Physics HS/Science Unit: 03 Lesson: 01 Suggested Duration: 13 days Kinematics of 1D and 2D Motion Lesson Synopsis: In the last unit, the student gained experience with motion through measurements and graphical techniques. That motion was limited to one dimension and the emphasis was on graphing techniques and interpretation of the graphs. In this unit, the emphasis is again on motion, but the student will be expected to perform calculations involving the motion variables. The student will learn to represent the vector quantities of velocity, acceleration, and displacement with vectors. With these skills, the variables of projectile motion (an important 2D problem) will be resolved. The motion investigated to date is translational or linear motion of a point object. Problems involving uniform circular motion of a point and rotation of a circular object are introduced with similar equations of motion. TEKS: P.4 P.4B P.4C The student knows and applies the laws governing motion in a variety of situations. The student is expected to: Describe and analyze motion in one dimension using equations with the concepts of distance, displacement, speed, average velocity, instantaneous velocity, and acceleration. Readiness Standard Analyze and describe accelerated motion in two dimensions using equations, including projectile and circular examples. Supporting Standard Scientific Process TEKS: P.1 P.1A P.2 P.2E P.2F P.2G P.2H P.2I P.2J P.2K P.2L P.3 P.3F 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: Demonstrate safe practices during field and laboratory investigations. The student uses a systematic approach to answer scientific laboratory and field investigative questions. The student is expected to: 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. Demonstrate the use of course apparatus, equipment, techniques, and procedures, including triple beam balances, slotted and hooked lab masses, ring clamps, ring stands, stopwatches, friction blocks, 90-degree rod clamps, metric rulers, spring scales, meter sticks, scientific calculators, graphing technology, computers, ballistic carts, and other standard laboratory equipment. Use a wide variety of additional course apparatus, equipment, techniques, materials, and procedures as appropriate such as micrometer, caliper, computer, ballistic pendulum, inclined plane, pulley with table clamp, and four inch ring. Make measurements with accuracy and precision and record data using scientific notation and International System (SI) units. Identify and quantify causes and effects of uncertainties in measured data Organize and evaluate data and make inferences from data, including the use of tables, charts, and graphs. 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. Express and manipulate relationships among physical variables quantitatively, including the use of graphs, charts, and equations. The student uses critical thinking and scientific reasoning, and problem solving to make informed decisions within and outside the classroom. The student is expected to: 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. GETTING READY FOR INSTRUCTION Performance Indicator(s): Graphically represent and analyze a problem situation related to projectile motion. Complete a laboratory report that includes the proper use of significant figures and error analysis. (P.2H, P.2J, P.2K; P.4B, P.4C) 1C; 5B, 5G ©2012, TESCCC 06/13/12 page 1 of 17 Physics HS/Science Unit: 03 Lesson: 01 Key Understandings and Guiding Questions: In two dimensional motion, displacement, velocity, and acceleration must be treated as vector quantities. The magnitude angle and component forms of vectors are used in studying these motions. — What are vectors? — What are the vector quantities describing motion? — What are the basic equations describing linear motion? — How are basic kinematics equations used to describe projectile motion? Vocabulary of Instruction: speed displacement SI unit system motion detector vector resultant angular displacement error velocity vector acceleration line graph radian angular velocity centripetal acceleration position average speed uniform circular motion right triangle curve fit vector components Materials: golf ball and super ball Refer to Notes for Teacher section for materials. Attachments: Video: Greatest Slide Stunt Ever Handout: Moving Man Simulation (1 per student) Handout: Projectile Motion Simulation (1 per student) Teacher Resource: Projectile Motion Simulation KEY Handout: Day 2 Kinematics Problems (1 per student) Teacher Resource: Day 2 Kinematics Problems KEY Handout: Equation and Symbol Chart (1 per student) Handout: Significant Digits – Significant Figures (1 per student) Teacher Resource: Significant Digits – Significant Figures KEY Handout: Moving Man Problems (1 per student) Teacher Resource: Moving Man Problems KEY Optional Handout: Unit 03 Homework Assignment (1 per student) Teacher Resource: Unit 03 Homework Assignment KEY Handout: Reliability of Physical Measurements (1 per student) Optional Handout: Using Excel to find the Standard Error (1 per student) Handout: Practice Error Calculations (1 per student) Teacher Resource: Practice Error Calculations KEY Handout: Measuring g with a Motion Detector – Vernier or Pasco specific (1 per student) Handout: Lab Report for Measuring g – Vernier or Pasco specific (1 per student) Teacher Resource: Lab Report for Measuring g KEY – Vernier or Pasco specific World in Motion: e1962 and e1925 Optional World in Motion: 1910 Handout: Projectile Motion (1 per student) Handout: Projectile Motion Lab Report (1 per student) Teacher Resource: Projectile Motion Lab Report KEY Handout: Hit the Cup Project (1 per student) Video: Projectile Motion Full Handout: Vector Tutorial (1 per student) Teacher Resource: Instructor Vector Addition Tutorial Handout: Vector Problem Examples (1 per student) Handout: Acceleration Down a Ramp (1 per student) Handout: Acceleration Down a Ramp Lab Report (1 per student) 2012, TESCCC 06/13/12 page 2 of 17 Physics HS/Science Unit: 03 Lesson: 01 Handout: Acceleration Down a Ramp – Photogate (1 per student) Handout: Acceleration Down a Ramp – Photogate Lab Report (1 per student) Handout: Rotational Motion Notes(1 per student) Handout: Rotational Motion Problems (1 per student) Teacher Resource: Rotational Motion Problems KEY Handout: Rotation Equation and Symbol Chart (1 per student) Handout: Hit the Cup Project Report Teacher Resource: Hit the Cup – Teacher Guide Handout: Unit 03 Review Questions (1 per student) Teacher Resource: Unit 03 Review Questions KEY Resources and References: Ultrasonic motion detector and computer analysis software. Some of the preferred activities utilize ultrasonic motion detectors which can be controlled by graphing calculators or computer. Alternate activities are sometimes given. Pasco or Vernier equipment is described in the lessons. AND/OR Photogates with computer software. An alternate activity is included for Pasco or Vernier photogate equipment. TEA article on significant digits and/or significant figures: http://www.tea.state.tx.us/curriculum/science/aboutsigfig.html Sources of error discussions: http://www.saburchill.com/physics/chap03.html http://level1.physics.dur.ac.uk/skills/erroranalysis.php STATE RESOURCES: Physics Inquiry Project: www.thetrc.org/trc/projects_tcg.html Science TEKS Toolkit: http://www.utdanacenter.org/sciencetoolkit Advance Preparation: 1. Instructional Note: Please check availability of required probeware and all computers for required Pasco or Vernier lab files. Type of software required is specific to classroom computers, probeware, and calculators available for your campus. Software files may be downloaded for free at the respective sites. PASCO and Vernier data files will not open without prior installation of required software. 2. Obtain materials above, and test items to make sure they are working properly. There are various options and alternate laboratories available in this unit. The teacher should take inventory of his/her equipment and decide on which activities will be utilized in this unit. 3. Make certain that the software that is needed is installed and compatible with your computers, networks, and IT personnel. Technology persons often demand significant lead time, and glitches are very common. 4. Students will be graded on laboratory work (participation), a lesson exam, homework, and a project (successful launch of a marble into a cup) with significant weighting of each component. Instruction should be paced for nearly three weeks. 5. Install software needed for the activities on the computers that students will use in the laboratory and for homework. Microsoft Word and Excel Ultrasonic motion detector software or photogate software World-in-Motion (physics toolkit 6.0) software and videos Internet Explorer with plug-ins for showing videos, etc. Either Pasco – Data Studio and/or Vernier – Logger Pro software and appropriate experiment files 6. Practice with the specific software for the motion detector and simulations. 7. Prior to Day 11, the project “Hit the Cup” materials need to be gathered – some of the materials are not standard lab equipment. 8. Edit and copy (potential questions) and other handouts for students. 9. Prepare attachments as necessary. ©2012, TESCCC 06/13/12 page 3 of 17 Physics HS/Science Unit: 03 Lesson: 01 Background Information: In this lesson, the student reviews and extends his/her measurement and presentation skills and learns problem-solving techniques within the context of one- and two-dimensional constant acceleration motion. Kinematics, in large part, does not emphasize what causes the motion but merely attempts to describe that motion. The dynamics of motion (forces, energy, and other motion parameters) are studied in later units. Students learn how to set up and work kinematics problems. The topics of significant digits, unit analysis, metric prefixes, exponential notation, and error analysis are stressed. These are fundamental to success later, but are typically not much fun at the time. Since calculations are a large part of this unit, it is important to instill into the students the value of working problems systematically and in a clear format. The students will need to draw on some of the skills (graphing, report writing, etc.) from the last unit. As in the previous unit, if you do not have the apparatus called for in the activities, you will need to find other approaches to presenting the material. GETTING READY FOR INSTRUCTION SUPPLEMENTAL PLANNING DOCUMENT Instructors are encouraged to supplement, differentiate and substitute resources, materials, and activities to address the needs of learners. The Exemplar Lessons are one approach to teaching and reaching the Performance Indicators and Specificity in the Instructional Focus Document for this unit. A Microsoft Word template for this Planning document is located at www.cscope.us/sup_plan_temp.doc. If a supplement is created electronically, users are encouraged to upload the document to their Lesson Plans as a Lesson Plan Resource for future reference. INSTRUCTIONAL PROCEDURES Instructional Procedures Notes for Teacher ENGAGE – Introduction to Kinematics NOTE: 1 Day = 50 minutes Suggested Day 1 Attachments: Video: Greatest Slide Stunt Ever 1. Show the Video: Greatest Slide Stunt Ever. 2. Explain that the Video: Greatest slide Stunt Ever is faked, but that the physics to perform the stunt is within the capability of the class and is similar to a project they will complete. 3. Announce that for the next three weeks, the class will have another but different look at motion. The use of graphs will continue, but more detail and specific information will be utilized. The name of this unit is “kinematics”. 4. Explain that kinematics is the study of and describing motion using numbers and equations. In kinematics, we ask how fast, how far, and how long did it take type questions relating to motion. 5. Introduce the Hit the Cup project, where they will roll a marble down a ramp and into a cup. The rules of the project will be presented later. . 6. Indicate that they already know some information, but need to learn how to put this information together before they can complete the project and perform calculations on projectiles. 7. Ask questions to show students that they already have significant knowledge. Ask: If you travel 50 mi/hr for 3 hours – how far did you go? Wait for answers, and then add these conditions: In a straight line. (150 miles) In a circle. (0 miles) 1.5 hours each way. (0 miles) ©2012, TESCCC 06/13/12 Instructional Notes: Limit the introduction discussion to 10 minutes to allow the students to have time to interact with the simulations. If necessary, the vector discussion can be conducted at another time. The introduction of the kinematics equations is only necessary to show that there are just a few ideas that are used over and over. Misconceptions: Students may think that acceleration and velocity are always in the same direction. Students may think that an object thrown into the air has zero acceleration at the highest point. Students may think that velocity is a force. page 4 of 17 Physics HS/Science Unit: 03 Lesson: 01 Instructional Procedures Notes for Teacher How did you get the answer? What would the equation be? (d = vav t), where vav is the average velocity If you traveled in a straight line for 150 miles and it took 3 hours, how fast did you drive? (50 mi/hour) What was the average velocity? How did you get the answer? What equation did you use? (vav = d/t ) Is this different from the other equation? Convince students that these are the same equation and that it is easier to remember one equation rather than two, but some thinking is necessary. 8. Remind students that displacement is a vector and it is important to be clear about the real question being asked. Is it distance or displacement? Ask: What do we mean by vector and scalar? Give examples. (Bring out the idea that time is not a vector because forward is not a direction!) In one dimensional motion, how do we designate the direction of a vector? Positive or negative number within a coordinate system 9. Remind students of some of the fine points about vectors and scalars, and give examples of quantities that are vectors and examples of quantities that are scalars. Include discussions of (speedometer, average, instantaneous, and average values). EXPLORE – Introduction to Kinematics Suggested Day 1 (continued) 1. Quickly go over the kinematics equations below which describe motion in 1D for constant acceleration. Just identify the symbols, and stress that these apply for constant acceleration motion like falling objects. These equations are part of the chart handed out tomorrow Δd = vav t 2 Δd = vo t + ½ a t v = vo + a t 2 2 v – vo = 2 a Δd vav = (v + vo)/2 2. Instruct the student to groups run the two simulations. 3. Explain that they will explore two simulations that will be used heavily during the next couple of weeks and they should answer specific questions on the Handout: Moving Man Simulation and the Handout: Projectile Motion Simulation. There will be a post-lab discussion at the end of the period to go over any questions. This document may or may not be turned in for credit. 4. Very briefly demonstrate the moving man simulation. 5. Distribute the Handout: Motion Man Simulation and the Handout: Projectile Motion Simulation. 6. Assist students with the simulations, and answer questions as needed. 7. When there is10 minutes left in class, discuss any problems with the simulations and questions on the handouts. ©2012, TESCCC 06/13/12 Materials: marbles marble launch materials Attachments: Handout: Moving Man Simulation (1 per student) Handout: Projectile Motion Simulation (1 per student) Teacher Resource: Projectile Motion Simulation KEY Instructional Notes: The simulation activities are intended primarily to introduce these specific simulations which will be used later. Do not take up the simulation sheets, but allow students to keep them for informational purposes when they run the simulations later. The projectile motion simulation reinforces that the horizontal motion speed remains constant. page 5 of 17 Physics HS/Science Unit: 03 Lesson: 01 Instructional Procedures Notes for Teacher 8. Stress that there are only two significant digits for time and up to three for acceleration, velocity, and displacement on the moving man simulation. (This concept may or may not have much meaning at this point.) 9. Stress that the horizontal motion on the projectile motion is the (d = vav t) equation, where v is constant and d is the distance coordinate. So, half of the projectile motion problem is already solved. EXPLAIN – Working Physics Problems 1. Ask: 2 If a car starts from rest and accelerates at 5 m/sec for 6.0 seconds, how far did it travel and how fast was it moving at the end of the 6.0 seconds? 90m at 30m/sec 2 How is this problem worked? d = v0t + ½(5)(6) = 90m; v = v0 + (5)(6) = 30 m/sec Emphasize that it is not the answer, but the technique, that is being requested. That is what today is about. 2. Distribute the Handout: Day 2 Kinematics Problems. These are to be worked in class and handed in today. They will be critiqued and returned tomorrow. The problem above is the first of the problems on this sheet. Students are to work all problems. 3. Lead a discussion on how the problems should be solved and presented in class. Use this problem as an example. A common approach has the following steps. More or less steps can be required. Read the problem once or twice to get a general idea of what is being asked. You may want to read it several times for this purpose. Not understanding the problem is the most common source of error. Include any assumptions not clearly stated. Write down the information in symbol form, and write down what is being asked in symbol form with a question mark or blank to emphasize that when this blank is filled, the problem is solved. Ensure all of the quantities are in proper (SI) units. Sketch the motion. For now, this is a necessary step to assure that the problem is properly understood. Later, it may not be necessary for all problems. Visualize the motion in your head. Write down equations that describe this motion (from the five equations on the handout), and determine a strategy about which equation to use. Narrow down choices to an equation with a single unknown and the other symbols known. If the equation being used can solve for the unknown easily, solve the equation for the unknown algebraically. Isolate the unknown on the left side of the equation by itself, with the known quantities on the other side. Insert the numbers, and perform the calculations with a calculator. Repeat as needed until all of the question parts have been answered. Check to make sure that the answers have the proper units and significant figures. (At this point, do not have the students worry about the significant digits, which will be discussed later. Now, just have them focus on doing the problem correctly.) Suggested Day 2 Attachments: Handout: Day 2 Kinematics Problems (1 per student) Teacher Resource: Day 2 Kinematics Problems KEY Handout: Equation and Symbol Chart (1 per student) Instructional Notes: Today is the day to look at how physics problems are solved. It is largely a technique intensive day. At the end of the day, students will have worked a few problems using proper technique, including the appropriate units. Students will have started an equation sheet (many instructors allow this sheet to be used with tests). Some problems will be worked in class and then turned in so that you may evaluate the technique of students. These problems and your critique (including a trial grading scheme) will be handed back and discussed tomorrow. It is suggested that a wrong multiplication or non-logic mistake produces only a slight loss of grade. Although these are standard formulas for physics, they need to correlate with STAAR Reference Materials used by students on assessment. 4. For this specific problem, the motion is 1D with v and x being requested, vo and t are given. The motion is straight line, and the equations are the ©2012, TESCCC 06/13/12 page 6 of 17 Physics HS/Science Unit: 03 Lesson: 01 Instructional Procedures Notes for Teacher constant acceleration motion equations. Thus, the information and unknown lines might look like: v = _____ m/sec 2 d = _____ m 1. Δd = vo t + ½ a t vo = 0 2. v = vo + a t v = (0 + 5.0 * 6) = 30 m/sec 2 2 a = 5.0 m 3. v – vo = 2 a Δd t = 6.0 sec 4. vav = (v + vo)/2 5. It should be clear that equation 2 gives the value of v and equation 1 gives the value of d. The number of significant digits is two and should eventually be reflected in the answers (discussed later) which could be placed in the blanks. Do not give full credit unless all of the important steps are followed. 6. For the second problem, ask the class to direct your hand in working the problem according the method outlined above. 7. Divide the students into pairs, or small groups, and have them work the remaining problems and turn in before the end of the class. These are for you to critique. 8. If time permits, you should have the students start a symbol-equation sheet. The Handout: Equation and Symbol Chart is a good start and should be distributed to the students. EXPLAIN – Significant Digits 1. Hand back the student problems worked in class yesterday, and describe to the class what is needed to do better. Explain any comments placed on the student papers. 2. Announce to the class that today will emphasize problem solving of constant acceleration kinematics problems, but with attention to the number of significant digits in the information and in the answers. 3. Make a brief presentation on significant digits, and indicate your policy on how they are to be used. Also, indicate what penalty (partial credit removed from a correct answer) is applied if they are not handled correctly on homework and test answers. (Specific decisions are left up to the teacher.) 4. Use the problems handed back as examples of how to handle the significant digits, and have the students correct their answers according to your policy. 5. Break students into small work groups, and hand out problems due tomorrow, but with a clear directive that there should be time to finish the assignment in class today. The Handout: Moving Man Problems would be appropriate for this assignment. 6. If the students need the help, do the first problem or two as a class discussion. It is instructive to check the answers with the moving man simulation either as a demonstration or in student groups. If Internet access and time is available for the students, allow them to check their answers with the moving man simulation. Encourage the students to pay attention to the graphs from the simulation to aid in the understanding. Suggested Day 3 Attachments: Handout: Significant Digits – Significant Figures (1 per student and teacher) Teacher Resource: Significant Digits – Significant Figures KEY Handout: Moving Man Problems (1 per student) Teacher Resource: Moving Man Problems KEY Optional Handout: Unit 03 Homework Assignment (1 per student) Teacher Resource: Unit 03 Homework Assignment KEY Instructional Notes: Although not specifically addressed in current physics standards, the use of Significant Figures is taught in chemistry and used in the field of physics. Today’s goal is to cover the topic of significant digits and continue working kinematics problems. This is done through a review of yesterday’s problems, a discussion and drill on significant digits, and through checking answers using the simulations. The Handout: Significant Digits – ©2012, TESCCC 06/13/12 page 7 of 17 Physics HS/Science Unit: 03 Lesson: 01 Instructional Procedures Notes for Teacher 7. Assist students, and encourage them to stay on task during the class time. Significant Figures is taken from the web, and many other similar documents are available. It is included as a possible aid for the students or for the instructor as a source of ideas. As noted below, the emphasis on significant digits in the classroom is an open question to be answered by the instructor in the room. The Handout: Moving Man Problems can be worked in class and the answers checked by the simulation. Now is a good time to re-emphasize the use of graphs in understanding motion. If the students do not have access to the web, using the moving man simulation as a class activity is also useful. The Handout: Significant Digits – Significant Figures addresses the topic of significant digits and/or significant figures. This TEA article addresses some of the difficulties involved with teaching significant figures. http://www.tea.state.tx.us/curriculum/sci ence/aboutsigfig.html. Most teachers agree on the following: Students should formally know the number of significant digits in different numbers and in different formats. (scientific notation or other) Calculations (because it is so easy) should be carried out with more than the “official” number of significant digits. Students should formally know that the “official” answer contains as many significant digits as the least significant number used in the calculation. Many teachers allow one more than the “official” number of significant digits, with the last digit underlined to designate it as doubtful. EXPLORE/EXPLAIN – Measuring g and Error Analysis 1. Remind students that the unit project is to hit a cup with a projectile and that task requires knowledge of how things fall under the influence of gravity and how precise (accurate) predictions are done. 2. Announce that today the class will measure the acceleration due to gravity and use that data to examine error analysis and how to report measurements. The class will measure the acceleration of gravity using a ©2012, TESCCC 06/13/12 Suggested Day 4 Materials: meter sticks stopwatches golf ball(s) page 8 of 17 Physics HS/Science Unit: 03 Lesson: 01 Instructional Procedures Notes for Teacher “super” ball(s) stopwatch and meter stick. 3. Review a little about bodies falling under the influence of gravity and neglecting air friction. The class will (with help) devise the procedure, estimate the error, improve the technique, and do the error analysis on the measurements. 4. Introduce the topic of reporting measurements and errors. Ask: (5 minutes) If I were to measure the height of a desk and report the value as 85.1 cm ± 0.2 cm, what do these numbers mean? (Value and estimated error) If another person measures the value to be 85.4 cm ± .4 cm, do these measurements agree or disagree? Try to get students to agree that the measurements are compatible. Which is correct? (Both – if correctly stated) Why do we report an error? (It is customary and useful.) If my best measurement of a mass is 2.31 kg and the known mass is 2.40kg, how would I report the measurement? (Percent error) How is percent error figured? % = errors difference (100) standard When do you report percent error and when do you report absolute error? (Depends upon the situation) 5. Lead a brief discussion on reporting error and kinds of error. The Handout: Reliability of Physical Measurements can be used as a reference for the students and should be distributed at this time or a teacher-created document can be substituted. The last page summary will be useful for the students later. Include precision and accuracy terms in your discussion. (10 minutes) 6. Introduce the topic and materials to measure g – the acceleration due to gravity. Ask: Which falls faster a nickel or a golf ball? Does the mass of the object affect the rate of fall? Most classes will correctly say the same rate. Demonstrate the fact anyway that mass is not a factor. 7. Develop a procedure, and measure g as a class – Method I. (15 minutes) Ask: Given the materials (meter sticks, stopwatches, balls), how could we measure the acceleration due to gravity? Let the class brainstorm different ideas. Choose one. Probably someone drops a ball from a known height. Use several timers across the class, etc. Involve as many students as possible in the process. In the process, do not be afraid to throw out obviously bad data. Have fun, and discuss possible errors. Have a student record the times on the board. Ask which student’s time measurement to use? Class will say average. Ask if the class did the process again, will it get the same answer? How close? What is the error value to use? Will we get better with practice? Discuss the role of percent error and data scatter in this measurement. Arrive at some conclusion about the error that should be attached to ©2012, TESCCC 06/13/12 Attachments: Handout: Reliability of Physical Measurements (1 per student) Optional Handout: Using Excel to find the Standard Error (1 per student) Handout: Practice Error Calculations (1 per student) Teacher Resource: Practice Error Calculations KEY Instructional Notes: Like significant digits, the degree to which error analysis is presented is highly dependent upon the goals of the class and background of the students. The information presented in this lesson is probably minimal, but some reference documents are made available if the class goals demand more. In addition, there are a number of good sources of error discussions on the web. Two such websites are: http://www.saburchill.com/physics/chap 03.html and http://level1.physics.dur.ac.uk/skills/erro ranalysis.php The documents provided as reference for the class are: Handout: Reliability of Physical Measurements An overview of error analysis with examples and summary Handout: Practice Error Calculations The complicated standard error calculation is not too bad if Excel functions are used. The information presented for the classroom activities is intended to keep the class involved in a dialogue on error analysis and allow you to assess the skills of the students in making simple measurements. You may not want to emphasize the formal standard error equations and procedure. It is adequate to mention that there is a standard way to present the information. Save the standard error discussion for page 9 of 17 Physics HS/Science Unit: 03 Lesson: 01 Instructional Procedures Notes for Teacher this technique. (Likely 10% or more) 8. Develop an improved procedure, and measure g as a class – Method II. (10 minutes) 9. In Method I, there is uncertainty in when the student (ball dropper) will let the ball drop. This affects the timers. Try to get the dropper(s) out of the error process. Ask if it would be valid to let the ball roll off the edge of a table so that the timers could anticipate the starting time? Ask: If an object is launched sideways at the same height as another object is dropped straight down, which hits the ground first? The class has already found the time of fall to be the same from simulations but may need convincing with videos. Make sure that they understand that the question does NOT ask which goes faster or farther. 10. Illustrate the independence of the vertical and horizontal motion. 11. Show the Video: X and Y Motion, and/or run the simulation of the two balls falling at the URL given here. 12. Measure g using an improved technique, discuss the error sources, and develop a new measured value and error. Hopefully, this value will be more accurate and the data scatter will be less than that from Method I. later, if you want to emphasize that method at all. A good activity to use for this purpose would be to measure the height of a table at different locations by different people, or you may use the data in the Excel Handout: Practice Error Calculations. Video: X and Y Motion http://www.upscale.utoronto.ca/GeneralI nterest/Harrison/Flash/ClassMechanics/ TwoBallsGravity/TwoBallsGravity.html 13. Review class policy on error reporting. 2 14. Indicate that since you have a standard value of g = 9.81 m/sec , giving a percent error or an absolute value is appropriate. However, if you did not have that value, you would need to determine a reasonable value for the error based upon common sense and data scatter. 15. If it fits your class policy, finish the presentation on random errors and the use of standard error in reporting measurements and/or using Excel to calculate the standard error. Most teachers will not require the use of the standard error, but rather use an educated guess at random error in their classroom. 16. Assign as homework or in-class work the Handout: Practice Error Calculations. EXPLORE/EXPLAIN – Measuring g with a Motion Detector 1. Review any questions or leftovers from yesterday in terms of: The importance of g, and when it applies Error analysis in your classroom 2. Tell the students that they will use the motion detector to measure g and will hopefully get a more accurate value than with the stopwatch. One purpose is to confirm that the global value of g applies to your local classroom. 3. Divide the class into normal lab groups, distribute the apparatus and handouts, and perform the laboratory investigation Measuring g with a Motion Detector. Each lab group should hand in one lab report. Emphasize that the error analysis is important, as is explaining error sources such as air friction. ©2012, TESCCC 06/13/12 Suggested Day 5 Materials: basketball or similar object stand to position the motion detector coffee filter alternate* files for “World in Motion” program (if you do not use the motion detector apparatus) Attachments: Handout: Measuring g with a page 10 of 17 Physics HS/Science Unit: 03 Lesson: 01 Instructional Procedures Notes for Teacher 4. Assist the students with the data taking, analysis, and saving the graphs to a Word document. 5. It is likely that students remember how to handle the programs, but they may need reminding. If necessary, remember that the entire screen can be saved (copied) by hitting Ctrl-Print Screen. 6. The program gets slopes through a subtraction of previous data points and then does some smoothing. Thus, the velocity graph tends to be offset from the position graph and so on. The same time portions of the all graphs may not produce the best results. 7. Most classes will not have time to perform the coffee filter portion of the lab, but it may serve as a demonstration topic and introduce free fall, air friction, and parachutes. 10. Perform a post-lab discussion on the experiment and questions at the end of the lab report. 8. It should be clear that the "free fall” motion up after the bounce can also provide a value of g. This motion agrees with the previous study of graphs. 9. The dramatic negative “bounce” acceleration can provide a conversation topic for collisions, and the negative direction should be emphasized – up is negative. 10. Remind students of the homework assignment due on Day 9. EXPLORE – Projectile Motion Concepts 1. If the activities from yesterday are not complete, summarize or otherwise close out that topic. Ask: If a ball rolls off the table at a speed of 2 m/sec and is in the air for 0.15 seconds, how far does it land from the table? Since the d motion is simply d = vot, the class should respond .3 meters. How high is the table? Again, they should answer correctly. 2. Not to be answered, only ask! 0 If the ball left at an angle of 30 , where would it land? (More difficult but farther from the table) At what angle and speed would it need to be shot to hit a target at 1.1 m from the table? (More difficult) 3. Explain that on Day 12, each lab team will roll a ball down a tube and hit a target placed on the floor by the instructor. The team will also provide calculations detailing how they calculated the parameters necessary to be successful. Most will roll the ball horizontally off the table but some may want to launch at an angle. 4. The lab today gives experience with launch speeds and angles. 5. In addition, the knowledge and skills will be tested on the unit exam. 6. Break the class into lab groups, and distribute the Handout: Projectile ©2012, TESCCC 06/13/12 Motion Detector – Vernier or Pasco specific (1 per student) Handout: Lab Report for Measuring g – Vernier or Pasco specific (1 per student) Teacher Resource: Lab Report for Measuring g KEY – Vernier or Pasco specific World in Motion: e1962 and e1925 Optional - World in Motion: 1910 Instructional Notes: While it is suggested that the motion detector apparatus be used, similar concepts can be presented using the “World in Motion” program and video “e1962” for the falling ball with bounce and “e1925” for a body falling with extreme air friction. Students should remember how to use the motion detector and computer to report data, but may need a review. This is a standard activity and is presented to enhance the student’s laboratory skills. It should also give some reality to the 2 idea that g really is 9.8 m/sec and that measurement error really does exist. Suggested Day 6 Attachments: Handout: Projectile Motion (1 per student) Handout: Projectile Motion Lab Report (1 per student) Teacher Resource: Projectile Motion Lab Report KEY Handout: Hit the Cup Project (1 per student) Instructional Notes: One goal for today is to remind students about “hit the cup” project and generate some enthusiasm for learning about vectors and projectile motion. The Walter-Fendt projectile motion simulation works well and can be used by students to check homework problems. By now the students have familiarity with the basic kinematics equations for one dimension and recognize that 2D motion is more complicated. They also have an appreciation for vectors, but are probably not proficient in their use. This page 11 of 17 Physics HS/Science Unit: 03 Lesson: 01 Instructional Procedures Notes for Teacher Motion. Remind students that the x and y motions are independent and that this program splits up the total motion into x and y motions using vector techniques. The class will study these techniques more tomorrow. Send the students to the computers to run the simulation found at http://www.walter-fendt.de/ph14e/projectile.htm. 7. Assist the students in setting up the simulation and filling out the data sheet using Handout: Projectile Motion Lab Report. 8. Continue with the lab exercises to the end of the period or until you decide a lecture is called for based upon student questions. 9. Encourage the students to read the material carefully. 10. Each student should keep a separate lab report which will be discussed tomorrow. class period is used to discuss rules for the project, discuss what things must be learned, and to get a start on the learning about projectile motion through a simulation program. If your students are not familiar with the use of scientific or graphing calculators to find the sine and cosine of angles, a few minutes should be taken just handling the mechanics of punching in numbers. The right triangle logic will be covered tomorrow. The simulation activity requires calculations with sines and cosines. The meaning is not needed explicitly today. 11. Distribute the Handout: Hit the Cup Project to the students at the end of the class so they may begin to think about it. They will be expected to devise a procedure on Day 11 then perform the task on Day 12. EXPLAIN – Working with Vectors 1. Ask: Name some vectors and some scalar quantities. Force, velocity, etc.; time, mass, etc. Who uses vectors in their work? (Pilots, engineers, architects, graphic artists) 2. Explain that today is dedicated to developing vectors formally. They will use vectors on the project and also in later chapters. There are also vector problems on the pending homework assignment. There will be some inclass group work on vectors, and if not completed today, they should be worked at home and handed in tomorrow. 3. Lead a discussion similar to that found in the Teacher Resource: Instructor Vector Addition Tutorial. Present numerous examples to illustrate the equations and stress the skills needed. 4. Provide the URLs from the tutorial or other study sources. 5. Provide the Handout: Vector Tutorial. 6. Have the students work the example problems in small groups, and go over these as additional examples as time permits. If the students are not finished with these problems, they should take them home and hand in tomorrow. ©2012, TESCCC 06/13/12 Suggested Day 7 Attachments: Handout: Vector Tutorial (1 per student) Teacher Resource: Instructor Vector Addition Tutorial Handout: Vector Problem Examples (1 per student) Instructional Notes: Today’s goal is to introduce vectors formally in 2 and 3 dimensions. Quickly limit the discussion to 2 dimensions, and then look at: vector addition graphically, vector conversion between magnitude angle format and the component formulation, and vector addition in components. From the projectile motion activities, the students should be aware of the usefulness of breaking the vectors into components and have a feel for the process. The students should also be aware that vectors will be useful in analyzing the motion of the “marble” down the ramp used to launch the projectile in the project. Today, formally present vector theory, and work through some examples. Determine the background of your students, and tailor your presentation accordingly. page 12 of 17 Physics HS/Science Unit: 03 Lesson: 01 Instructional Procedures EXPLAIN – Working Homework, Getting It Clear Notes for Teacher 1. This session should not be a “teacher works the problem and students copy it from the board” session. A variety of presenters and student participation is recommended. 2. Determine where the students are in the homework assignment and what is causing the most trouble. 3. Use the period to help the students get the homework ready to turn in and understand the wide range of problems. 4. One possible approach would be for the teacher to work one problem – emphasizing techniques then this could be followed by the class “directing the teacher’s hand” for a problem and followed by a student being at the board and the class directing the hand of the student presenter. Suggested Day 8 Instructional Notes: The goal for today is to help the students to understand and be able to complete the homework that is due tomorrow. Problems like those on the homework have been introduced and practiced at times earlier, but now a variety of different types of problems are now all due at the same time. This creates some pressure. In addition, the correct method of working the problems has been stressed and the students need to know that this is still an important part of the procedure. 5. The idea is to keep the students involved. 6. An alternative approach is to pair the students and have each pair work a different problem on the board during the first half of class. Then, they’ll present their work, round robin style, the second half of class. 7. Tomorrow, the lab activity is to measure the acceleration due to gravity (g) by measuring the acceleration down a ramp and applying vector concepts to obtain g. Spending some time on a problem resembling this situation would set the stage for that lab activity. EXPLORE/EXPLAIN – Acceleration Down a Ramp 1. Ask: Which will take longer? Falling off the height of a ramp or rolling down the ramp? (It takes longer to roll down the ramp.) Will the time depend upon the slope of the ramp? (Yes) 2. After taking up homework and answering any last minute questions, inform the class that today you are going to measure the acceleration due to gravity by measuring the acceleration of a cart down a ramp. This will give them some practice and experience with vectors. Develop ramp concepts – 5 min 3. Arrange for two cart track setups to be at the front of the room for some preliminary demonstrations. Ask questions, then demonstrate the answers of the different situations running side-by-side races down the ramps. The starting technique for the races is very important. A ruler, blocking the start, then quickly removed works well. Ask: If we have a steep ramp and one not so steep, which cart will win the race? (Which accelerates more?) Steep If we have an empty cart and a loaded (heavy) cart, which will win the race? They are mostly the same. 0 What would be the acceleration if the ramp was at a 90 angle? (g 2 – 9.8 m/sec ) Can we use vector components to find g by measuring the acceleration down the ramp? Yes, this is the point of the lab. It typically takes much longer to work problems as a class than anticipated, so spend some time inquiring about where the students are and what concepts are giving students difficulties. Concentrate the class time on the areas of difficulty. Work those specific homework problems or problems of that type. Suggested Day 9 Materials: stopwatch protractor meter stick cart and track motion detector apparatus Attachments: Handout: Acceleration Down a Ramp (1 per student) Handout: Acceleration Down a Ramp Lab Report (1 per student) Handout: Acceleration Down a Ramp – Photogate (1 per student) Handout: Acceleration Down a Ramp – Photogate Lab Report (1 per student) Instructional Notes: The standard lab activity utilizes motion detectors but there is a version for photogates using a picket fence and software. The ramp demonstration races need to be set up and ready for class. ©2012, TESCCC 06/13/12 page 13 of 17 Physics HS/Science Unit: 03 Lesson: 01 Instructional Procedures Notes for Teacher Develop the equations for the lab – 5 min Make sure that the apparatus, including the computer software and motion detector apparatus or photogates, is available. Students should be proficient with the apparatus, but may need some additional help. 4. Show the students the diagram of the apparatus, and go through the equations needed in the lab to understand the use of vectors to find g. Indicate that one report per group is needed. Perform the lab activity with post-lab – 40 min 5. Divide the class into lab groups, provide the following handouts and start lab. Handout: Handout: Handout: Handout: student) Acceleration Down a Ramp (1 per student) Acceleration Down a Ramp Lab Report (1 per student) Acceleration Down a Ramp – Photogate (1 per student) Acceleration Down a Ramp – Photogate Lab Report (1 per This activity gives useful practice now for when Newton’s laws are examined. The normal force concept will be easier if the student has had the experiences gathered today. 6. Assist students as needed. 7. Perform a post-lab discussion. There should be time to do both parts of the lab, but the post-lab is more important than completing both methods. If even one group completes the motion detector portion of the lab, the results from that group can be discussed. 8. Stress that breaking the motion into components (perpendicular) is important, the motion down the ramp is constant acceleration, and the motion normal to the ramp is zero. Ask: How might friction affect the results? Slow down – g measure small Which measurement approach is better? Could be either, if the technique is good EXPLORE/EXPLAIN – Rotational Motion Concepts 1. Explain that today the class looks at rotational or circular motion. So far in the course, the motion has been that of a point, or a point in an object, traveling in a straight line or (for projectile motion a combination of straight line motions). That motion is referred to as translational motion, and now we study rotational motion. Ask: What are some things that rotate or move in circles? Tires, planets, CDs, pulleys, rolling balls Which objects rotate and translate? Tires and rolling balls What is the relationship between the number of rotations and the linear distance rolled? With more turns, the farther the distance The rotational speed and the linear speed? The faster the rotational speed, the faster the linear speed. Most students will have a qualitative idea, but may not have formal equations. That will be covered later. If the disk rolls through 1 rotation across a desk, how far has it traveled on the desk? 2πr Is this the same as the circumference? Yes What are some of the words that describe circular or rotational motion? Answers may vary, but include angle, rotation, etc. ©2012, TESCCC 06/13/12 Suggested Days 10 and 11 Materials: demonstration wheel (with reference line) Attachments: Handout: Rotational Motion Notes (1 per student) Handout: Rotational Motion Problems (1 per student) Teacher Resource: Rotational Motion Problems KEY Instructional Notes: Today is basically a lecture-discussiondemonstration day to develop the concepts and equations of uniform rotational motion. The students will have ideas about this topic, but will need formal guidance and vocabulary page 14 of 17 Physics HS/Science Unit: 03 Lesson: 01 Instructional Procedures Notes for Teacher 2. Announce that they are going to look at strictly rotational motion first and then look at the connection between rotational motion and the motion of moving wheel a little later. Have the two URLs below readily available. discipline. Since rotational motion will be studied later in connection with Newton’s laws and satellite motion, the goal is to develop vocabulary, concepts, and some kinematics equations. 3. Bring up the Ladybug simulation: http://phet.colorado.edu/simulations/sims.php?sim=Ladybug_Revolution http://www.upscale.utoronto.ca/GeneralInterest/Harrison/Flash/ClassMech anics/RollingDisc/RollingDisc.html 4. Present the concepts and equations for this topic. Students should be encouraged to add these equations and concepts to their “equation and symbol chart”. The URL of hyperphysics has good resources for this topic under rotational motion. http://hyperphysics.phy-astr.gsu.edu/HBASE/hframe.html 5. If time permits, assign selected questions from the “rotational motion” problems to work in class. It is unlikely that there will be time, and you should use the first half of class tomorrow for that task. 6. Inform the students that questions like these will be on the unit exam. A large disk with a line visible on the side as a reference which can roll on the desk or in the air helps demonstrate some of the ideas. In addition, you should have the Phet Ladybug simulation opened on an Internet connection with classroom display. This simulation can clarify some of the concepts efficiently. In the discussion, try to use terms such as linear speed and angular speed to connect the angular concepts to the related linear concepts in the student’s minds. 7. Ask the students if they have any questions before they continue working on the assignment. 8. Divide the students into groups to work together, or send students to the board in groups, to report their results to the class or work the problems as a group. 9. The question on orbital motion (#7) should be discussed, as it ties several concepts together that are classic confusion points for students. ELABORATE – Hit the Cup Suggested Day 11 (continued) Performance Indicator Graphically represent and analyze a problem situation related to projectile motion. Complete a laboratory report that includes the proper use of significant figures and error analysis. (P.2H, P.2J, P.2K; P.4B, P.4C) 1C; 5B, 5G 1. View the video: Project Projectile Full to introduce the activity, and if needed, redistribute the Handout: Hit the Cup Project. 2. Allow students to practice with the materials but stipulate that tomorrow the cup will be placed at a specified location and they must adapt to that location. They will then be expected to hit the cup from their procedure and calculations. If possible, leave the equipment set up for tomorrow to save time. Assist students with their equipment and in developing a procedure, but inform them that they are expected to have the procedure in place at the beginning of class. Materials: stand and clamps to hold projectile ramp marbles projectile ramps (tubing)and tape to hold them in place meter stick washer and string as plumb line Attachments: Video: Project Projectile Full Handout: Rotation Equation and Symbol Chart (1 per student) Handout: Hit the Cup Project (1 per student) Handout: Hit the Cup Project Report Teacher Resource: Hit the Cup Teacher Guide Instructional Notes: ©2012, TESCCC 06/13/12 page 15 of 17 Physics HS/Science Unit: 03 Lesson: 01 Instructional Procedures Notes for Teacher Working rotational motion problems and preparing for the “Hit the Cup” Project: Reserve 20 minutes at the end of class to prepare for the Hit the Cup project performance which will take place tomorrow. It is assumed that the lecture demonstration on uniform rotational motion did not leave time to complete the in-class problem set. The first part of class is dedicated to completing thoughts on that subject, allowing students additional time to work the problem set, and to discuss some of those problems in class. Project Projectile Full Video: This brief introduction into rotational kinematics will be helpful to understand topics to be visited later and should not be neglected. Adding these equations and concepts to the equation sheet is recommended. A separate Handout: Rotation Equation and Symbol Chart is included as an example. The goal for the second half of class is for the groups to do all that is necessary to be successful in the hit the cup “presentation” tomorrow. EVALUATE – Hit the Cup Suggested Days 12 and 13 1. This should be a fun day as student groups show off their skills. 2. Have each group take their opportunity with the “Hit the Cup” activity. 3. Instruct each student to complete a laboratory report over the “Hit the Cup” activity. 4. Distribute copies of the Handout: Unit 03 Review to the students. Materials: stand and clamps (to hold projectile ramp) marbles projectile ramps and tape (to hold in place) meter stick washer and string (as plumb line) stop watches Attachments: Handout: Unit 03 Review Questions (1 per student) Teacher Resource: Unit 03 Review Questions KEY Instructional Notes: The room arrangements will dictate the real conditions for the “presentations”, but having each student group perform ©2012, TESCCC 06/13/12 page 16 of 17 Physics HS/Science Unit: 03 Lesson: 01 Instructional Procedures Notes for Teacher their project in an order determined by a random draw is a possibility. Each group could be given the target range for their projectile and the materials. The groups would be given 10–15 minutes to perform calculations and prepare their set up. Following this preparation time, no further calculations or adjustments would be allowed without some penalty. The groups then perform in rotation. Suggestions for assigning range distances and other elements of the project are discussed in the Hit the Cup Teacher Guide document. ©2012, TESCCC 06/13/12 page 17 of 17