UNIT COVER PAGE Regular & Honors Physics School District: Bremen Dist. 228 Department: Science Course: Physics Unit Title: Mechanics Grade Levels: 9, 11 & 12 Topic Areas: Work & Energy Time Frame: 3 weeks Date Created: 5/10/2005 Date Modified: Unit Designer(s): John Williams Link to State Standards 11.11.01 13.B.5C 12.11.64 12.11.67 13.11.07 Understand and follow procedures relating to scientific investigations, including understanding the design and procedures used to test a hypothesis, organizing and analyzing data accurately and precisely, producing and interpreting graphs, performing appropriate calculations, applying basic statistical methods to the data, and being able to evaluate conclusions. Design and conduct an environmental impact study, analyze findings and justify recommendations. Understand that energy, defined somewhat circularly, is the ability to change matter, or the ability to do work. Understand that energy is defined by the way it is measured or quantified. Understand the difference between potential and kinetic energy. Know the first two laws of thermodynamics: (1) Energy is conserved (neither created nor destroyed) and (2) Heat flows naturally from a hot object to a cold object; heat will not flow spontaneously from a cold object to a hot object. Understand that another statement of the Second Law is that no device is possible whose sole effect is to transform a given amount of heat completely into work. Analyze examples of resource use, technology use or conservation program and make recommendations for improvements. Link to Department Learner Program Outcomes (LPO) 5.9.1.2 5.9.1.4 5.12.2.1 5.13.1.4 5.10.2.30 TLW use scientific and/or technological instruments such as balances, meter sticks, graduated cylinders and thermometers to make observations and/or measurements. TLW will use scientific instruments to take work and energy measures of physical and chemical systems. TLW apply the scientific method to real life by collecting, analyzing and/or evaluating data in an accurate and objective manner TLW use basic math concepts to solve problems involving data analysis and science calculation TLW understand and apply the concepts of work, energy and conservation. 1
Summary of Unit Students will learn the fundamental principles relating the concepts of energy and power by adding to physics concepts already studied and every day experiences. By expanding upon knowledge of force, distance and time, the student will grow to understand how work and energy are derived from these and add to their physics lexicon by differentiating their physics meaning from their everyday meaning. Resources Text, teacher, supplements, computers, internet, lab equipment, lab manual, videos Key Words Work, energy, power, joules, calories, BTU s, therms, watts, kilowatts, kinetic energy, potential energy, gravitational potential energy, electrical potential energy, elastic potential energy, chemical potential energy, conservation of energy, force, distance, time, rate 2
STAGE 1: IDENTIFY DESIRED RESULTS Enduring Understandings Students will understand that conservation of energy states that energy is never lost; it s merely converted from one form to another power, work and energy are not the same there is a distinction between kinetic and potential energy. Essential Questions Why is there no way to get rid of energy? (perspective) Where does energy go when something stops? (explanation) Why does doubling speed quadruple stopping distance? (application) How is energy converted through a walkman or CD player? (interpretation) How does it feel to increase kinetic energy? (empathy) How much power can you generate? (self-knowledge) Knowledge and Skills Students will know Definitions of work, energy and power The work-energy theorem Students will be able to Analyze situation involving conversion of energy between forms Calculate velocity and potential energy changes based on conservation of mechanical energy Students will be familiar with Principles of simple machines including selecting the best on for a particular job Relative effects of friction of real-world energy problems. Why do you not have to add power to a roller coaster after the first hill and how can you calculate speed? 3
STAGE 2: DETERMINE ACCEPTABLE EVIDENCE What evidence will show that students understand? Required Assessments (brief description) Household and personal energy audit. Includes: all major electrical and gas energy used based on listing of household items of each type and estimated daily usage hours compare consumption to a household bill to find where energy savings could be made. automobile energy usage based on miles/year divided by 365 personal energy consumption (calorie content) all energy types should be converted to Joules and compared Self-Knowledge Regular: Determining power as a firefighter Honors: Determining power as an athlete Other Assessments (brief description) Quizzes Tests Labs Projects Homework 4
Learning Activities PLAN LEARNING EXPERIENCES AND INSTRUCTION What sequence of teaching and learning experiences will equip students to develop and demonstrate the desired understandings? W H E How will you ensure that all students know where they are headed in the unit, why they are headed there, and how they will be evaluated? Publish and discuss unit objectives Use K-W-L charts Use concepts mapping How will you hook students at the beginning of the unit? Demonstration: Show pendulum and discuss how energy changes form continually and ask why it eventually stops. Demonstration: Have a student carry a heavy bowling ball across the room at constant height and another lift a feather from the ground and tell the students the feather lifter did more work. What events will help students experience and explore the big idea and questions in the unit? How will you equip them with needed skills and knowledge? Students can find the energy to jump at various heights and calculate their own personal kinetic energy. R E T How will you cause students to reflect and rethink? How will you guide them in rehearsing, revising, and refining their work? Have students define what they think they physics definition of work is and/or answer pre-unit questions then revisit their original ideas near the end of the unit and write a reflection on how their understanding has changed and what/when made the biggest impact in their thinking. How will you help students to exhibit and self-evaluate their growing skills, knowledge, and understanding throughout the unit? Students can calculate the work to do various everyday activities and their power usage at home by analyzing electrical bills, etc. This will allow a better personal metric for energy and power usage. How will you tailor and otherwise personalize the learning plan to optimize the engagement and effectiveness of ALL students, without compromising the goals of the unit? Students will be presented with several different sources of information including lecture, lab, guided reading assignments and videos. O How will you organize and sequence the learning activities to optimize the engagement and achievement of ALL students? Engagement and achievement will be optimized by using the book at the start of the unit to get student interest and then sequentially building skills. 5
Essential Questions at Topic Level Use the six facets of understanding to generate possible essential questions for the topic of your three-circle audit (curricular priorities). Explanation Interpretation How is energy converted through a walkman or CD player? Where does energy go when something stops? Application Why does doubling speed quadruple the stopping distance? (Topic Area) Work & Energy Empathy How does it feel to increase kinetic energy? Self-Knowledge How much power can you generate? Perspective Why is there no way to get rid of energy? 6
Creating Possible Performances Performance verb Generalization Performance Possible performances for Work/Energy (topic/unit) Facet One: Explanation 1. Explain where energy goes when something stops moving by writing a paragraph using a real-world example. Facet Two: Interpretation 2. List in detail all energy conversions that take place in a CD player by writing an essay. Facet Three: Application 3. Illustrate the relationship between speed and stopping distance by drawing a picture. Facet Four: Perspective 4. Understand how much energy we use today by comparing energy usage to that of 100 years ago. Facet Five: Empathy 5. Demonstrate an increase kinetic energy by pretending to be a slow-moving nitrogen molecule. Facet Six: Self-Knowledge 6. Determine how much energy you produce by determining your horsepower 7
Performance Task Blueprint (Regular) Unit: Mechanics Type: Self-Knowledge Topic Area: Work & Energy Time Frame: 3 class periods Goal Demonstrate the differences between power and work in terms of activities and experiences students can relate to. Role The student is a candidate for firefighter. Firefighters need to be powerful to quickly move equipment up stairs in tall buildings and rescue people. The student will measure his/her power using physics. Audience Fire Chief (teacher) Situation The activity will take place over a three day period of time, taking partial days the first and second and a full day should be allocated on the third day to do the lab itself. Day 1: Students do practice problems using similar skills to the lab. These problems could use similar concepts, shoveling coal to a 1.0 meter height, or a football player having to run up stairs in a timed fashion. Day 2: Students will review previous day s homework or in-class assignment where teacher will assess them. When the students are ready, a review of the next day s lab will take place with careful emphasis on why the lab is being done in terms of physics concepts covered and real life importance of concepts. Day 3: Lab day. Students do lab as described. Product or Performance 1. Worksheet with related problems from Day 1. 2. Pre-lab assignment checked off from Day 2. 3. Lab write-up from lab itself due the day following the lab. Standards Shows work: 80% Units given: 10% Significant figures: 10% 8
Student Performance Task Unit: Mechanics Work & Energy Task: Self-Knowledge Course: Regular Physics Time Frame: 1 period Overarching Understanding: Students will understand that energy influences people s every day life. Enduring Understanding: Students will understand that power, work and energy are not the same. Essential Question: How much power can you generate? Vignette: Fires destroy property and people s lives in minutes. For this reason, firefighters need to do their work in a short amount of time. Remember that power is how quickly work is done. It is not enough for a firefighter to simply do the work; he/she has to do the work quickly, so time matters when you are fighting a fire! You are a candidate for a firefighting position. You need to impress the Fire Chief that you can do the job quickly when it counts. To do this, you need to provide the Chief with the objective data on just how powerful you are, so the Chief can compare you with other candidates for the open position. Standard: (Procedure on back side of task sheet) Complete a technical lab report including all work in the calculations. Rubric: Shows work: 80% Units given: 10% Significant figures: 10% 9
Student Performance Task (regular) Work & Materials: Good shoes Pencil to record results Stopwatch Stairs Meter stick Scale Procedure: 1. Weigh yourself on the scale provided and convert the weight to an equivalent mass in kg. 2. Measure the height of a stair step (riser) and count the number of stair steps. Use this to calculate the height you will be running up. 3. Run up the stairs quickly but safely, with your partner timing you. 4. Repeat this run up to three times and take note of your best time. 5. Use your recent work and power problem solving skills to help find how powerful you are! Run: Time (sec): Height (m): Work (J): Power (W): 1 2 3 Report: Write a formal lab report to the Chief. Include all work in your calculations. The Chief will be impressed by your technical knowledge, since firefighters need that too. Assume whatever power numbers you have are impressive ones and include the reasons why you d be a terrific firefighter. 10
Performance Task Blueprint (honors) Unit: Mechanics Type: Self-Knowledge Topic Area: Work & Power Time Frame: 1 class period Goal Demonstrate the difference between power and work in terms of activities and experiences students can relate to. Role The student is to assume the role of a potential college or professional athlete. As such, he/she needs data to impress athletic scouts, coaches, etc and this activity will provide the data. Audience Division I Coach Situation First, meet in class and give a short explanation and pass out necessary materials. Next, students will gather near stairs by outdoor bleachers or indoor stairs for two-story buildings, transporting necessary materials with them. Materials include 1 kg masses, stopwatches, calculators, pencil and paper. Product or Performance Athletic résumé Standards Shows work: 80% Units given: 10% Significant figures: 10% 11
Student Performance Task Unit: Mechanics Work & Energy Task: Self-Knowledge Course: Honors Physics Time Frame: 1 Period Overarching Understanding: Students will understand that energy influences people s every day life. Enduring Understanding: Students will understand that power, work and energy are not the same. Essential Question: How much power can you generate? Vignette: You are a high school senior, varsity athlete at the top your game, and you have the potential to play for a Division I college or professional league. You need to impress the head coach of your sport by determining the amount of power you can produce. Standard: (Procedure on back side of task sheet) Complete an athletic résumé You will be graded on the following scale: Shows work: 80% Units given: 10% Significant figures: 10% 12
Student Performance Task (honors) Work & Power Background: Power is a measure of how fast work can be done on or by an object. During this activity, you will measure the amount of work required to do two different tasks and will time yourself as you do them. From this information, you can calculate the power you can provide using your arms and legs. Materials: 1 kg mass Stairs Meter stick Stopwatch Procedure: Power of Your Arms 1. Stand while holding a 1 kg mass in your hand. Start with your arm held straight down by your side. 2. Lift the mass up to your shoulder and have your partner measure the distance it travels upward. List this in the table below. 3. Using the stopwatch, determine the time required to lift the 1 kg mass up (and back down) 25 times. Do this as fast as possible without hurting yourself. Be careful not to drop the mass. 4. Using half of the total time, fill in the data table. 5. Determine the amount of work and power your arms have done. Weight: Height: Number of Time: Total Distance: Half Time: Work: Power: Horsepower: Procedure: Your Power (Legs Lifting You) 1. Go to the staircase closest to the classroom. Count the number of steps in the staircase. Record in the table below. 2. Measure the height of one step (riser). Record in table below. 3. Determine your weight. 4. When your partner is ready with the stopwatch, run up the steps as quickly but safely as possible. Record the times in the data table. 5. Determine the amount of work and power your legs have done. 13
Number of Steps: Height of Step: Your Weight: Total Vertical Distance: Time up Steps: Work: Power: Horsepower: Athletic Résumé: In your résumé, you will want to consider the following questions: 1. Why didn t we include the distance your arm moved back down from your shoulder? Weren t you doing work then also? 2. Why did we divide the time you lifted the weight in half? 3. Compare your arm s power to 1 HP. Does this answer surprise you? Explain. 4. Compare your leg s power to 1 HP. Did you have 1 HP? Why or why not? 14