Course: Physics
I. Grade Level/Unit Number: Physics Unit 5
II: Unit Title: Work and Energy
III. Unit Length: 10 days (block schedule) or 18 days (traditional schedule)
IV. Major Learning Outcomes:
This unit is focused on the concepts of work and energy. Students will learn about the relationships between force, displacement, kinetic energy, and potential energy. Specifically students will be able to:
Application of Graphical and Mathematical Tools
Work: Identify work as a transfer of energy Recognize work as the area under a force vs. distance graph Conservation of energy: Describe energy transfer and storage in a variety of physical system Solve problems using conservation of energy Design and conduct experiments exploring conservation of energy Power: Define power as the rate at which work is done Solve problems involving work and power
V. Content Objectives Included (with RBT Tags):
COMPETENCY GOAL 1: The learner will develop abilities necessary to do and understand scientific inquiry. 1.1 Identify questions and problems that This goal and these objectives are an can be answered through scientific integral part of each of the other goals. In investigations. order to measure and investigate scientific phenomena, students must be given the (RBT B2, B3, C2, C3) opportunity to design and conduct their own investigations in a safe laboratory. The students should use questions and models to formulate the relationship identified in their investigations and then report and share those finding with others Students will be able to: Develop questions for investigation from a given topic or problem.
Physics- Unit 5 DRAFT 1 1.02 Design and conduct scientific Distinguish and appropriately graph investigations to answer questions about dependent and independent the physical world. variables. • Create testable hypotheses. • Identify variables. Discuss the best method of • Use a control or comparison group when graphing/presenting particular data. appropriate. • Select and use appropriate measurement Use technology resources such as tools. graphing calculators and computers • Collect and record data. to analyze data. • Organize data into charts and graphs. • Analyze and interpret data. Report and share investigation • Communicate findings. results with others.
(RBT C2, C3, C4, C5, C6) 1.03 Formulate and revise scientific Use questions and models to explanations and models using logic and determine the relationships evidence to: between variables in investigations. • Explain observations. Use evidence from an investigation • Make inferences and predictions. to support a hypothesis. • Explain the relationship between evidence and explanation.
(RBT B2, B6, C2, C6) 1.04 Apply safety procedures in the Predict safety concerns for laboratory and in field studies: particular experiments • Recognize and avoid potential hazards. o Electricity • Safely manipulate materials and o Projectiles equipment needed for scientific Relate physics concepts to safety investigations. applications such as: o Transportation: seat belts, (RBT B3, C3) air bags, speed… Short circuits, circuit breakers, fire hazards
Physics- Unit 5 DRAFT 2 6.01 Investigate Develop the concept of energy as the ability to cause change. and analyze Describe energy transfer and storage in different physical energy storage and transfer systems, including but not limited to those involving mechanisms: gravitational potential energy, elastic potential energy, thermal • Gravitational energy, and kinetic energy. potential energy. Apply proportional reasoning to the relationship between an • Elastic potential energy. object’s kinetic energy and the object’s mass and velocity • Thermal 1 2 according to the equation: KE= mv energy. 2 • Kinetic energy. Analyze changes in gravitational potential energy when an (RBT C3) object’s mass and/or height change: PEg = m gh Apply proportional reasoning to the relationship between a spring’s potential energy and its deformation, x, according to 1 2 the equation: PE= kx s 2
Show that PEs = area under a graph of Force vs. deformation (stretch or compression), where F= - kx . The spring constant k is equal to the slope of the graph and is called the elastic constant. Analyze conceptually that thermal energy increases when an object’s temperature increases. Apply the idea that energy can be transferred when objects interact. (See work under 6.02) Express and apply the idea that in all situations, energy tends to dissipate throughout the environment. Express the concept of energy conservation by applying the idea that energy can be stored and transferred, but cannot be created or destroyed. Express an understanding of the conservation of energy in words as well as charts, diagrams and graphs. 6.02 Analyze, Use conceptual analysis and mathematical formulas for evaluate, and energy to determine amounts of energy stored as kinetic apply the energy, elastic potential energy, gravitational potential energy, principle of and amounts of energy transferred through work. conservation of Analyze and investigate the relationship among kinetic, energy. potential, and other forms of energy to see that total energy is (RBT B2, C4, conserved. (pendulum in various positions, ball in flight, C3) stretching a rubber band, hand generator, turbine) Solve problems relating the amounts of energy stored and transferred applying the principle of conservation of energy.
Physics- Unit 5 DRAFT 3 6.03 Analyze, Identify work as the transfer of energy by a force acting evaluate, and through a distance, when that force acts in the direction of measure the motion of the object: W= F Dx transfer of Recognize that work is equal to the area under a force vs. energy by a distance graph. force. Define power as the rate of transferring energy or the rate of • Work. doing work. • Power. Use the power equation to solve mathematical problems (RBT B2, C3, C6) involving transfer of energy through work: P=W = F Dt v Recognize that a force must cause displacement in order for work to be done. 6.04 Design and Verify through investigations the conservation of energy in conduct situations involving transfer of energy among kinetic energy, investigations of: elastic potential energy and gravitational potential energy. • Mechanical Investigate power. energy. • Power. (RBT C4, C6)
Honors Honors topics: Catapult construction
VI. English Language Development Objectives (ELD) Included: NC English Language Proficiency (ELP) Standard 4 (2008) for Limited English Proficiency Students (LEP)- English Language learners communicate information, ideas, and concepts necessary for academic success in the content area of science.
Suggestions for modified instruction and scaffolding for LEP students and/or students who need additional support are embedded in the unit plan and/or are added at the end of the corresponding section of the lessons. The amount of scaffolding needed will depend on the level of English proficiency of each LEP student. Therefore, novice level students will need more support with the language needed to understand and demonstrate the acquisition of concepts than intermediate or advanced students.
VII. Materials/Equipment Needed: Most of the activities for this unit use inexpensive and simple materials. Those materials can be found here. wooden block with an eye bolt Spring scale attached Meter stick Flat board (to be used as ramp) Books to prop ramp Electronic balance
Physics- Unit 5 DRAFT 4 Masking tape Loose masses
VII. Detailed Content Description:
Please see the detailed content description for each objective in the biology support document. The link to this downloadable document is in the Physics Standard Course of Study at:
http://www.ncpublicschools.org/curriculum/science/scos/2004/27physics
VIII. Unit Notes:
Overview of Unit Four: This unit is focused on the concept of energy. Students will learn about the relationships between force, displacement, work, and energy.
The Unit Guide below contains the activities that are suggested to meet the Standard Course of Study (SCOS) Goals for Unit Four. The guide includes activities, teacher notes on how to implement the activities, and resources relating to the activities which include language objectives for LEP (Limited English Proficient) students. Teachers should also consult the Department of Public Instruction website for English as a Second Language at: http://www.ncpublicschools.org/curriculum/esl/ to find additional resources. If a teacher follows this curriculum (s)he will have addressed the goals and objectives of the SCOS. However, teachers may want to substitute other activities that teach the same concept. Teachers should also provide guided and independent practice from the textbook or other resources.
Physics Support Document Teachers should also refer to the support document for Physics at http://www.ncpublicschools.org/curriculum/science/scos/2004/27physics for the detailed content description for each objective to be sure they are emphasizing the specified concepts for each objective.
Reference Tables The North Carolina Physics Reference Tables were developed to provide essential information that should be used on a regular basis by students, therefore eliminating the need for memorization. It is suggested that a copy be provided to each student on the first day of instruction. A copy of the reference tables can be downloaded at the following URL:
http://www.ncpublicschools.org/docs/curriculum/science/scos/2004/physics/referenceta bles.pdf
Physics- Unit 5 DRAFT 5 Essential Questions for Unit Four Essential questions are those questions that lead to student understanding. Students should be able to answer these questions at the end of an activity. Teachers are advised to put these questions up in a prominent place in the classroom. The questions can be answered in a journal format as a closure. 1. Explain how the direction of motion affects work. 2. What process can be used to calculate the work done on an object by a force at an angle with the displacement? 3. Explain the energy principles used by various methods of generating electricity. 4. Describe the transformations of energy during a bungee jump. 5. Calculate an object’s final velocity based on its initial potential energy. 6. Develop a procedure to find the relationship between work and kinetic energy. 7. Analyze the use of conservation of energy in a catapult or trebuchet.
Modified Activities for LEP Students Those activities marked with a have a modified version or notes designed to assist teachers in supporting students who are English language learners. Teachers should also consult the Department of Public Instruction website for English as a Second Language at: http://www.ncpublicschools.org/curriculum/esl/ to find additional resources.
Computer Based Activities Several of the recommended activities are computer based and require students to visit various internet sites and view animations of various biological processes. These animations require various players and plug-ins which may or may not already be installed on your computers. Additionally some districts have firewalls that block downloading these types of files. Before assigning these activities to students it is essential for the teacher to try them on the computers that the students will use and to consult with the technology or media specialist if there are issues. These animations also have sound. Teachers may wish to provide headphones if possible.
Web Resources The web resources provided on this page were live links when the unit was designed. Please keep in mind that as individuals make changes to websites, it is possible that the websites may become inactive. These resources are provided to supplement the activities in the unit. Some of the resources can be used as to supplement your teacher- led discussions by projecting them for the class. Other activities require students to have access to computers.
WEB RESOURCES FOR WORK AND ENERGY Source Description http://www.article19.com/shockwave/ph.htm “Powerhouse” is a simulation that
Physics- Unit 5 DRAFT 6 allows students to see the energy consumed by different appliances in the home and to calculate the cost of the appliance. http://www.learner.org/interactives/parkphysic Design a roller coaster and observe s/coaster/ energy concepts in action. http://www.glenbrook.k12.il.us/gbssci/phys/Cl A web source that looks at the concept ass/energy/u5l2c.html of Conservation of Energy through bar graphs. http://surendranath.tripod.com/Applets/Dynam Conservation of energy is applied to a ics/Coaster/CoasterApplet.html track with a vertical loop in this animation. http://nces.ed.gov/nceskids/createagraph/defa Great resource for creating different ult.aspx? types of graphs illustrates concept of ID=b2c5a372d2f74500b34a7d3716f16a4b area under a curve as needed for force vs. position graphs. http://www.glenbrook.k12.il.us/gbssci/phys/Cl This is an excellent site for basic ass/energy/U5L1a.html concepts of work and energy. http://hyperphysics.phy- This incredible site provides a video of astr.gsu.edu/hbase/balls.html#c1 “Newton’s Cradle” and the background of conservation of energy for this device. http://id.mind.net/~zona/mstm/physics/mecha This site provides not only background nics/energy/energy.html on energy but word games to reinforce concepts. http://galileo.phys.virginia.edu/Education/outre A very good lesson plan provides ach/8thGradeSOL/EnergyBallFrm.htm connections to a bouncing ball and energy topics. http://www.glenbrook.k12.il.us/gbssci/phys/m A simulation provides the background media/energy/pe.html for the energy conversions in a simple pendulum. http://www.glenbrook.k12.il.us/gbssci/phys/m This reliable source looks at energy media/energy/se.html transformation in downhill skiing. http://www.glenbrook.k12.il.us/gbssci/phys/m This reliable source looks at energy media/energy/ce.html transformation on a roller coaster. http://scientificsonline.com/product.asp? “The Drinking Bird” is a great motivator pn=3053617&bhcd2=1217543856 in looking at other types of energy rather than mechanical energy. http://www.funderstanding.com/k12/coaster/in This site offers students the opportunity dex.html to design a roller coaster using energy concepts http://www.fwee.org/walktour/ A site relates physics to hydro plants applies the concepts of energy. http://schools.matter.org.uk/Content/HookesL This site explores Hooke’s Law and aw/index.html connects the concept of energy to spring motion.
Physics- Unit 5 DRAFT 7 http://www.wku.edu/pads/exercise.php? Students create energy bar graphs for id=ggfmkqffmlgqooyfgqmmlag a given problem with this online source. http://www.wku.edu/pads/exercise.php? Students create energy bar graphs for id=oaylzqyoagrqggkolrqgmyglo a given problem with this online source. http://hyperphysics.phy- Using a concept map, this site exposes astr.gsu.edu/hbase/hframe.html students to many energy applications. http://ocw.mit.edu/OcwWeb/Physics/8- Video lectures illustrate energy 01Physics-IFall1999/VideoLectures/index.htm concepts in varied ways. http://phun.physics.virginia.edu/demos/hopper A “popper” experiment excites students .html to explore energy concepts. http://www.wfu.edu/physics/demolabs/demos/ Wake Forest University offers high avimov/bychptr/bychptr.htm quality videos illustrating energy concepts through demos. http://apwww.smu.ca/demos/ As another excellent source of videos for energy demos this site is excellent. http://paer.rutgers.edu/PT3/ This is a site for physics teaching resources on energy from Rutgers University. http://jersey.uoregon.edu/vlab/PotentialEnergy This site provides a lesson on kinetic /index.html and potential energy. http://ed.fnal.gov/projects/labyrinth/games/war High energy resource relates to atomic pspeed/race_for_energy/activity.html particle research. http://www.re-energy.ca/t-i_windbuild-1.shtml A site relates physics to generation of energy using wind and applies the concepts of energy. http://www.re- A site relates physics to generation of energy.ca/t_renewablebasics.shtml energy using solar sources and applies the concepts of energy. http://www.re-energy.ca/t_waterpower.shtml A site relates physics to generation of energy using hydro sources and applies the concepts of energy. http://www.compadre.org/Repository/docume Unrestricted lab document connects nt/ServeFile.cfm?ID=3812&DocID=120 the simple pendulum to energy concepts. http://www.myphysicslab.com/spring1.html Using this simulation, students can see the transfer of energy in a vibrating spring. http://www.re-energy.ca/t-i_solarheatbuild- The instructions for building a solar 1.shtml#test_it oven are included as a possible energy project. http://www.fifeschools.com/cjh/staff/laker/toyot A teacher site uses “Hot Wheels a2006.htm Physics” as a grant opportunity. http://monet.physik.unibas.ch/~elmer/pendulu This site presents advanced m/index.html exploration for the simple pendulum and energy concepts.
Physics- Unit 5 DRAFT 8 http://www.wfu.edu/academics/physics/video/l Wake Forest University offers high ecture.html quality videos illustrating energy concepts through lectures. http://www.glenbrook.k12.il.us/gbssci/phys/m Using this link explores conservatives media/energy/au.html forces through energy concepts http://www.ngsir.netfirms.com/englishhtm/Wor Explore energy concepts on an incline k.htm plane.
X. Global Content: Aligned with 21 st Skills: One of the goals of the unit plans is to provide strategies that will enable educators to develop the 21st Century skills for their students. As much as students need to master the NCSOS goals and objectives, they need to master the skills that develop problem solving strategies, as well as the creativity and innovative thinking skills that have become critical in today’s increasingly interconnected workforce and society. The Partnership for 21st Century Skills website is provided below for more information about the skills and resources related to the 21st Century classroom.
http://www.21stcenturyskills.org/index.php? option=com_content&task=view&id=27&Itemid=120 GLOBAL CONTENT—Goal Six
NC SCS 21st Century Skills Activity Physics Communication Skills 1.01, 6.01, Conveying thought or opinions Analysis questions in all labs effectively 6.01, 6.02 When presenting information, Data analysis in all labs distinguishing between relevant and irrelevant information 6.01,6.02, Explaining a concept to others Analysis questions in all labs/ Team 6.03,6.04 Quiz 6.01,6.02, Interviewing others or being Team Quiz 6.03,6.04 interviewed Computer Knowledge 6.01,6.02, Using word-processing and database Energy Poster, Work/KE Lab 6.03,6.04 programs Report 6.01,6.02, Developing visual aids for Energy Poster 6.03,6.04 presentations 6.01,6.02, Using a computer for communication Energy Poster, Work/KE Lab 6.03,6.04 Report 6.01,6.02, Learning new software programs Lab simulation from PhET ( Energy 6.03,6.04 Skate Park) Employability Skills 6.01,6.02, Assuming responsibility for own All lab activities
Physics- Unit 5 DRAFT 9 6.03,6.04 learning 6.01,6.02, Persisting until job is completed All lab activities and team Quiz 6.03,6.04 6.01,6.02, Working independently Energy Poster 6.03,6.04 6.01,6.02, Developing career interest/goals Energy Poster 6.03,6.04 6.01,6.02, Responding to criticism or questions Team Quiz 6.03,6.04 Information-retrieval Skills 6.01,6.02, Searching for information via the Energy Poster, PhET Simulation, 6.03,6.04 computer Catapult Project 6.01,6.02, Searching for print information Energy Poster 6.03,6.04 6.01,6.02, Searching for information using Energy Poster, Team Quiz 6.03,6.04 community, members Language Skills- Reading 6.01,6.02, Following written directions All labs in the unit 6.03,6.04 6.01,6.02, Identifying cause and effect All labs in the unit 6.03,6.04 relationships 6.01,6.02, Summarizing main points after reading Energy Poster 6.03,6.04 6.01,6.02, Locating and choosing appropriate All lab activities 6.03,6.04 reference materials Energy Poster 6.01,6.02, Reading for personal learning Energy Poster 6.03,6.04
Language Skills- Writing 6.01,6.02, Organizing and relating ideas when “Explain” and “Evaluate” sections in 6.03,6.04 writing all lab activities, Lab Report 6.01,6.02, Proofing and Editing Energy Poster, Lab Report 6.03,6.04 6.01,6.02, Synthesizing information from several Energy Poster, Lab Report 6.03,6.04 sources 6.01,6.02, Documenting sources Energy Poster 6.03,6.04 6.01,6.02, Developing an outline Energy Poster 6.03,6.04 6.01,6.02, Writing an outline Energy Poster 6.03,6.04 6.01,6.02, Writing to persuade or justify a position All lab activities 6.03,6.04 6.01,6.02, Creating memos, letters, other forms of Energy Poster 6.03,6.04 correspondence
Physics- Unit 5 DRAFT 10 Teamwork 6.01,6.02, Taking initiative All lab activities and “Team Quiz” 6.03,6.04 6.01,6.02, Working on a team All lab activities and “Team Quiz” 6.03,6.04 Thinking/Problem-Solving Skills 6.01,6.02, Identifying key problems or questions All lab activities and “Team Quiz” 6.03,6.04 6.01,6.02, Evaluating results All lab activities and “Team Quiz” 6.03,6.04
Physics- Unit 5 DRAFT 11 Teacher notes for Intro to Work Lab
Language (ELP) Objective for LEP Students:
ENGAGE: Have a student put on a backpack full of books and walk around the classroom. Ask the class how much work this person is doing. Student answers will vary. Have them draw a free body diagram of the backpack, showing all forces acting on it. Ask for a student volunteer to come put their diagram on the board, and have the class discuss the diagram. The correct diagram should only have two forces; the downward force from gravity, and the upward force exerted by the student’s shoulders. Lead students through a discussion of the fact that since there is no horizontal force, the student is doing no work. Likewise, since the bag is not moving vertically, gravity is also not doing any work. EXPLORE: Students will explore the ideas of work, force, and displacement during the lab activity. EXPLAIN: The analysis questions give students an opportunity to explain the connections between direction of force, displacement, and work. The collaborative nature of lab work also allows students to discuss concepts and explain processes to one another. ELABORATE: The extension to this lab provides an opportunity for students to build on their knowledge by designing their own procedure to determine the work done by a force applied at an angle to the displacement. EVALUATE: Upon completion of this activity, students should be encouraged to write about the concepts they explored. A quickwrite or Think/Pair/Share activity is an excellent way to allow students to judge their own understanding of the concepts.
Physics- Unit 5 DRAFT 12 Lab: Intro to Work Purpose: to determine the amount of work done to an object in various scenarios Materials: wooden block with an eye bolt flat board to be used as a ramp attached books to prop ramp spring scale electronic balance loose masses masking tape meter stick Procedure: 1. Weigh the block using the electronic balance. Record the mass in kilograms.
Part A 2. On a smooth, horizontal surface, mark a starting line and a stopping point with masking tape.
3. Attach the spring scale to the eye bolt, place the block at the starting line, and drag it horizontally at constant velocity with the spring scale. Be sure to keep the force on the scale as constant as possible. Record the force and the distance traveled.
Part B 4. Using the spring scale, lift the block 1.5 meters off of the ground at a constant velocity. Be sure to keep the force on the scale as constant as possible. Record the force and the distance traveled.
Part C 5. Using the books, set up a ramp on the floor. Record the lengths of each leg and the hypotenuse of the ramp.
6. Place the block at the bottom of the ramp. Holding the spring scale parallel to the surface of the ramp, drag the block to the top of the ramp at constant velocity. Record the force used.
7. Draw a free body diagram showing all forces acting on the block as it is pulled up the ramp.
Data Mass of the block : ______kg
Part A Part B Direction of force
Physics- Unit 5 DRAFT 13 Distance Traveled (m)
Magnitude of force (N)
Part C Hypotenuse Height (m) Length (m) Force (N) (m)
Free body diagram:
Analysis 1. Calculate the work done by gravity in Part A. Explain your answer. (Hint: think about the relationship between work, direction of force, and displacement)
2. Calculate the work done by the applied force in Part A. Explain your answer.
3. Calculate the work done by gravity in Part B. Should the work be positive or negative? Explain.
4. Calculate the work done by the applied force in Part B. Should it be positive or negative? Explain.
Physics- Unit 5 DRAFT 14 5. In Part C, which distance should be used to calculate the work done by gravity? Should the same distance be used to calculate the amount of work done by the applied force? Explain your answers.
6. Calculate the work done by gravity, and the work done by the applied force. Be sure to use the appropriate signs.
7. Explain how you could calculate the work done by friction in each part of this lab. Would this process be different if the object was accelerating? Explain.
Extension Design a procedure to determine the amount of work done to an object by a force that is at an angle with the horizontal (examples: a sled being pulled across the ground or a lawnmower being pushed).
Physics- Unit 5 DRAFT 15 TEAM QUIZ—WORK AND ENERGY
Language (ELP) Objective for LEP Students:
INTRODUCTION : Using the Team Quiz idea allows students to work together to understand application of equations to problem solving. The teacher creates teams of 2 to 4 students. Included are Team Quiz cards for classes from size 2 to 33. The teacher selects the cards to fit the class enrollment. In addition, if a student is absent then the flexibility is there. Every student gets a copy of the problem but each fills in blanks 1 and 2 with unique numbers. In this way, students are encouraged to work together without the risk of copying. ENGAGE: Remind students that working together is an important part of learning physics EXPLORE: Students must explore a method to solve the various parts of the problem. EXPLAIN: Working together, students explain to each other methods of problem solving. ELABORATE: The problem structure has parts that force students to elaborate on relationships with work and energy. EVALUATE: Students evaluate the correctness of their method using the team total.
PROCEDURE: 1. Cut up card sheet. If desired, staple each Quiz to a note card to make them more durable for use year after year. 2. Give each student a copy of the problem. 3. Explain how to fill in blanks. Each student selects a row and works each part of the problem with the given data. 4. Explain the difference between individual totals and team totals. Individual totals are the sum of the answers to all parts “a”-“e” and Team Total is the sum of all individual totals. 5. Emphasize that all work must be shown for credit and that work as well as answers will be checked. The spreadsheet is included so that individual answers may be checked.
Physics- Unit 5 DRAFT 16 Team Quiz—Work and Energy Name: A 200 kg load is lifted vertically a distance of ______meters with an acceleration of ______meters/second2 upward by a rope attached to the load. Determine: a) The tension in the rope: ______
b) The work done by the rope on the load:______
c) The work done by gravity on the load: ______
d) The net work done on the load by all the forces acting: ______
e) The final speed of the load (assuming that the load started at rest): ______
Your Individual Total: ______
TEAM QUIZ WORK TEAM QUIZ WORK Tea Pers distanc acceleratio Tea Perso distanc acceleratio m on e-m n m/s^2 m n e-m n m/s^2 1 1 2 4 2 1 1.2 1.6 1 2 3 3 2 2 2.2 1.8 1 3 5 2 2 3 3.2 2.2 1 4 4 5 2 4 4.2 2.4 Tea Total Team Total = 18653 m = 29459
TEAM QUIZ WORK TEAM QUIZ WORK Tea Pers distanc acceleratio Tea Perso distanc acceleratio m on e-m n m/s^2 m n e-m n m/s^2 3 1 1.4 2.1 4 1 1.6 5.3 3 2 2.4 2.3 4 2 2.6 5.1 3 3 3.4 2.5 4 3 3.6 4.9 3 4 4.4 2.7 4 4 4.6 4.7 Tea Team Total = 36262 m Total= 21311
Physics- Unit 5 DRAFT 17 TEAM QUIZ WORK TEAM QUIZ WORK Tea Pers distanc acceleratio Tea Pers distanc acceleratio m on e-m n m/s^2 m on e-m n m/s^2 5 1 7 3 6 1 5 4 5 2 5 3.2 6 2 4 4.2 5 3 3 3.4 6 3 3 4.4 5 4 2 3.6 6 4 2 4.6 Tea Tea m Total= 32260 m Total= 34982
TEAM QUIZ WORK TEAM QUIZ WORK Tea Pers distanc acceleratio Tea Pers distanc acceleratio m on e-m n m/s^2 m on e-m n m/s^2 7 1 7 1.8 8 1 6 3 7 2 6 2 8 2 4 4 7 3 5 2.3 8 3 3 5 Team Total = Team Total = 27897 21555
TEAM QUIZ WORK TEAM QUIZ WORK Tea Pers distanc accelerati Pers distanc acceleration m on e-m on m/s^2 Team on e-m m/s^2 9 1 3.2 4 10 1 6 1.1 9 2 3.7 3 10 2 8 1.5 9 3 3.9 2 Team Total = 11888.53 Team Total = 20373.72
TEAM QUIZ WORK TEAM QUIZ WORK Tea Pers distanc accelerati m on e-m on m/s^2 11 1 7 4.2 11 2 5 4.8 Team Total = 27094.60
Physics- Unit 5 DRAFT 18 ANSWERS: TEAM 1 Tension- Work of Work of Final speed- Individual N rope -J gravity-J Net work-J m/s total 2760 5520 -3920 1600 4.00 5964.00 2560 7680 -5880 1800 4.24 6164.24 2360 11800 -9800 2000 4.47 6364.47 2960 11840 -7840 4000 6.32 10966.32 Team Total 29459.04
TEAM 2 Tension- Work of Work of Final speed- N rope -J gravity-J Net work-J m/s 2280 2736 -2352 384 1.96 3049.96 2320 5104 -4312 792 2.81 3906.81 2400 7680 -6272 1408 3.75 5219.75 2440 10248 -8232 2016 4.49 6476.49 Team Total 18653.02
Team 3 Tension- Work of Work of Final speed- N rope -J gravity-J Net work-J m/s 2380 3332 -2744 588 2.42 3558.42 2420 5808 -4704 1104 3.32 4631.32 2460 8364 -6664 1700 4.12 5864.12 2500 11000 -8624 2376 4.87 7256.87 Team Total 21310.75
TEAM 4 Tension- Work of Work of Final speed- N rope -J gravity-J Net work-J m/s 3020 4832 -3136 1696 4.12 6416.12 2980 7748 -5096 2652 5.15 8289.15 2940 10584 -7056 3528 5.94 10001.94 2900 13340 -9016 4324 6.58 11554.58 Team Total 36261.78
TEAM 5 Tension- Work of Work of Final speed- N rope -J gravity-J Net work-J m/s
Physics- Unit 5 DRAFT 19 2560 17920 -13720 4200 6.48 10966.48 2600 13000 -9800 3200 5.66 9005.66 2640 7920 -5880 2040 4.52 6724.52 2680 5360 -3920 1440 3.79 5563.79 Team Total 32260.45
TEAM 6 Tension- Work of Work of Final speed- N rope -J gravity-J Net work-J m/s 2760 13800 -9800 4000 6.32 10766.32 2800 11200 -7840 3360 5.80 9525.80 2840 8520 -5880 2640 5.14 8125.14 2880 5760 -3920 1840 4.29 6564.29 Team Total 34981.55
TEAM 7 Tension- Work of Work of Final speed- N rope -J gravity-J Net work-J m/s 2320 16240 -13720 2520 5.02 7365.02 2360 14160 -11760 2400 4.90 7164.90 2420 12100 -9800 2300 4.80 7024.80 Team Total 21554.71
TEAM 8 Tension- Work of Work of Final speed- N rope -J gravity-J Net work-J m/s 2560 15360 -11760 3600 6.00 9766.00 2760 11040 -7840 3200 5.66 9165.66 2960 8880 -5880 3000 5.48 8965.48 Team Total 27897.13
TEAM 9 Tension- Work of Work of Final speed- N rope -J gravity-J Net work-J m/s 2760 8832 -6272 2560 5.06 7885.06 2560 9472 -7252 2220 4.71 7004.71 2360 9204 -7644 1560 3.95 5483.95 Team Total 20373.72
Physics- Unit 5 DRAFT 20 Team 10 Tension- Work of Work of Final speed- N rope -J gravity-J Net work-J m/s 2180 13080 -11760 1320 3.63 4823.63 2260 18080 -15680 2400 4.90 7064.90 Team Total 11888.53
Team 11 Tension- Work of Work of Final speed- N rope -J gravity-J Net work-J m/s 2800 19600 -13720 5880 7.67 14567.67 2920 14600 -9800 4800 6.93 12526.93 Team Total 27094.60
Physics- Unit 5 DRAFT 21 ENERGY POSTER PROJECT Language (ELP) Objective for LEP Students:
Description: Students will create an energy poster on one of the following topics 1) energy from wind turbines 2) energy generated by hydro plants 3) geothermal energy 4) solar energy 5) energy generated by fission reactors 6) energy generated by fusion reactions 7) solar energy and 8) energy generated by tidal power. Physics energy principles must be featured on the poster as illustrated by the attached rubric. ENGAGE: Use the ongoing discussion about off-shore drilling that North Carolinians may have to eventually vote on to broach the issue of energy sources. Ask students to vote on whether they are in favor of off shore drilling. EXPLORE: After the vote, ask students to list ways of generating energy. Add to the list so that all of the eight possibilities above are listed. EXPLAIN: The poster project provides the student with the opportunity to explain the connections of physics energy concepts to the energy production methods mentioned above in the introduction. ELABORATE: Students have the opportunity to elaborate on application of physics principles to creating energy for consumption. EVALUATE: The rubric allows both students and teacher to evaluate the project.
Possible Web Sites: http://home.nc.rr.com/enloephysics/geo/Geothermal.html http://home.nc.rr.com/enloephysics/hydro/page1.html http://home.nc.rr.com/enloephysics/solar/index.html http://home.nc.rr.com/enloephysics/wind.htm http://www.gcse.com/energy/energy_sources.htm http://fusedweb.llnl.gov/CPEP/ http://www.youtube.com/watch? v=Z_DDj2Q89ic http://www.bbc.co.uk/schools/ks3bitesize/science/physics/energy_transfer_intro.s html http://www.emints.org/ethemes/resources/S00002115.shtml http://www.think-energy.com/ThinkEnergy/Default.aspx
Physics- Unit 5 DRAFT 22 ENERGY PRODUCTION and PHYSICS CONCEPTS
NAME: ______
CATAGORY 4 3 2 1 Physics Content At least four Three major Two major One major major physics physics physics physics work/energy work/energy work/energy work/energy concepts are concepts are concept is concepts are applied applied applied applied Energy The method The method The method The method Production of energy of energy of energy of energy Content production is production is production is production is clearly clearly explained or explained or explained explained or illustrated illustrated but and illustrated somewhat not clearly illustrated clearly. GRAPHICS OR Pictures are Pictures are Pictures are Pictures are ILLUSTRATIONS well chosen well chosen well chosen well chosen for relevance for relevance for relevance for relevance and all are and most are and some but none are documented documented are documented as to source. as to source documented as to source as to source NEATNESS, The poster is The poster is The poster is The poster is ORGANIZATION, very well well organized, somewhat AND GRAMMAR organized, organized, attractive and organized, very attractive and has no more attractive and attractive and has no more than 3 has more has no than 2 spelling or than 3 spelling or spelling or grammar spelling or grammar grammar mistakes. grammar mistakes. mistakes. mistakes.
Physics- Unit 5 DRAFT 23 ENERGY SKATE PARK LAB SIMULATION Language (ELP) Objective for LEP Students:
This activity is an online simulation that may also be downloaded and place on computers that are not online. http://phet.colorado.edu/simulations/sims.php? sim=Energy_Skate_Park
ENGAGE: Introduce the simulation using an LCD projector if possible. The simulation itself is very visually engaging. Show how to build the ramp and mark the path. Practice this yourself so that you may help students if questions arise.
EXPLORE: Students explore the concept of energy conservation and mechanical energy conversion in an open ended method by building a skate park ramp.
EXPLAIN: The questions in the activity focus on explanations for decisions that are made in the simulation.
ELABORATE: Students consider the affect of moving the park to another planet in our solar system.
EVALUATE: Data is collected and potential energy and kinetic energy is calculated as well as total energy. ANSWERS TO QUESTIONS:
1. Student answer
2. Potential energy decreases.
3. Height is distance above a chosen reference line.
4. Student answer.
5. As potential energy decreases along the path, speed increases and therefore kinetic energy increases.
6. Since the mass changes then both potential energy (mgh) and kinetic energy (1/2 mv2) changes.
7. Total mechanical energy is constant.
8. Total mechanical energy decreases.
9. Student answer
Physics- Unit 5 DRAFT 24 10. a) height above reference line b) student answer c) student answer
11. a) student answer b) the force of gravity
Physics- Unit 5 DRAFT 25 SKATE PARK ENERGY LAB NAME:
Use the following URL. http://phet.colorado.edu/simulations/sims.php?sim=Energy_Skate_Park
Your first challenge is to build a good skate park ramp that is safe and will not hurt the skater! Cut off friction (uncheck Thermal Energy) to start with as you create your ramp. Check “Show Grid” so you may draw your final design on the grid below.
Please Note: You may take measurements by using the “Show Path” button. Purple dots will appear to show the path. Click on a purple dot to see the numbers associated with the point. Clear the path when you must take new measurements.
1. What is your starting height? ______m.
2. Potential energy is related to your starting height but the reference point is a decision that must be made in every situation that involves energy. Click “Show Path” and also click “Potential Energy Reference”. What happens to your potential energy when you move the “Potential Energy Reference” line upward? Check several points to see. Measuring Tape
Potential Energy Reference
Show Show path Grid clear
3. What exactly does the word “height” mean in relationship to the skater?
Height = 12.00 m 4. What is your starting speed? ______m/s Speed = 1.83 m/s 5. Kinetic energy is related to the speed of the skater. How does a decrease in potential energy at different points along the path affect kinetic energy? (Assume an unchanging starting point.)
Physics- Unit 5 DRAFT 26 6. Change the skater type. How does this affect potential energy? Kinetic energy? Why?
7. Both potential energy and kinetic energy are classified as “Mechanical Energy”. Pick several points on your path and total the potential energy and kinetic energy. What do you observe?
8. Click the box beside friction. Let’s see what happens to the total mechanical energy (the sum of potential and kinetic energy) when friction is part of the system. What did you observe?
9. Consider the following situation: Put a Skater on your track, select Show Path and display the purple dot data for your starting point. Record that data below. You may use the measuring tape to measure distances. Energy Reference Line Height from PE (J) KE (J) Speed Position (m) Reference Line(m) (m/s)
10.How could you predict the values for another place on the track? a. Describe what you would have to measure.
b. Show your calculations for each value of the point you chose: PE, TE, KE, speed.
PE:
Physics- Unit 5 DRAFT 27 TE:
KE:
SPEED:
c. Use the simulation to check the values you calculated. Record your calculated results and the results from the simulation below.
Calculated PE = TE = KE = Speed =
Simulation PE = TE = KE = Speed =
Physics- Unit 5 DRAFT 28 11. a. Describe what you think will change in your calculations if you move the Skater to Jupiter.
b. What would be the biggest change on Jupiter that affects the skater’s energy?
TEACHER KEY AND RESOURCES for HOT WHEELS PHYSICS Language (ELP) Objective for LEP Students:
This lab activity focuses on conservation of energy, central forces in a loop, and efficiency of a system.
Physics- Unit 5 DRAFT 29 Engage: Take a “Hot Wheels®” car and roll it along the floor or a lab table. Then ask the question “I wonder how much physics we can learn by studying Hot Wheels® Tracks and Cars? Anyone have any suggestions about the physics involved in the Hot Wheels® Tracks and Cars System? If we can come up with three physics applications then we will do a lab with Hot Wheels® Physics.” List all physics applications (types of forces, friction, and types of energy on the board).
Explore: Students investigate the efficiency of the track and make predictions about the release height needed to make the circular loop on the track.
Explain: Students explain their choices in the investigation and the results that follow.
Elaborate: Students must improve the efficiency of the system. They may replace the car, lubricate the tracks, or make the tracks more anchored to the table and less flexible.
Evaluate: The question of efficiency is very energy based and very much a “real life application” of physics. It is a point that must be made as energy becomes a more expensive and sought after resource. Students will realize how inefficient most energy transfer systems are when they calculate the efficiency of the Hot Wheels® Tracks/ Car System.
Teacher Key to Hot Wheels ® Physics: This is intended to be a very open ended activity. Remind students that conservation of energy is different than conservation of mechanical energy (kinetic energy and gravitational potential energy). Energy is conserved in this toy but mechanical energy is not conserved. The percent efficiency is the output mechanical energy divided by the input mechanical energy and the quotient is multiplied by 100. The starting point of the car gives us input energy using mgh1. Measure the height from the low point of the track. The output energy is measured at the top of the loop and has both kinetic energy and gravitational potential energy mgh2 (measured from the bottom of the track).
The math for calculating the release height so that the car just makes the loop follows.
2 mgh1 + 0 = mgh2 + ½ mv (conservation of energy)
Physics- Unit 5 DRAFT 30 -mg – N = -mv2/R (net force equation for car at the top of the loop of radius R) Since the car is going just fast enough to make the loop then N (normal force) =0.
So –mg = -mv2/R.
That means that mv2 =mgR
Putting that back into the energy statement and using h2 = 2R: mgh1= 2mgR + ½ mgR
so theoretically h1 = 2.5 R. In reality h1> 2.5 R
Students will need hints on how to do this.
Sources of “Mattel Hot Wheels G Force” Track Sets (from $12.99- $29.99)
http://astore.amazon.com/hotwheels-20/103-7861526-5919805? %5Fencoding=UTF8&node=7
http://www.boscovs.com/StoreFrontWeb/Product.bos? assortmentDepartmentNumber=6171320&assortmentId=4&itemNumber=23 769&type=Product
http://www.sortprice.com/search-BCQ-20-Toy_Cars_and_Vehicles- Hot_Wheels
Physics- Unit 5 DRAFT 31 HOT WHEELS PHYSICS NAME
PURPOSE: TO INVESTIGATE ENERGY CHANGES ON A HOT WHEELS® TRACK
Your Challenge: Find the theoretical height from where the Hot Wheels car must be released to barely get to the top of the loop. Attach your calculations to this lab. Find the actual height from where the Hot Wheels car must be released to just barely get to the top of the loop. Measure the total mechanical energy in the system at the release point and at the top of the loop. Calculate the percent efficiency of the system comparing the release point and the top of the loop. Improve the percent efficiency of the system and describe how you did so.
Hypothesis: What is your prediction for the release height and the percent efficiency?
State why you predicted this value!
Materials: What do you need? Stopwatches, photogates, motion detectors, etc?
Procedure: What is your plan?
Physics- Unit 5 DRAFT 32 Release Height Data Fill in the chart with appropriate labels using only what is necessary TRIAL 1 2 3 4 5 6
Percent Efficiency Data Fill in the chart with appropriate labels using only what is necessary
TRIAL 1 2 3 4 5 6
DATA: Other (your choice—this chart may not be needed) TRIAL 1 2 3 4 5 6
Physics- Unit 5 DRAFT 33 ANALYSIS: Create two energy questions about this lab and answer them. 1.
2.
CONCLUSION: What did you learn about the efficiency of your track/car set? Where is the missing energy? How did you improve your results and by how much did you improve your efficiency?
Physics- Unit 5 DRAFT 34 Energy and Work Lab Activity-- Teacher Guide Language (ELP) Objective for LEP Students:
Note: This activity works with a motion detector and the following devices: a
Engage: The teacher walks at constant velocity carrying a suitcase or another heavy mass with a handle. Ask students to vote (“physics by democracy”) on one of three answers regarding the work that is done. The voting is best done on small pieces of paper which they turn in before you discuss the answer. POSSIBLE ANSWERS: (1) a lot of work because the object is heavy (2) a small amount of work because the object is not moving very fast (3) zero work because the force is perpendicular to the direction of the displacement. THE ANSWER IS NUMBER (3). Explore: Students explore the relationship between kinetic energy and work in the lab activity. Explain: Students answer questions to explain how and what they investigated in the lab activity. Elaborate: Students elaborate the findings of their lab activity in the “extension” part of their lab. Evaluate: Students are asked to assess whether the “work energy theorem” applies to their own data. LabPro, CBL, Pasco Interface, or a direct connect method such as to TI Inspire CAS. Answers to Questions: Calculations: 1) Student answer—as the teacher, visit each lab team several times to make sure data collection follows correct procedure. Remind students that vo is zero and vf is read directly from the velocity, time graph at the time a change in position equals 0.300 m. 2) The slope of position, time equals velocity and the slope of velocity, time equals acceleration. Use the data collection software to obtain those slopes. The slope of the velocity, time graph is the best method of finding acceleration using a motion detector. Some students will attempt to use the acceleration, time graph but they will find more variation in that graph. 3) Check to see that students convert 30.0 cm to 0.300 m. If students have not seen the unit of energy and work, introduce the “Joule as a kg-m2/s2”.
Analysis: Normal force 1) Student answer may be “yes” or “no”. Some possible reasonsTensio for a “no” answer is the data collection with the motion detector. Make sure that students do not place the cart too close to Tensiothe motion detector. Thatn distancecart varies n Weight of cart Physics- Unit 5 DRAFT 35Weight of hanging mass depending upon the model used so check the specifications that come with the device. 2) The acceleration is the same for both. 3) See the diagram.
4) For the hanging mass: T – 0.050(9.8) = -0.050 a or 0.050(9.8) –T = 0.050 a For the cart where mass = M: -T = -Ma or T = Ma Friction is ignored for the rolling objects. 5) Replace T with Ma in the first equation: Ma - 0.49 = -0.050 a. Group the “a” terms: Ma + 0.050a = 0.49 and factor. So a (M + 0.050) = 0.49. Solve for a: a = [0.49]/ (M + 0.050) where M is the mass of the cart. 6) Student answer may include some mention of friction particularly in the pulley. We are also assuming a “no mass” pulley which ignores the energy required to rotate the pulley (and the wheels of the cart). Extension: The kinetic energy increases and the tension increases. Both indicate that more work is done on the cart.
Physics- Unit 5 DRAFT 36
ENERGY and WORK LAB ACTIVITY Name: Background: Kinetic energy is the “energy of motion”. It takes work to create a change in kinetic energy. Using a motion detector and your knowledge of Newton’s Second Law, you are going to investigate the relationship between work and kinetic energy for a cart. Materials: A motion detector with an interface to a data collection system, a dynamics cart, a pulley with clamp, a 50 gram mass, a meter stick and about 1.5 meters of string. How to Start: Place the dynamics cart on the table with the pulley clamped to the edge of the table. The motion detector is placed at the other edge of the table. Your teacher will give you instruction on the use of the motion detector. Connect one end of the string to the dynamics cart and tie the other end to the mass. Make sure the string is the correct length to allow the mass to fall 50.0 cm and the cart will also move 50.0 cm on the table. This diagram shows how to connect the mass to the dynamics cart over the pulley.
cart Motion detector
50.0c m Collecting Data: Hold the cart at rest on the table with the mass hanging as shown in the diagram. Start data collection with the motion detector. Once you hear the clicking noise from the motion detector, release the cart. Repeat for a total of 5 trials. Use the position, time graph to find the final velocity after the cart travels 50.0 cm from the initial position. Record your data below. (Your teacher will instruct you in obtaining the velocity graph and the slope of your velocity graph after the cart travels 50.0 cm.) Trial Initial velocity Final velocity Slope of velocity, time- (m/s)/s (m/s) (m/s) 1 0 2 0 3 0 4 0 5 0
Record the mass of your dynamics cart here: ______(kg) Calculations:
Physics- Unit 5 DRAFT 37 2 2 1) Calculate the change in Kinetic Energy (½ mvf - ½ mvo ) for all 5 trials. Record results in the table at the bottom of the page. Work area:
2) Using the slope of the velocity, time graph and the cart’s mass, calculate the force acting on the cart by the tension of the string. Record results in the table. Work area:
3) Since Work = Force x Distance (along the line of force), find the work done for the 30.0 cm the cart traveled. Record results in the table. Work area:
TRIAL Change in KE Force Acting Work Done Absolute Difference (J) on Cart (N) by Force (J) Between KE & Work (J) 1 2 3 4 5
Analysis: 1. The “Work-Energy Theorem” is an extremely important law in physics. It states that “the total work done on an object equals the change in kinetic energy of the object”. Does your data support this law? If not, where do you feel an error occurred?
2. Compare the acceleration of the cart and the hanging mass.
3. Draw the free body diagrams for the forces acting on the cart and the hanging mass. Assume very low friction. cart
Physics- Unit 5 DRAFT 38 4. Write the force equations for the forces acting on each of the masses.
5. Solve the equations for the acceleration of the cart. Show work below. Record your answer: calculated value of a= ______m/s2
6. How does your calculated value of the acceleration compare with the experimental value of acceleration? Elaborate on how you could improve your results!
Extension: How would the work done change over the 50.0 cm distance if the hanging mass increases? Explain:
Teacher notes for Work/Kinetic Energy Lab
Physics- Unit 5 DRAFT 39 Language (ELP) Objective for LEP Students:
ENGAGE: This activity should be done after students have a good understanding of work, kinetic energy, and potential energy. Tell students that they will be designing their own experiment to determine the relationship between the work done to an object and that object’s change in kinetic energy. The teacher should provide a large variety of materials for use such as: meter sticks, stopwatches, ramps, tennis, golf, or other small balls, and Labpros with motion detectors (if available). Encourage students to ask for any other equipment that they might need.
EXPLORE: Students will use a variety of lab equipment to explore the relationship between work and kinetic energy. As students are working on their experiments, the teacher should circulate between groups asking probing questions to help guide students.
EXPLAIN: The written component of this lab gives students the opportunity to explain the correlation between work and kinetic energy. The collaborative nature of an inquiry based lab also encourages discussion between lab partners.
ELABORATE: Students are asked to suggest ways to improve their procedure in the conclusion of the lab report.
EVALUATE: Have students present their experiments to one another and encourage them to question each other’s techniques. This allows students to self evaluate and recommend improvements to their experimental designs.
What to expect: One common mistake students make during this activity is using the following equation: v = d/t . If they use that equation to find velocity, they will be finding average velocity. Plugging that in to the KE formula gives average KE, which is undesirable, because it doesn’t reflect the KE of the object once work is completed at the bottom of the ramp. This mistake can be prevented by circulating during the lab and having students explain how they collected and used data. When they tell which velocity equation they used, ask them to point to the spot on the ramp where work is complete and then if that is the velocity
Physics- Unit 5 DRAFT 40 at that point. Most students will realize they made a mistake at that point, and will choose a more appropriate equation. To find the correct values for velocity and KE, students should use the 2 following equations: Δd = vit + ½ at to find the acceleration of the object down 2 2 the ramp, then either a =Δv/t or vf = vi + 2aΔs to find the final velocity. The final velocity can then be used to solve for KE.
Physics- Unit 5 DRAFT 41 Work/Kinetic Energy Lab
Purpose: To design and conduct an experiment to determine the relationship between work and kinetic energy by conducting laboratory experiments.
Allowed materials: meter sticks, stopwatches, steel ball bearings of different sizes, tape, ramps. Other materials must be approved before beginning. You are NOT allowed to use your textbooks. Books will be left in the classroom overnight during this lab.
Requirements: Before beginning, each group must submit a written hypothesis and experimental design. Upon approval, you will conduct at least three trials to obtain data. If, upon analyzing that data, you need to make adjustments to your design, you may then do so. If it becomes apparent that your hypothesis was incorrect, you should continue experimenting until you have proof of a relationship between work and kinetic energy. It is okay if your original hypothesis is incorrect. When you write your lab report, you will have a chance to address your hypothesis as well as any changes that were made to your experiment.
Lab Report: You will be writing a formal report for this assignment. Your report should include the following: 1. Purpose 2. Hypothesis 3. Materials and methods (this needs to be written so that I could hand it out as lab instructions for another class) 4. Data and analysis (all data tables and calculations should go here. You should show graphs of all data) 5. Conclusions a. What is the relationship between work and kinetic energy? b. Was your original hypothesis correct? c. What changes did you make to your procedure after the first trial? Why were those changes necessary? d. What were some sources of error in this lab? e. How could your experimental design have been improved? Think of ways to reduce error.
Physics- Unit 5 DRAFT 42 Teacher notes for Catapult Project
Language (ELP) Objective for LEP Students:
ENGAGE: Show students pictures or video of catapults and trebuchets in action. Then hand out the instruction sheet for the project. Explain to the students that their mission is to create the most efficient catapult or trebuchet in the class. Be sure to discuss proper safety precautions, such as wearing goggles while working with wood, and suggest that students ask a parent or other adult for help if they will be using power tools.
EXPLORE: Use the simulation at http://www.forgefx.com/casestudies/prenticehall/ph/catapult/catapult.htm to allow students to play with the effects that the spring strength, arm length, and release angle have on the horizontal and vertical distances that the projectile travels.
EXPLAIN: The written component of this project gives opportunities for students to explain how catapults and trebuchets were used, as well as to explain the physics behind them both.
ELABORATE: The competition portion of this project provides an opportunity for students to discuss physics concepts in a practical scenario. Facilitate this discussion by asking students to make predictions about the possible improvements to each design. As the competition continues, they should be able to more accurately predict the performance of each catapult.
EVALUATE: The written component of this project provides a way to gauge student understanding. Students are required to analyze each design and discuss ways to improve them. This analysis provides insight into each student’s level of understanding.
Physics- Unit 5 DRAFT 43 Honors Physics Catapult Project
Requirements:
1. Your catapult must be able to launch a tennis ball at least 5 feet horizontally from the starting point. 2. The catapult must be finished and ready to go when you come in to class on the competition date. This means that all parts should be put together, glue should be dry, and you shouldn’t have to do anything to it except place the tennis ball on it and trigger the catapult. Incomplete projects will result in a major loss of points. 3. Points will be deducted if the catapult falls apart after the first launch. 4. No slingshots. You may build a catapult or a trebuchet. 5. Each team will get three trials. We will use the data from the best trial. 6. All catapults must have some sort of trigger mechanism. Using your hand or foot to bend back the arm is not acceptable.
Due Dates:
1. Design: Blueprints with measurements of top/side views. All aspects of the catapult must be labeled and measured to receive the full 10 points. Due ______
2. Catapult Competition: ______We will have three competition categories for extra credit: 1. greatest distance 2. best design (best construction/most original) 3. most efficient design (size vs. distance)
3. Written report: write 1-3 pages on how forces and conservation of energy are demonstrated with a catapult. A bibliography of at least one source needs to be included. This should also include data regarding the competition, analysis of each team’s catapult, and any improvements you would make to your design. Details can be found on the next page. Due ______
Catapults will be graded as follows:
1. Blueprints: worth a total of 10 points. These will be graded based on neatness, accuracy, and design. Blueprints should be clearly labeled, drawn to scale, and should show both the top view and the side view
Physics- Unit 5 DRAFT 44 of the catapult. The trigger mechanism should be clearly labeled, as well as the method of propulsion and the “basket” for the projectile. 2. Construction: worth a total of 20 points. This will be graded based on the execution of your design. Did you follow your blueprints? If not, did you submit revised plans? Is the catapult neatly built? Quality of construction and sloppiness count here! 3. Projectile launch: worth 20 points. This will be graded based on a comparison between the maximum dimension (length, width, or height) of your catapult and the horizontal displacement of the projectile. If your catapult self-destructs after being used, you will lose points here! 20 points: 10x 10 points 4x 15 points: 7x 5 points: 2x 4. Lab Report: worth 50 points. Include background about catapults and similar devices, as well as information about their use throughout history. Discuss how this project relates to the different areas of physics. Be thorough. I can think of at least 5 connections just off the top of my head. Be sure to discuss the energy transformations involved in launching a catapult or trebuchet. Include detailed instructions about the construction of your catapult. These should have enough detail that someone else could build your catapult using your directions. Be sure to include a discussion of why you chose this particular design. 1. Why did you choose these materials? 2. Why did you choose this method of propulsion? 3. Why did you choose this trigger mechanism? Describe the other groups’ catapults, including their propulsion and triggers. Data from the competition, including the efficiency of each catapult. Analysis of the results of the competition. Discuss the reasons why certain designs were more successful than others. How could each design be improved to be more efficient? Explain improvements that could be made to your catapult. Include a sketch. Remember, none of the projects are perfect. They could all be improved!
Physics- Unit 5 DRAFT 45 Assessment Items
1. A student walks 2 m across a level surface at constant velocity carrying a 5N backpack on his back. What is the net work done on the backpack? a. 0 J b. 2.5 J c. 5 J d. 10 J
2. ______is the sum of kinetic energy and all forms of potential energy. a. elastic potential energy c. gravitational potential energy b. kinetic energy d. mechanical energy
3. ______is the type of energy associated with objects in motion. a. elastic potential energy c. gravitational potential energy b. kinetic energy d. mechanical energy
4. A 25 kg crate rests at the top of a 12 m tall hill. What is the crate’s potential energy?
5. A 55 kg student runs at 8.5 m/s. What is his kinetic energy?
6. If a geyser shoots water at a maximum velocity of 12 m/s, what is the maximum height the water will reach?
7. Using the graph below, calculate the work done on the object.
Force v. Distance
5
) 4 N ( 3 e c r 2 o F 1 0 0 1 2 3 4 Distance (m)
Physics- Unit 5 DRAFT 46 8. If the work in problem #7 is done in 5.0 seconds, what is the power? 9. A 40.0 N crate starting at rest is pushed with a force of 35N across a 6.0 m distance. The force of friction between the crate and ground is 6.0 N. Using the work-kinetic energy theorem, find the final velocity of the crate.
10. Discuss the energy transformations involved when a tennis racket hits a tennis ball.
Physics- Unit 5 DRAFT 47 Answers: 1. a. zero work is done because the force is perpendicular to motion 2. d 3. b 4. 2940 J 5. 1987 J 6. 1/2mv2 = mgh since the masses are the same, mass cancels out and ½ (12)2 = 9.8 h 72 = 9.8h H = 7.3 m 7. Work is the area under the graph, so 4 x4 = 16 N*m 8. P = W/t so P = 16/5 = 3.2W 9. 40 = mg so mass is 4.0 kg Fnetd = KEf – KEi since initial velocity is zero, KEi is zero (35-6) x 6 = 1/2(4.0) v2 175 = 2v2 87 = v2 V = 9.3 m/s 10. Answers will vary, but should include the following: the racket and ball initially have kinetic energy, because they are both moving. When they hit, the tennis ball is deformed giving it elastic potential energy which is then converted into kinetic energy as the ball flies away.
Physics- Unit 4 DRAFT 48