NAME OF UNIT: Energy and Momentum NAME OF UNIT Thermodynamics Components 3 weeks (weeks 12-14) 2 weeks (weeks 15-17) Unit Name Energy and Momentum Thermodynamics Introduction In the world today, objects are always colliding with other objects. Those collisions can be cars with cars, bowling balls with bowling pens, baseballs with bats, and people with people even molecules with molecules. The outcomes of these collisions always lend a level of fascination to the observer. The study of the collisions always includes the examination of the conservation law for momentum. This investigation is a natural progression following the study of forces. Physics words are in our everyday language and often have different or implied meanings that vary far from the physics definition. Energy and work are two such terms. Students struggle with the common usage of the terms and the physics definitions of the terms. Again, the term machine is a clearly specific and receives some exaggerations in our everyday language. The struggle with this study in the conflict in definitions more than the arithmetic operations. A little mental effort in identifying the right machine for a task can save lots of physical effort. From opening a can of paint to releasing a car stuck in the mud to sharpening a pencil, machines are part of everyday life. Short Descriptive Overview Generalizations/Enduring Understandings Momentum and Impulse are introduced as a rearrangement of Newton s second law. The study begins with a discussion of twoparticle collisions in closed and isolated systems in relation to the law of conservation of momentum. The final discussion includes explosions where the initial momentum is zero The concepts of energy and work are defined and then expanded to explain the operation of simple machines. Students will find that the terms energy and work have specific definitions that may be different from their use in everyday language. Machines are defined as devices that change either the direction of the force or multiply the output force or distance the force has to move. 1. Momentum and impulse are results of Newton s second law and contact forces. 2. Momentum and impulse describe the interaction of objects. 3. Newton s third law of motion can be related to the conservation of momentum. 1. Work and power describe how energy moves through the environment. The transfer of energy through the universe is the foundation of the study of physics. In this unit, the concept of stored energy and its transfer will be studied. Phase changes and temperature changes are found in the study of chemistry. In physics, these phenomena will be reviewed and then the transfer of this energy will be followed and quantified. Thermal energy provides the energy to keep you warm, to prepare and preserve food and to manufacture many of the objects you use on a daily basis. Thermal energy will be introduced, and then related to thermodynamics, the kinetic-molecular theory and temperature. The thermal energy as it relates to phase changes will be explored. Connections will be made with the first and second laws of thermodynamics, as well as their applications to heat engines, refrigerators and heat pumps. 1. The thermal energy of a body includes the kinetic and potential energy of the particles. 2. Temperature is different from thermal energy. 3. Specific heat is an identifying characteristic of matter. 4. The transfer of heat energy is governed by the law of conservation of energy. 5. The heats of fusion and vaporization are identifying 08/08/20115:28 PM 1
Concepts Guiding/Essential Questions 2. Relating force to work explains how machines make work easier by changing forces. 3. In physics, there are six simple machines and all other machines are combinations of these six. Momentum before and after an event Momentum of an object Impulse of an object Impulse equals the change in momentum Newton s third law for collisions Conservation of momentum for collisions. Conditions for the conservation of momentum Conservation of momentum for rockets Conservation of momentum in two dimensions using vector analysis Work and energy relationship Calculation of work done by a force The force doing work Work and power relationship Calculation of power Usefulness of simple machines Mechanical advantage in ideal and real machines Analysis of compound machines Compound machines in terms of simple machines. Efficiencies for simple and compound machines. 1. How does the concept of momentum relate to Newton s second law? 2. How does impulse relate to Newton s second law? 3. How does momentum describe the interaction of objects? 4. How does impulse describe the interaction of objects? 5. How does the law of conservation of momentum relate to Newton s third law of motion? 1. How is work related to power? 2. How does wok and power describe the movement of energy through the environment? 3. How does force relate to work? 4. Do all forces do work? 5. What are the six simple machines? 6. How do machines make work easier by changing force? 7. What is the difference between a simple machine and a compound machine? characteristics of matter. 6. The first and second laws of thermodynamics describe the transfer of thermal energy. 7. Entropy is related to the thermal energy of a material. 1. What kind of energy determines the amount of thermal energy? 2. What does temperature indicate regarding a quantity of matter? 3. How is the Q = mcδt applied to a specific material? 4. How does the law of conservation of energy apply to heat transfer? 5. How are the heats of fusion and vaporization measured and what do these values indicate about the materials? 6. What do the first and second laws of thermodynamics indicate regarding heat engines and motors? 7. How is work and energy related to the change in entropy? 08/08/20115:28 PM 2
Learning Targets Formative Assessment Summative Assessment TEKS Process The expansion of Newton s Second Law to momentum and impulse Conservation laws of Energy and Momentum Connection between force, work and energy The relationship between the internal energy of a system with the changes of work and heat on the system. The relationship of the laws of thermodynamics to the work and heat on a system Test on Momentum Test on energy, work and power Scientific Process Skills: (1) Physics. In Physics, students conduct laboratory and field investigations, use scientific methods during investigations, and make informed decisions using critical thinking and scientific problem solving. Students study a variety of topics that include: laws of motion; changes within physical systems and conservation of energy and momentum; forces; thermodynamics; characteristics and behavior of waves; and atomic, nuclear, and quantum physics. Students who successfully complete Physics will acquire factual knowledge within a conceptual framework, practice experimental design and interpretation, work collaboratively with colleagues, and develop critical thinking skills. (2) Nature of science. Science, as defined by the National Academy of Sciences, is the "use of evidence to construct testable explanations and predictions of natural phenomena, as well as the knowledge generated through this process." This vast body of changing and increasing knowledge is described by physical, mathematical, and conceptual models. Students should know that some questions are outside the realm of science because they deal with phenomena that are not scientifically testable. (3) Scientific inquiry. Scientific inquiry is the planned and deliberate investigation of the natural world. Scientific methods of investigation can be experimental, descriptive, or comparative. The method chosen should be appropriate to the question being asked. (4) Science and social ethics. Scientific decision making is a way of answering questions about the natural world. Students should be able to distinguish between scientific decision-making methods and ethical and social decisions that involve the application of scientific information. (5) Scientific systems. A system is a collection of cycles, structures, and processes that interact. All systems have basic properties that can be described in terms of space, time, energy, and matter. Change and constancy occur in systems as patterns and can be observed, measured, and modeled. These patterns help to make predictions that can be scientifically tested. Students should analyze a system in terms of its components and how these components relate to each other, to the whole, and to the external environment. (c) Knowledge and skills. (1) Scientific processes. The student conducts investigations, for at least 40% of instructional time, using safe, environmentally appropriate, and ethical practices. These investigations must involve actively obtaining and analyzing data with physical equipment, but may also involve experimentation in a simulated environment as well as field observations that extend beyond the classroom. The student is expected to: (A) demonstrate safe practices during laboratory and field investigations; and (B) demonstrate an understanding of the use and conservation of resources and the proper disposal or recycling of materials. (2) Scientific processes. The student uses a systematic approach to answer scientific laboratory and field investigative questions. The student is expected to: (A) know the definition of science and understand that it has limitations, as specified in subsection (b)(2) of this section; (B) know that scientific hypotheses are tentative and testable statements that must be capable of being supported or not supported by observational evidence. Hypotheses of durable explanatory power which have been tested over a wide variety of conditions are incorporated into theories; 08/08/20115:28 PM 3
TEKS Concepts (C) know that scientific theories are based on natural and physical phenomena and are capable of being tested by multiple independent researchers. Unlike hypotheses, scientific theories are well-established and highly-reliable explanations, but may be subject to change as new areas of science and new technologies are developed; (D) distinguish between scientific hypotheses and scientific theories; (E) design and implement investigative procedures, including making observations, asking well-defined questions, formulating testable hypotheses, identifying variables, selecting appropriate equipment and technology, and evaluating numerical answers for reasonableness; (F) demonstrate the use of course apparatus, equipment, techniques, and procedures, including multimeters (current, voltage, resistance), triple beam balances, batteries, clamps, dynamics demonstration equipment, collision apparatus, data acquisition probes, discharge tubes with power supply (H, He, Ne, Ar), hand-held visual spectroscopes, hot plates, slotted and hooked lab masses, bar magnets, horseshoe magnets, plane mirrors, convex lenses, pendulum support, power supply, ring clamps, ring stands, stopwatches, trajectory apparatus, tuning forks, carbon paper, graph paper, magnetic compasses, polarized film, prisms, protractors, resistors, friction blocks, mini lamps (bulbs) and sockets, electrostatics kits, 90-degree rod clamps, metric rulers, spring scales, knife blade switches, Celsius thermometers, meter sticks, scientific calculators, graphing technology, computers, cathode ray tubes with horseshoe magnets, ballistic carts or equivalent, resonance tubes, spools of nylon thread or string, containers of iron filings, rolls of white craft paper, copper wire, Periodic Table, electromagnetic spectrum charts, slinky springs, wave motion ropes, and laser pointers; (G) use a wide variety of additional course apparatus, equipment, techniques, materials, and procedures as appropriate such as ripple tank with wave generator, wave motion rope, micrometer, caliper, radiation monitor, computer, ballistic pendulum, electroscope, inclined plane, optics bench, optics kit, pulley with table clamp, resonance tube, ring stand screen, four inch ring, stroboscope, graduated cylinders, and ticker timer; (H) make measurements with accuracy and precision and record data using scientific notation and International System (SI) units; (I) identify and quantify causes and effects of uncertainties in measured data; (J) organize and evaluate data and make inferences from data, including the use of tables, charts, and graphs; (K) communicate valid conclusions supported by the data through various methods such as lab reports, labeled drawings, graphic organizers, journals, summaries, oral reports, and technology-based reports; and (L) express and manipulate relationships among physical variables quantitatively, including the use of graphs, charts, and equations. (3) Scientific processes. The student uses critical thinking, scientific reasoning, and problem solving to make informed decisions within and outside the classroom. The student is expected to: (A) in all fields of science, analyze, evaluate, and critique scientific explanations by using empirical evidence, logical reasoning, and experimental and observational testing, including examining all sides of scientific evidence of those scientific explanations, so as to encourage critical thinking by the student; (B) communicate and apply scientific information extracted from various sources such as current events, news reports, published journal articles, and marketing materials; (C) draw inferences based on data related to promotional materials for products and services; (D) explain the impacts of the scientific contributions of a variety of historical and contemporary scientists on scientific thought and society; (E) research and describe the connections between physics and future careers; and (F) express and interpret relationships symbolically in accordance with accepted theories to make predictions and solve problems mathematically, including problems requiring proportional reasoning and graphical vector addition. (6) Science concepts. The student knows that changes occur within a physical system and applies the laws of conservation of energy and momentum. The student is expected to: (6) Science concepts. The student knows that changes occur within a physical system and applies the laws of conservation of energy and momentum. The student is expected to: (E) describe how the macroscopic properties of a thermodynamic 08/08/20115:28 PM 4
Topics Essential Facts (A) investigate and calculate quantities using the work-energy theorem in various situations; Readiness (B) investigate examples of kinetic and potential energy and their transformations; Readiness (C) calculate the mechanical energy of, power generated within, impulse applied to, and momentum of a physical system; Readiness (D) demonstrate and apply the laws of conservation of energy and conservation of momentum in one dimension; Readiness Momentum and its Conservation Impulse and Momentum The conservation of Momentum Energy, work and simple machines Energy and Work Machines 1. Momentum problems always views conditions before and after an event. 2. The momentum of the object is defined by its mass and velocity. 3. An impulse given to an object is the result of an applied force applied over a period of time. 4. The impulse on an object equals the change in momentum of the object. 5. Newton s third law of motion is related to the law of conservation of momentum in collisions and explosions. 6. There are very definite conditions that must be met for momentum to be conserved. 7. The propulsion of rockets and be explained with the conservation law of momentum. 8. Momentum problems in two dimensions can be solved with vector analysis. 1. The relationship between work and energy is not just arithmetic. 2. Work done by a force requires that the force move through a parallel distance to the applied force. 3. All applied force do not result in work. 4. Work is related to power by time. 5. Power can be calculated by knowing the work done and the time frame in which the work was done. 6. Simple machines are useful in our everyday life. 7. The mechanical advantage of an ideal machine is determined by system such as temperature, specific heat, and pressure are related to the molecular level of matter, including kinetic or potential energy of atoms; Supporting (F) contrast and give examples of different processes of thermal energy transfer, including conduction, convection, and radiation; Supporting (G) analyze and explain everyday examples that illustrate the laws of thermodynamics, including the law of conservation of energy and the law of entropy. Supporting 08/08/20115:28 PM 5
Language of Instruction Misconceptions State Assessment Connections National Assessment Connections Resources Student Investigations/Student Products the efficiency of the machine. 8. The mechanical advantage of an ideal machine is 100% 9. A compound machine is composed of a series of simple machines working together for a one outcome. 10 A compound machine can be separated into simple machines. 11. The efficiency for a compound machine is the sum of the efficiencies of the simple machines. angular momentum, closed system, external force, impulse, impulse-momentum theorem, internal force, isolated system, law of conservation of momentum, linear momentum compound machine, efficiency, effort force, energy, ideal mechanical advantage, joule, kinetic energy, machine, mechanical advantage, power, resistance force, watt, work, work-energy theorem 1. Students have difficulty accepting that forces always occur in pairs. 2. Action reaction forces are difficult to understand and momentum is very abstract especially its vector nature. Therefore the distinction between internal and external forces is not obvious to new physics students. 3. In re-coil and explosion events students do not recognize the initial momentum as equal to zero which results in the momentum sum of zero after the event. 1. Students will be challenged again with the idea of balanced and unbalanced forces and the force doing work. 2. While the statement Power is the rate at which work is done is true, it is also too restrictive. Power is the rate for energy transfer which is critical in the study of heat flow, electrical transmission and mass transfer. 3. A simple pulley has a mechanical advantage of 1 as it simply redirects to the force applied to the rope. Pocket Lab Cart momentum on page 205 in text Pocket Lab Skateboard Fun on page 208 in text The Explosion Lab on page 213 in text Pocket Lab Working out on page 225 of the text Pocket Lab An inclined mass on page 227 of the text Your Power Lab on page 232 of the text. Absolute zero, boiling point, calorimeter, conduction, convection, entropy, first law of thermodynamics, heat, heat engine, heat of fusion, heat of vaporization, Kelvin, kinetic-molecular theory, melting point, radiation, second law of thermodynamics, specific heat, temperature, thermal energy, thermal equilibrium, thermodynamics, thermometer 1. Students believe that matter, such as air, are made of identical particles. 2. Students are not aware of the large amount of energy needed for phase changes. 3. Students do not relate gaining and losing heat with the transfer of energy. Often they have the idea that energy is created and destroyed. 4. Students believe that fruit sprayed with water in the winter actually freezes the fruit, rather than 08/08/20115:28 PM 6
Core Labs Textbook Correlation Other Curricular Connection (ELA, Math, S.S., Technology) Pocket Lab wheel and Axle on page 236 of the text PASCO Impulse Momentum Billistics Lab Pendulum Physics: Principles and Problems Chapter 9 Physics: Principles and Problems Chapter 10-11 Dallas County Video Streaming- Power Videos: Search by TEKS http://www.powervideos.org Released TIMMS Questions http://modeling.asu.edu Regents Exam Resources AAPT Physical Science Resource Center www.webassign.net Virtual Physics Simulations-Energy Science TEKS Toolkit Proquest (Physics & Society) Specific Heat Lab Heat of Fusion Physics: Principles and Problems Chapters 12 13 Dallas County Video Streaming- Power Videos: Search by TEKS http://www.powervideos.org Released TIMMS Questions http://modeling.asu.edu Regents Exam Resources AAPT Physical Science Resource Center www.webassign.net Virtual Physics Simulations-Energy Science TEKS Toolkit Proquest (Physics & Society) 08/08/20115:28 PM 7