment, learning goals, attitudes, motivation PACS: 01.40.Fk, 01.40.Ha INTRODUCTION his/her students. 3) We paid careful attention to designing the learning environment to maximize Many Research-Based Instructional Strategies effective communication and interaction between (RBIS) in physics are initially successful when students. implemented by their developers, but other adopters sometimes struggle to achieve the same level of THEORY AND COURSE SETTING success. Firstly, students are resistant to reform [1]. Secondly, when physics instructors try implementing Interacting System Model one or more RBIS, they quickly discover that they do not work as advertised [2].
    [Show full text]
  • Week 11: Chapter 11
    The Vector Product There are instances where the product of two Week 11: Chapter 11 vectors is another vector Earlier we saw where the product of two vectors Angular Momentum was a scalar This was called the dot product The vector product of two vectors is also called the cross product The Vector Product and Torque The Vector Product Defined The torque vector lies in a Given two vectors, A and B direction perpendicular to the plane formed by the The vector (cross) product of A and B is position vector and the force vector defined as a third vector, CAB Fr C is read as “A cross B” The torque is the vector (or cross) product of the The magnitude of vector C is AB sin position vector and the is the angle between A and B force vector More About the Vector Product Properties of the Vector Product The quantity AB sin is The vector product is not commutative. The equal to the area of the order in which the vectors are multiplied is parallelogram formed important by A and B To account for order, remember The direction of C is A BBA perpendicular to the plane formed by A and B If A is parallel to B ( = 0o or 180o), then The best way to A B 0 determine this direction is to use the right-hand Therefore A A 0 rule 1 More Properties of the Vector Final Properties of the Vector Product Product If A is perpendicular to B , then ABAB The derivative of the cross product with The vector product obeys the distributive law respect to some variable such as t is ddA dB ABCABAC x ( + ) = x + x AB
    [Show full text]
  • The Influence of Thermodynamic Ideas on Ecological Economics: an Interdisciplinary Critique
    Sustainability 2009, 1, 1195-1225; doi:10.3390/su1041195 OPEN ACCESS sustainability ISSN 2071-1050 www.mdpi.com/journal/sustainability Article The Influence of Thermodynamic Ideas on Ecological Economics: An Interdisciplinary Critique Geoffrey P. Hammond 1,2,* and Adrian B. Winnett 1,3 1 Institute for Sustainable Energy & the Environment (I•SEE), University of Bath, Bath, BA2 7AY, UK 2 Department of Mechanical Engineering, University of Bath, Bath, BA2 7AY, UK 3 Department of Economics, University of Bath, Bath, BA2 7AY, UK; E-Mail: [email protected] * Author to whom correspondence should be addressed; E-Mail: [email protected]; Tel.: +44-12-2538-6168; Fax: +44-12-2538-6928. Received: 10 October 2009 / Accepted: 24 November 2009 / Published: 1 December 2009 Abstract: The influence of thermodynamics on the emerging transdisciplinary field of ‗ecological economics‘ is critically reviewed from an interdisciplinary perspective. It is viewed through the lens provided by the ‗bioeconomist‘ Nicholas Georgescu-Roegen (1906–1994) and his advocacy of ‗the Entropy Law‘ as a determinant of economic scarcity. It is argued that exergy is a more easily understood thermodynamic property than is entropy to represent irreversibilities in complex systems, and that the behaviour of energy and matter are not equally mirrored by thermodynamic laws. Thermodynamic insights as typically employed in ecological economics are simply analogues or metaphors of reality. They should therefore be empirically tested against the real world. Keywords: thermodynamic analysis; energy; entropy; exergy; ecological economics; environmental economics; exergoeconomics; complexity; natural capital; sustainability Sustainability 2009, 1 1196 ―A theory is the more impressive, the greater the simplicity of its premises is, the more different kinds of things it relates, and the more extended is its area of applicability.
    [Show full text]
  • Chapter 10 Energy and Work
    Chapter 10 Energy and Work Lecture Presentation Chapter 10 Energy and Work Chapter Goal: To introduce the concept of energy and to learn a new problem-solving strategy based on conservation of energy. © 2015 Pearson Education, Inc. © 2015 Pearson Education, Inc. Slide 10-2 Chapter 10 Preview Chapter 10 Preview Looking Ahead: Forms of Energy Looking Ahead: Work and Energy • This dolphin has lots of kinetic energy as it leaves the • As the band is stretched, energy is transferred to it as water. At its highest point its energy is mostly potential work . This energy is then transformed into kinetic energy energy . of the rock. • You’ll learn about several of the most important forms of • You’ll learn how to calculate the work done by a force, energy—kinetic, potential, and thermal. and how this work is related to the change in a system’s energy. © 2015 Pearson Education, Inc. Slide 10-3 © 2015 Pearson Education, Inc. Slide 10-4 Chapter 10 Preview Chapter 10 Preview Looking Ahead: Conservation of Energy Looking Ahead • As they slide, their potential energy decreases and their kinetic energy increases, but their total energy is unchanged: It is conserved . • How fast will they be moving when they reach the bottom? Text: p. 283 You’ll use a new before-and-after analysis to find out. © 2015 Pearson Education, Inc. Slide 10-5 © 2015 Pearson Education, Inc. Slide 10-6 Chapter 10 Preview Chapter 10 Preview Looking Back: Motion with Constant Acceleration Stop to Think In Chapter 2 you learned how to describe the motion of a A car pulls away from a stop sign with a constant particle that has a constant acceleration.
    [Show full text]
  • Sustainability and the Viable Systems Approach: Opportunities and Issues for the Governance of the Territory
    sustainability Article Sustainability and the Viable Systems Approach: Opportunities and Issues for the Governance of the Territory Sergio Barile, Bernardino Quattrociocchi, Mario Calabrese ID and Francesca Iandolo * ID Department of Management, Sapienza University, Rome 00161, Italy; [email protected] (S.B.); [email protected] (B.Q.); [email protected] (M.C.) * Correspondence: [email protected] Received: 22 January 2018; Accepted: 3 March 2018; Published: 13 March 2018 Abstract: The aim of this paper is to propose an approach for representing the territory as a dynamic system of intersubjective relationships that is able to guarantee not only the efficiency of the processes within organizations, but also effective results in the general context and a sustainable impact on the broader environment. This contribution is developed on the basis of the viable systems approach (vSa), which is intended as a theoretical framework for the analysis of social phenomena as well as for orienting government processes. Using this theoretical framework, the proposed approach leads to the representation of the territory as a viable system that is capable of surviving in its own context by creating value for the other entities of the context (public groups of governments, communities, investors, natural environment, future generations, non-human species), thus defining the essential conditions for a sustainable equilibrium. The consideration that social phenomena have to be analyzed by taking into account the different relations and interactions that orient the behavior of individuals and, as a consequence, their main collective manifestations, i.e., organizations, underlines the importance of shifting from a traditional reductionist approach to a systemic approach.
    [Show full text]
  • Developing a Viable Model of the Enterprise Taking Into Consideration
    ISSN: 0798-1015 Vol. 41 (29) 2020 • Art. 6 Recibido/Received: 19/03/2020 • Aprobado/Approved:23/07/2020 • Publicado/Published: 06/08/2020 Developing a viable model of the enterprise taking into consideration the impact of the environment: studying economic and legal impact factors Formación de un modelo sostenible de la empresa teniendo en cuenta el impacto del ambiente: un estudio de los factores económicos y legales FEDOTOVA, Iryna V.1, AZARENKOV, Grygorii F.2, TYMOSHEVSKA, Iryna P.3, PYSARCHUK, Oksana V.4, BOCHAROVA, Nadiia А.5 Abstract The article is devoted to the actual problem of ensuring the enterprises viability on the basis of the methodical apparatus of cybernetic modeling of viable systems. On the basis of structural-level and systematic approaches, the basic levels and structure of a viable enterprise system are determined. Taking into account the influence of external and internal factors of environment the multilevel spherical model of ensuring the viability of the enterprise is proposed. key words: enterprise viability, viable system model, recursive structure, spheres model Resumen El artículo está dedicado a la cuestión apremiante de garantizar la viabilidad de las empresas basándose en el aparato metódico de la simulación cibernética de sistemas viables. Utilizando el enfoque sistemático, escalonado y estructural, se determinan los niveles básicos y la estructura de un sistema viable de la empresa. Se propone un modelo esférico multinivel para garantizar la viabilidad de la empresa, teniendo en cuenta la influencia de los factores del ambiente externo e interno. Palabras clave : viabilidad de la empresa, modelo del sistema viable, estructura recursiva, modelo de esferas 1 Ph.D.
    [Show full text]
  • Thermodynamics of Environment
    Journal ofMining and Metallurgy, 36 (1-2)B (2000) 93 - 110 Letters to Editor THERMODYNAMICS OF ENVIRONMENT v. M. Zhukovsky Chemistry Dept., Ural State University, 51 Lenin av., 620083, Ekaterinburg, Russia e-mail: [email protected] (Received 10 November 1999; accepted 10January 2000) Abstract A possibility of non-equilibrium thermodynamic application to analysis of systems like living organisms - environment were considered. The significance ofthe human com­ munity interaction and coexisting with the biosphere were discussed. V.I. Vernadsky (1863 - 1945) conception oftransformation the biosphere into noosphere was considered. Keywords: ecology, environment, thermodynamics, anthropogenic factor, biosphere, coevolution, noosphere. 1. Introduction The environmental problems actually have overgrown problems of local industrial company, town, city or region. The transboundary transfer of pollutants over countries and continents makes these problems very important for humanity taken as a whole. The term ecology (from Greek oikos = house, residence, and logos = word, teaching) was introduced into scientific usage by E. Haeckel in 1866. J.Min.Met. 36 (1-2)B 2000 93 Letters to Editor Ecology was regarded as a part of biology, which studied an interaction of living organism and environment (dwelling place) (Fig. I). Modern concept of environment regards ecology as part of it. Interaction ~ EmriroJtllleuW field ----Interaction Fig. 1. The environmental field. The environment involves both nonliving physical and chemical com­ ponents (sunlight, heat, moisture, wind, oxygen, carbon dioxide, nutrients in atmosphere, hydrosphere, soil) and living biological components (geneti­ cally identical bodies, each and all objects of vegetable life and animals). The terms ecology (environmental science) and economics have a common basis. Modern term environmental study, in particular, involves study of Nature economy.
    [Show full text]
  • Optimal Classification Trees Dimitris Bertsimas & Jack Dunn
    Optimal classification trees Dimitris Bertsimas & Jack Dunn Machine Learning ISSN 0885-6125 Volume 106 Number 7 Mach Learn (2017) 106:1039-1082 DOI 10.1007/s10994-017-5633-9 1 23 Your article is protected by copyright and all rights are held exclusively by The Author(s). This e-offprint is for personal use only and shall not be self-archived in electronic repositories. If you wish to self-archive your article, please use the accepted manuscript version for posting on your own website. You may further deposit the accepted manuscript version in any repository, provided it is only made publicly available 12 months after official publication or later and provided acknowledgement is given to the original source of publication and a link is inserted to the published article on Springer's website. The link must be accompanied by the following text: "The final publication is available at link.springer.com”. 1 23 Author's personal copy Mach Learn (2017) 106:1039–1082 DOI 10.1007/s10994-017-5633-9 Optimal classification trees Dimitris Bertsimas1 Jack Dunn2 · Received: 17 September 2015 / Accepted: 3 March 2017 / Published online: 3 April 2017 ©TheAuthor(s)2017 Abstract State-of-the-art decision tree methods apply heuristics recursively to create each split in isolation, which may not capture well the underlying characteristics of the dataset. The optimal decision tree problem attempts to resolve this by creating the entire decision tree at once to achieve global optimality. In the last 25years, algorithmic advances in inte- ger optimization coupled with hardware improvements have resulted in an astonishing 800 billion factor speedup in mixed-integer optimization (MIO).
    [Show full text]
  • Morphology and Environment of Dwarf Galaxies in the Local Universe H
    Dark Galaxies and Lost Baryons Proceedings IAU Symposium No. 244, 2007 c 2008 International Astronomical Union J.I. Davies & M. J. Disney, eds. doi:10.1017/S1743921307014202 Morphology and Environment of Dwarf Galaxies in the Local Universe H. B. Ann1 1 Division of Science Education, Pusan National University, Busan, 609-735, Korea email: [email protected] Abstract. Analysis of dwarf galaxies in the local universe shows that dwarf irregular galaxies are its dominant populations and the majority of dwarf elliptical galaxies are likely to be located in the overdense regions, However, a significant fraction of blue dwarf ellipticals (dEblue)and peculiar dwarf ellipticals (dEpec are found to be located in the under-dense regions. Keywords. dwarf galaxies, morphology, environment 1. Introduction Understanding the formation mechanism of dwarf galaxies is central to the modern observational cosmology since they are the most abundant populations. Owing to their intrinsic faintness, there is no statistics on their distribution as well as their physical properties beyond the local group. However, thanks to the advent of SDSS it is now possible to analyze the statistics of dwarf galaxies in various environments. The purpose of the present study is to analyze the environment dependence of galaxy morphology using SDSS DR5 complemented by nearby galaxy catalogs for brighter galaxies. 2. Morphology of dwarf galaxies The dwarf elliptical galaxies were classified into dE, ‘dE,N’, dEpec, dE/Im, and dS0, based on Sandage & Binggeli (1984) scheme. We added blue dwarf ellipticals dEblue, which are known by blue colors owing to the global presence of young stellar populations, are known to be abundant in the nearby universe.
    [Show full text]
  • 7 Work, Energy, and Energy Resources
    CHAPTER 7 | WORK, ENERGY, AND ENERGY RESOURCES 221 7 WORK, ENERGY, AND ENERGY RESOURCES Figure 7.1 How many forms of energy can you identify in this photograph of a wind farm in Iowa? (credit: Jürgen from Sandesneben, Germany, Wikimedia Commons) Learning Objectives 7.1. Work: The Scientific Definition • Explain how an object must be displaced for a force on it to do work. • Explain how relative directions of force and displacement determine whether the work done is positive, negative, or zero. 7.2. Kinetic Energy and the Work-Energy Theorem • Explain work as a transfer of energy and net work as the work done by the net force. • Explain and apply the work-energy theorem. 7.3. Gravitational Potential Energy • Explain gravitational potential energy in terms of work done against gravity. • Show that the gravitational potential energy of an object of mass m at height h on Earth is given by PEg = mgh . • Show how knowledge of the potential energy as a function of position can be used to simplify calculations and explain physical phenomena. 7.4. Conservative Forces and Potential Energy • Define conservative force, potential energy, and mechanical energy. • Explain the potential energy of a spring in terms of its compression when Hooke’s law applies. • Use the work-energy theorem to show how having only conservative forces implies conservation of mechanical energy. 7.5. Nonconservative Forces • Define nonconservative forces and explain how they affect mechanical energy. • Show how the principle of conservation of energy can be applied by treating the conservative forces in terms of their potential energies and any nonconservative forces in terms of the work they do.
    [Show full text]