- Brief Description of Manual Activities
- Running a Workshop
- Organization of Section II – Newton’s Second Law: Activities and Understanding
- Organization of Section III – Newton’s Second Law: Problem Solving and Situation Analysis
- Materials and Equipment List
- Equipment List by Activity
- Equipment Sources and Construction Notes
- Software and Software Settings
- Selected Bibliography
Section I. : Introduction, Materials, and Bibliography
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Published:2013
Robert A. Morse, 2013. "Introduction, Materials, and Bibliography", Teaching About Newton’s Second Law: An AAPT/PTRA Teacher Resource Guide, Robert A. Morse
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The activities in this resource guide will develop the ideas of Newton’s second law and Newton’s first law through use of microcomputer-based laboratory (MBL) techniques, in a teaching sequence developed by Robert Morse, Maxine Willis, Priscilla Laws, David Sokoloff, and Ron Thornton. Similar teaching sequences are currently available in published curricula including Workshop Physics, Real-Time Physics, and the CPU project Force and Motion unit. This resource guide includes two major sections. Section II reviews one-dimensional kinematics using microcomputer-based laboratory techniques, then works through a series of experimental activities that develop the basis of Newton’s second and first laws. Finally students use Newton’s laws in activities that develop several specific force laws. By the end of Section II, students have finished a set of activities that are the experimental evidence for a Newtonian model of motion in one dimension. In Section III, students look at the use of the mathematical descriptions of Newton’s laws, the force laws, and kinematics for problem solving, i.e., the analysis of physical situations using the mathematical models developed in Section II.
1. Brief Description of Manual Activities
The activities in this resource guide will develop the ideas of Newton’s second law and Newton’s first law through use of microcomputer-based laboratory (MBL) techniques, in a teaching sequence developed by Robert Morse, Maxine Willis, Priscilla Laws, David Sokoloff, and Ron Thornton. Similar teaching sequences are currently available in published curricula including Workshop Physics, Real-Time Physics, and the CPU project Force and Motion unit. This resource guide includes two major sections. Section II reviews one-dimensional kinematics using microcomputer-based laboratory techniques, then works through a series of experimental activities that develop the basis of Newton’s second and first laws. Finally students use Newton’s laws in activities that develop several specific force laws. By the end of Section II, students have finished a set of activities that are the experimental evidence for a Newtonian model of motion in one dimension. In Section III, students look at the use of the mathematical descriptions of Newton’s laws, the force laws, and kinematics for problem solving, i.e., the analysis of physical situations using the mathematical models developed in Section II.
2. Running a Workshop
The activities in this manual should be just about right for two to five six-hour days. If teachers are already familiar with MBL and are familiar with the AAPT/PTRA resource Teaching About Kinematics (Nelson & Nelson, AAPT, 2009), then the remaining activities could perhaps be done in two days. A more leisurely pace would be better for those who are new to physics teaching or to the use of microcomputer-based laboratory techniques.
Introduction
The introduction, discussion of rationale, materials, logistics, etc. may take half an hour to an hour. The materials discussion could be broken up into parts or deferred, but participants often worry about materials, so it may help to have this discussion first. If participants are going to build the equipment themselves, then with a little prefabrication of parts, the equipment could be assembled and tested in one morning.
The learning sequence is broken up into two main parts. The first part (Section II) consists of activities to build an understanding of Newton’s second law and to determine the behavior of six common forces. The second part (Section III) provides a framework for teaching some aspects of problem solving using Newton’s second law.
Section II (Activities) can be done in one fast day for experienced teachers and leaders, but would be better done at a slower pace. There is enough material in the activities and discussion of them to spend a day and a half to two days on this part. Section III (Problem Solving) could be done in a fast half day, but would be better done in a whole day or longer with time to practice the techniques. There are some laboratory practical activities included at the end of Section III.
The next several pages contain an outline of the activities and major headings in Section II and Section III in more detail than the table of contents. The outlines are followed by a discussion of materials and equipment needed for the various activities. Depending on the time and inclinations of the instructors and the resourcefulness of the teachers, construction of equipment could be done as a pre-activity to the workshop, as a post-activity, or left to the teachers. An effort has been made to keep the construction of equipment as inexpensive and simple as possible, but to have equipment that will work and stand up to reasonable service in the classroom.
3. Organization of Section II – Newton’s Second Law: Activities and Understanding
Introduction
Technology
Microcomputer-Based Laboratory Equipment Video Analysis and Simulations
Kinematics of One-Dimensional Motion
Participants should do this activity to become familiar with the interface hardware and software and review the use of MBL for kinematics. This activity could be abbreviated or left out for teachers who are already familiar with MBL use. About an hour is needed as a review, more if participants are new to MBL activities.
Activities 1-6. Review of Motion Measurements with the Motion Detector
Activity 1. Measuring Position and Velocity
Activity 2. Position Matching
Activity 3. Velocity Matching
Activity 4. Fast and Slow Electric Cars
Activity 5. Measuring Velocity & Acceleration
Activity 6. Motion with a Fan Cart
Activities 1-6. Definitions
Activities 1-6. Discussion:
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Language of graphs
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Relationships among graphs and variables
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Using motion detectors
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Electric constant speed cars
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Fan cart use techniques
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Techniques
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Graph setups
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Dynamics of One-Dimensional Motion
Activities 7-12. Force and Motion – Newton’s Second Law
Activity 7. Measuring Forces
Participants should do this activity to establish familiarity with the force probe. 20 minutes.
Activity 7. Discussion:
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Conceptual idea of force
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Calibration of a force probe
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Low-tech alternative
Activity 8. What Connects Motion and Force?
This is the central activity in which participants “discover” that force causes acceleration. It takes very little time to do, but participants should be led through a discussion of the implications of their observations. About 15 minutes.
Activity 8. Discussion:
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Technique
Activity 9. Acceleration-Force and Velocity-Force Graphs
This activity follows up and reinforces the conclusions from Activity 8. About 15-20 minutes.
Activity 9: Discussion:
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The relation of force and motion and the effect of mass
Activity 10. Motion with a Constant Force
Depending on time this can be done as in interactive demonstration, and teachers might choose to do it that way in the classroom. It is worthwhile for participants to carry out the activity so that they have the practice. It should take about 15 to 20 minutes.
Activity 10. Discussion:
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Force exerted by a single fan unit
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Low-tech alternative
Activity 11. Combinations of Forces and Masses
Combining forces
Adding more “stuff”
Because this activity uses multiple fan units, it is probably best taught as an interactive demonstration. For a workshop, it and Activity 12 can be done first as a demonstration, and then participants can have the chance to repeat the experimental parts for themselves, so they get the practice in handling the multiple fan units. About an hour to an hour and a half.
Activity 11. Discussion:
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Multiple forces exerted on a constant mass
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Forces exerted on multiple masses
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An optional extension to the mass experiment
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Low-tech alternative
Activity 12. Dueling Fan Units
This may also be done as an interactive demonstration, but again, participants will need to first see it done and then practice it themselves. About 20 minutes.
Part 1: Combining Forces
Part 2: Motion with Counteracting Forces
Activity 12. Discussion:
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Forces exerted in different directions.
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Motion when the combination of forces is zero.
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“Push-me Pull-you” fan cart activity
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Representing forces on free-body diagrams
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Low-tech alternative
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Force Laws
Activities 13-17. Finding Force Laws
Activity 13. The Force Law for a Spring – Hooke’s Law (Activity or Interactive Demonstration)
This activity should be followed by a discussion. About half an hour.
Activity 13. Discussion:
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Developing force laws
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The elastic force law (Hooke’s law)
Activity 14. Local Gravitational Force Law
This may be done as an activity followed by discussion or as an interactive demonstration. About half an hour.
Activity 14. Discussion:
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The local gravitational force law
Activity 15. Air Drag
Activity 15. Discussion
Activity 16. Normal and Tension Forces
Activity 16. Discussion
Activity 17. Sliding Friction
Activity 17. Discussion:
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Force of kinetic friction
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Low-tech alternative
Activity 18. Sliding to a Halt on Level Surface
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4. Organization of Section III – Newton’s Second Law: Problem Solving and Situation Analysis
Role of Newton’s Second Law
Role of Newton’s First Law
Role of Newton’s Third Law
A Collection of Force Laws
Elastic force
Local gravitational force
Tension force
Interactions between solid surfaces
Normal force
Frictional forces
Fluid drag force
Other forces
List of force law equations
Newton’s Law Problem Solving – Overview
Knowledge organization for problem solving with Newton’s second law
Types of Problems
Force Law Problems
Basic Second Law Problems
Kinematics Combined with Basic Second Law Problems
Simple Force Law and Basic Second Law Problems
First Law Force Combination Problems
General Second Law Problems
Problem Solving Tools: Free-Body Diagrams
Problem Solving Tools: Free-Body and Component Diagrams
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Free-body diagram exercises
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Tricks of the Trade: Multiple Objects – Trading Diagrams for Algebra
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Evaluating special cases
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Extending/generalizing
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Tricks of the Trade: Situation Analysis: Many Problems into One
Tricks of the Trade: Bending the Universe
Tricks of the Trade: Turn One Problem into Many
Motivating Demonstrations with Problem Solving
Appendix – Formal Problem Solving in Kinematics
A five-day sequence of class and homework to develop organized problem analysis and solution.
Derive the equations for motion with constant acceleration
Day 1 – Representing the problem
Day 2 – Corrections, choice of equation, and algebraic solution
Day 3 – Corrections, substitution, computation, and checks
Day 4 – Corrections and revision
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Advantages of this method
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Transition to textbook problem solving
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Moving to dynamics problems
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References
Graphical Derivation of equations for constant acceleration
Formal Problem Solving: Kinematics Problems Part 1
Formal Problem Solving: Kinematics Part 2: Equations and Algebra
Formal Problem Solving: Kinematics Part 3: Substitution, Computation and Checks
Formal Problem Grading: Standards Teaching
5. Materials and Equipment List
This manual is designed to be computer-intensive, using microcomputer-based laboratory techniques. It was developed using Vernier Software’s LabPro Interface and LoggerPro Software. All experiments can also be done using PASCO lab interfaces with DataStudio Software.
MBL equipment: (for one-lab station)
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Macintosh or Windows PC
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PASCO or Vernier software package
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PASCO or Vernier laboratory interface
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Ultrasonic motion detector
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Force sensor able to be mounted on PASCO or Vernier dynamics cart
Other equipment: (for one-lab station, see source and construction notes)
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Constant motion car
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Two to three PASCO, Vernier, or other low-friction carts
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Fan unit: homemade or PASCO or Vernier (minimum one per station)
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PASCO 2.2 meter track or equivalent
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Four AA cells for each fan unit (NiCad rechargeable or Alkaline)
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One dummy cell for each fan unit (5.0 cm length of 1/2 inch diameter aluminum rod)
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Rubber bands
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10 N spring scale
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20 N spring scale
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Craft stick – to make motion detector target on cart
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Duct tape
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Four large binder clips – to fasten fan units together
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String or yarn to make loop – about 20 cm
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Large paper clip – to make tow hook for cart
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Springs – at least two different with force constants in the range of about 10 N/m to 100 N/m [can be made by cutting “snaky” (not “Slinky”) wave spring to various lengths]
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Three or four 500 g masses with hooks to hang on spring scale
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Thread – about 1 meter
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Crisp graham crackers
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Strip of plastic with hole in one end—to pull through index card for friction activity
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Index card for friction activity
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5 by 5 cm square of fine sandpaper for friction activity
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Optional: “push-me pull-you” controller and modified fan units for its use (see below)
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Optional: gear motor for friction experiment (Activity 17)
Safety equipment
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Goggles or safety glasses, cheap cotton gloves
The use of fan units involves propellers rotating at high speed. Students should wear some form of eye protection, and the students who are catching the fan units should wear cheap cotton gloves to prevent possible cuts from the propeller blades.
6. Equipment List by Activity
With few exceptions, all activities require a computer, a laboratory interface, a motion detector, and a force probe for each lab group. In addition, a low-friction cart, a fan unit, batteries for the fan unit, and a track for the cart to run on are needed for many activities. Duct tape is used to fasten homemade fan units to carts. It is convenient to have the same setup for the instructor. The list below only indicates materials needed in addition to this basic setup. Specifications and sources for the equipment are given below.
Activity 1. Measuring Position and Velocity, Activity 2. Position Match, Activity 3. Velocity Match |
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Activity 4. Fast and Slow Electric Cars |
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Activity 5. Measuring Velocity and Acceleration, Activity 6. Motion with a Fan Cart, Activity 7. Measuring Forces |
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Activity 8. What Connects Motion and Force? Activity 9. Acceleration-Force and Velocity-Force Graphs |
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Activity 10. Motion with a Constant Force |
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Activity 11. Combinations of Forces and Masses |
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Activity 12. Dueling Fan Units |
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Activity 13. The Force Law for a Spring – Hooke’s Law (Activity or Interactive Demonstration) |
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Activity 14. The Local Gravitational Force Law |
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Activity 15. Air Drag |
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Activity 16. Normal and Tension Forces |
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Activity 17. Sliding Friction |
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Activity 18. Sliding to a Halt on a Level Surface |
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Activity 1. Measuring Position and Velocity, Activity 2. Position Match, Activity 3. Velocity Match |
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Activity 4. Fast and Slow Electric Cars |
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Activity 5. Measuring Velocity and Acceleration, Activity 6. Motion with a Fan Cart, Activity 7. Measuring Forces |
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Activity 8. What Connects Motion and Force? Activity 9. Acceleration-Force and Velocity-Force Graphs |
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Activity 10. Motion with a Constant Force |
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Activity 11. Combinations of Forces and Masses |
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Activity 12. Dueling Fan Units |
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Activity 13. The Force Law for a Spring – Hooke’s Law (Activity or Interactive Demonstration) |
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Activity 14. The Local Gravitational Force Law |
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Activity 15. Air Drag |
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Activity 16. Normal and Tension Forces |
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Activity 17. Sliding Friction |
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Activity 18. Sliding to a Halt on a Level Surface |
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7. Equipment Sources and Construction Notes
Note that some sources and prices may have changed (web links current in 2012, unless otherwise noted).
PASCO scientific, PO Box 619011, 10101 Foothills Blvd., Roseville CA 95678-9011; 800-772-8700, fax: 916-786-8905, sales: [email protected]; www.pasco.com PASCO sells the low-friction dynamics carts, 2.2 m track and ready-made fan units. Also has computer interface systems (Science Workshop and PasPort), software (Data Studio) and force probes and motion detectors. Vernier Software & Technology,13979 SW Millikan Way, Beaverton, OR 97005-2886; 503-277-2299, fax: 503-277-2440, sales: [email protected]; www.vernier.com Vernier sells LabPro and ULI laboratory interfaces, motion detectors, force probes, and the LoggerPro software package. Recently began selling low-friction carts and tracks also. Most of the activities in this manual also could be done using the older MacMotion software for the Macintosh computer. Check the online catalog for information. | |
Constant motion car: Arbor Scientific (arborsci.com), PASCO, Physics Toolbox (physicstoolboxinc.com), and other suppliers for about $6 to $8 each. Larger quantities have been purchased from Westminster, Inc., www.westminsterinc.com, 800-241-9378, as item 0004 Antenna Tumble Buggy in boxes of 48 units, or from Kipp Brothers, Inc., www.kipptoys.com, 800-428-1153. | Car is 18 cm long, 10 cm wide, 8 cm tall. It runs on two C-cells in series. With two freshly charged NiCad C-cells, it travels at about 0.33 m/s. With one C-cell and a 5-cm dummy cell cut from a length of 1/2-inch diameter aluminum rod, it travels at 0.15 m/s. It can also run at about the same speed using AA cells instead of the C-cells—you just need to put in a piece of material to support the AA cells in place. (Wrap AA cell in cardboard strip or short piece of 3/4-inch PVC pipe to make diameter larger.) (Alternative dummy cells: A. length of 0.5-inch diameter wood dowel wrapped in heavy aluminum foil, or B. Drilled through length with roofing nail hammered in each end so nails touch in middle, or C. Old, thoroughly dead AA cell with wrap of heavy aluminum foil.) |
Low-friction carts: | This workshop was designed to use the PASCO ME-9454 Collision cart and easily can be modified to use the less expensive and lower mass PASCO ME-6950 PAScar or ME-6951 GO-car. Vernier dynamics carts (Cart-S or Cart-P) also work well. Other carts may not be suitable. |
Fan units: | The PASCO fan accessory (ME-9491) clips onto the PASCO cart. It comes with two dummy cells and and requires no assembly. Individual units cost about $60 each. Homemade fan units are much cheaper but require construction, which takes time. Construction details are given below for two versions—the original design that was the basis for the PASCO fan unit and a more recent design using a ducted fan used in model airplanes. The first version is cheaper (about $10 each) but takes more construction work. Its description follows. The second, a ducted fan version, is much easier to assemble, but costs about $15 each. Its description begins on p. 20. |
A: Homemade fan unit, showing base, switch bracket, switch, motor mount, and motor with propeller B: Base, switch bracket, switch, and battery holder inside C: Motor and mount, switch bracket with hole for switch |
PASCO scientific, PO Box 619011, 10101 Foothills Blvd., Roseville CA 95678-9011; 800-772-8700, fax: 916-786-8905, sales: [email protected]; www.pasco.com PASCO sells the low-friction dynamics carts, 2.2 m track and ready-made fan units. Also has computer interface systems (Science Workshop and PasPort), software (Data Studio) and force probes and motion detectors. Vernier Software & Technology,13979 SW Millikan Way, Beaverton, OR 97005-2886; 503-277-2299, fax: 503-277-2440, sales: [email protected]; www.vernier.com Vernier sells LabPro and ULI laboratory interfaces, motion detectors, force probes, and the LoggerPro software package. Recently began selling low-friction carts and tracks also. Most of the activities in this manual also could be done using the older MacMotion software for the Macintosh computer. Check the online catalog for information. | |
Constant motion car: Arbor Scientific (arborsci.com), PASCO, Physics Toolbox (physicstoolboxinc.com), and other suppliers for about $6 to $8 each. Larger quantities have been purchased from Westminster, Inc., www.westminsterinc.com, 800-241-9378, as item 0004 Antenna Tumble Buggy in boxes of 48 units, or from Kipp Brothers, Inc., www.kipptoys.com, 800-428-1153. | Car is 18 cm long, 10 cm wide, 8 cm tall. It runs on two C-cells in series. With two freshly charged NiCad C-cells, it travels at about 0.33 m/s. With one C-cell and a 5-cm dummy cell cut from a length of 1/2-inch diameter aluminum rod, it travels at 0.15 m/s. It can also run at about the same speed using AA cells instead of the C-cells—you just need to put in a piece of material to support the AA cells in place. (Wrap AA cell in cardboard strip or short piece of 3/4-inch PVC pipe to make diameter larger.) (Alternative dummy cells: A. length of 0.5-inch diameter wood dowel wrapped in heavy aluminum foil, or B. Drilled through length with roofing nail hammered in each end so nails touch in middle, or C. Old, thoroughly dead AA cell with wrap of heavy aluminum foil.) |
Low-friction carts: | This workshop was designed to use the PASCO ME-9454 Collision cart and easily can be modified to use the less expensive and lower mass PASCO ME-6950 PAScar or ME-6951 GO-car. Vernier dynamics carts (Cart-S or Cart-P) also work well. Other carts may not be suitable. |
Fan units: | The PASCO fan accessory (ME-9491) clips onto the PASCO cart. It comes with two dummy cells and and requires no assembly. Individual units cost about $60 each. Homemade fan units are much cheaper but require construction, which takes time. Construction details are given below for two versions—the original design that was the basis for the PASCO fan unit and a more recent design using a ducted fan used in model airplanes. The first version is cheaper (about $10 each) but takes more construction work. Its description follows. The second, a ducted fan version, is much easier to assemble, but costs about $15 each. Its description begins on p. 20. |
A: Homemade fan unit, showing base, switch bracket, switch, motor mount, and motor with propeller B: Base, switch bracket, switch, and battery holder inside C: Motor and mount, switch bracket with hole for switch |
Pictures of Fan Unit Equipment
Homemade Fan Unit – Overview – Detailed Source List
The first version of a homemade fan unit costs about $10 in parts depending on quantities. It is built on a 2.5-inch long PVC base section cut from PVC down spout. A 5/32-inch hole is drilled in the top face to fasten a motor clip to the top surface with a #10 by 1/2-inch panhead sheet metal screw.
A 1-inch long PVC switch bracket is also cut from the down spout. A 9/16-inch hole is drilled in the center of the top face of the switch bracket to accommodate the push-button switch. The bottom face is cut off the bracket and the bracket is fastened with PVC cement to the base as shown with a 1.25-inch overlap.
A battery holder is fastened to the underside of the top surface of the base section using a 2-inch strip of double-sided foam tape.
The motor is press fit into the clip. The red lead from the motor is soldered to the red lead from the battery holder. The black lead of the battery holder and the blue lead from the motor are soldered to the switch. (Optional: a normally closed mini phone jack is wired in series with the switch to provide for a “remote controller.” See section on “push-me pull-you” controller below.)
The propeller is drilled out with a 9/64-inch or 5/32-inch hole to accommodate a press fit motor T-bushing. The bushing is inserted from the perforated face of the propeller hub and may need to be glued in place. The propeller and bushing assembly is then press fit onto the shaft of the motor, with the solid face of the propeller hub toward the motor. Whiteout or white paint on the end of the propeller make it easier to keep fingers out of its path.
Modifications – See section on “Push-me Pull-you” fan cart controller below.
Detailed Construction Hints
Cut PVC down spout for base (2.5-inch long) and switch bracket (1-inch long) by hand using fine-toothed wood saw or hacksaw, or on 10-inch table saw using plywood blade for large-scale production (wear Safety Goggles!). For 10-20 units it is simplest to cut by hand.
Drill holes with electric drill at modest speed setting. Feed drill slowly into plastic so it does not “grab” the material. A small drill press makes this easier. “Bullet™” drill bits from Black and Decker have centering feature that allows drilling into plastic without the bit sliding on the surface.
Enlarge the hole in propeller slightly for the T-bushing using the existing hole as a guide. Clamp the propeller or use a small drill press vice to hold it while drilling a 9/64-inch (tight) or 5/32-inch (loose) hole. Tap bushing into tight hole with hammer, or glue it into loose hole with hot melt gun or other glue. The bushing is inserted from the perforated face of the propeller hub. Painting tips of propeller blades white with paint or whiteout allows them to be seen more readily when running.
Drill switch mounting hole in center of one face of 1-inch PVC down spout section. Be careful drilling the large hole for the switch. Clamp the face to a wood backing block to prevent it catching on the drill bit. Size the bit to the switch you use. A Forstner bit makes a clean cut without catching, but a spade bit or twist drill can be used.
Glue switch bracket in place as shown with PVC cement—clamp each joint for about 5 minutes using the medium binder clips. (Less durable alternative—fasten in place with double-sided carpet tape.)
Attach motor mount with sheet metal screw from underside. Fasten switch in place. If needed, clean underside of PVC and backside of battery holder with rubbing alcohol. When dry, use two strips of double-sided foam tape to tape battery holder in place under top of the base, with batteries running perpendicular to the motor shaft, and wire leads coming out of the switch end of the fan unit. (A length of dental floss or thin nylon string tied to motor mount and pressed between cells and holder makes removing cells easier—be careful not to let it get wound up on motor shaft.)
Test motor and prop hookup before soldering leads. Press fit prop onto motor shaft with solid face of hub toward motor. (It makes a difference.) Test polarity to make sure prop functions to push the unit. Tin motor leads with soldering gun. Solder leads to switch and to battery holder lead.
Tape 5 cm wide by 6.5 cm long piece of corrugated cardboard to the bottom surface of the fan unit so that the cardboard rests between the rails on the PASCO cart to keep it aligned with the cart. You may then fasten the fan unit to the cart with duct tape. Alternatively, to take advantage of mounting holes on a PASCO low-friction cart, drill four holes in bottom face of the base and cardboard. Use a 13/64-inch drill to allow some slop for the 10 by 32 machine screws that fit the holes on the PASCO cart. Locate holes 15 mm either side of center line of base and 22 mm from front and back edges of base.
Dummy cell is 5 cm long piece of half-inch aluminum rod, used to replace AA cell to reduce voltage of battery pack depending on battery choice. See battery notes below.
Parts and Sources
(Price for single items – discounts available for large orders – pricing and links mostly current in 2012.)
Motor | Radio Shack – 273-223 1.5-3 V dc motor, about $2.30 each. Science Source – High Torque motor #21418, $2. This may be the best source. www.thesciencesource.com (Sept. 2012) 1-800-299-5469 (The Science Source motors are better than the Radio Shack ones – they are rated at 3-6 V, better made and last longer.) |
Propeller | Cox Hobby Distributors – 5-inch diameter 3P (5D3P) right-handed black nylon # 858, about $4 or less in bulk; (877-269-9235, PO Box 274, Penrose, CO 81240) or from model airplane hobby shop—(search web for Cox Hobbies) (Note: choice of propeller was fairly carefully made to provide maximum thrust with the motors—propellers for rubber band models will not work well, as they are designed for much lower rpm.) |
Battery holder | Radio Shack – 270-391, $2.20 Mouser Electronics – 12BH348-GR, $1.20 each (less in bulk) www.mouser.com; 800-346-6873 |
Switch | Radio Shack – 275-1565 push on/push off switch, $3.70 or 275-011, $2.20 or 275-617, $3.70 Mouser Electronics – 103-1023, $1.12 each (less in bulk). |
Base | Genova Products – 2.5-inch length cut from 10-foot length of Genova RainGo PVC down spout RW200, about $12 (Other brands are different size and have too thin a wall.) Call Genova (810-744-4500, 7034 East Court St., PO Box 309, Davison, MI 48423; www.genovaproducts.com) for nearest store or they will ship via UPS a 10-foot length of down spout cut into 5-foot or 2.5-foot pieces. |
Clip for motor | Genova Products – 3/4-inch tubing hanger part # 521071 in bags of 10 or 25 from builder supply, plumbing supply, or direct from Genova Products, cost about $0.15 per clip Science Source – Alternate clip available from Science Source, #21424 pkg. of 10 for $2.50; www.thesciencesource.com; 1-800-299-5469 |
Mounting screw for motor clip and switch plate | 1/2–inch #10 Phillips pan head sheet metal screw from a hardware store |
Motor T-bushing for propeller | Science Source – #21542 package of 20, $5.10; www.thesciencesource.com; 1-800-299-5469 |
Double-sided tape | 3M brand 4008, part No: 051131-06439 1/8-inch thick by 1 inch wide, or Manco, or other brand. |
Mounting for multiple fan units | With one unit mounted on cart with tape or mounting screw, fasten two more fan units front and back with medium binder clips to central unit, turning side units on their side as shown. This dispenses with need for wing unit. See drawing below: |
Alternate method | “Wing” unit for mounting multiple fan units thin wood, plastic, doubled over corrugated cardboard, corrugated plastic, or foam core poster board. Cross piece 35 cm by 7.0 cm, base piece 13 cm by 5.0 cm. Wing crosses base about 2 cm from one end. For corrugated plastic or cardboard, cut 35 cm by 14 cm piece with corrugations parallel to long axis—fold in half along long axis and tape joint to make wing. Tape in place with duct tape. Fasten wing unit to PASCO cart using mounting holes in top of the cart and a 10 by 32 machine screw or just use duct tape. Fasten fan units to wing using medium binder clips from office supply store. wing unit, top view |
“Wing” mounting unit for PASCO fan units | Three PASCO fan units can be mounted on a cart by building a triangular cross-section cardboard beam fastened together with duct tape and held on a cart by a rubber band. The beam should be 30 cm long, with sides of 3.5 cm and a base of 2.3 cm. See picture and diagram below (PASCO now sells a multifan bracket ME-6616). Cardboard beam on cart held with one rubber band. Beam with one PASCO fan unit mounted and room for two more. (R.A. Morse photo) Beam with one PASCO fan unit mounted and room for two more. (R.A. Morse photo) |
Batteries |
Radio Shack – various batteries and rechargers, and battery testers. Other sources for NiCad rechargeable and chargers: Mouser Electronics – 639-CHG-6P four-cell charger $22, 800-346-6873; www.mouser.com Herbach and Rademan –18 Canal St., PO Box 122, Bristol, PA 19007; 800-848-8001; www.herbach.com |
Dummy AA cell | Used in constant speed buggy to reduce speed by replacing one of the cells. (Wrap in cardboard to match diameter of C cell.) Can also be used to reduce the thrust of the fan unit in order to get more variation of force.
|
Coffee filters | Basket-type coffee filters, about 4-inch diameter. One box provides filters for many experiments. |
Thread | Ordinary cotton or polyester sewing thread. Used to break in tension experiment. |
Graham crackers | Any brand. Must be fresh and brittle to make brittle table in normal force experiment. |
Bricks or wood blocks | Used to support ends of Graham cracker table. (Clean new bricks wrapped in duct tape or contact paper make a nice set of supports for many laboratory experiments. The duct tape or contact paper keeps them from crumbling.) |
Weights for tension force and normal force | The weights that come with PASCO carts come in 500-gram mass with the original carts or in 250-gram mass for the PAScar and GOcar. Duct tape a heavy paper clip or loop of string to make masses for hanging. Stack them on the Graham cracker table for table-breaking experiment. |
Gear motor for friction lab (optional) | Herbach and Rademan sells a variety of motors. A low rpm DC gearhead motor such as Buehler #127K25790 costs about $20. A wooden drum with a diameter of about 4.0 to 8.0 cm can be press fit on the shaft, and the motor with a variable DC power supply can be used to tow a force probe along a track for friction experiments. (You can simply tow the probe by hand, but it is harder to keep a constant speed); www.herbach.com |
Motor | Radio Shack – 273-223 1.5-3 V dc motor, about $2.30 each. Science Source – High Torque motor #21418, $2. This may be the best source. www.thesciencesource.com (Sept. 2012) 1-800-299-5469 (The Science Source motors are better than the Radio Shack ones – they are rated at 3-6 V, better made and last longer.) |
Propeller | Cox Hobby Distributors – 5-inch diameter 3P (5D3P) right-handed black nylon # 858, about $4 or less in bulk; (877-269-9235, PO Box 274, Penrose, CO 81240) or from model airplane hobby shop—(search web for Cox Hobbies) (Note: choice of propeller was fairly carefully made to provide maximum thrust with the motors—propellers for rubber band models will not work well, as they are designed for much lower rpm.) |
Battery holder | Radio Shack – 270-391, $2.20 Mouser Electronics – 12BH348-GR, $1.20 each (less in bulk) www.mouser.com; 800-346-6873 |
Switch | Radio Shack – 275-1565 push on/push off switch, $3.70 or 275-011, $2.20 or 275-617, $3.70 Mouser Electronics – 103-1023, $1.12 each (less in bulk). |
Base | Genova Products – 2.5-inch length cut from 10-foot length of Genova RainGo PVC down spout RW200, about $12 (Other brands are different size and have too thin a wall.) Call Genova (810-744-4500, 7034 East Court St., PO Box 309, Davison, MI 48423; www.genovaproducts.com) for nearest store or they will ship via UPS a 10-foot length of down spout cut into 5-foot or 2.5-foot pieces. |
Clip for motor | Genova Products – 3/4-inch tubing hanger part # 521071 in bags of 10 or 25 from builder supply, plumbing supply, or direct from Genova Products, cost about $0.15 per clip Science Source – Alternate clip available from Science Source, #21424 pkg. of 10 for $2.50; www.thesciencesource.com; 1-800-299-5469 |
Mounting screw for motor clip and switch plate | 1/2–inch #10 Phillips pan head sheet metal screw from a hardware store |
Motor T-bushing for propeller | Science Source – #21542 package of 20, $5.10; www.thesciencesource.com; 1-800-299-5469 |
Double-sided tape | 3M brand 4008, part No: 051131-06439 1/8-inch thick by 1 inch wide, or Manco, or other brand. |
Mounting for multiple fan units | With one unit mounted on cart with tape or mounting screw, fasten two more fan units front and back with medium binder clips to central unit, turning side units on their side as shown. This dispenses with need for wing unit. See drawing below: |
Alternate method | “Wing” unit for mounting multiple fan units thin wood, plastic, doubled over corrugated cardboard, corrugated plastic, or foam core poster board. Cross piece 35 cm by 7.0 cm, base piece 13 cm by 5.0 cm. Wing crosses base about 2 cm from one end. For corrugated plastic or cardboard, cut 35 cm by 14 cm piece with corrugations parallel to long axis—fold in half along long axis and tape joint to make wing. Tape in place with duct tape. Fasten wing unit to PASCO cart using mounting holes in top of the cart and a 10 by 32 machine screw or just use duct tape. Fasten fan units to wing using medium binder clips from office supply store. wing unit, top view |
“Wing” mounting unit for PASCO fan units | Three PASCO fan units can be mounted on a cart by building a triangular cross-section cardboard beam fastened together with duct tape and held on a cart by a rubber band. The beam should be 30 cm long, with sides of 3.5 cm and a base of 2.3 cm. See picture and diagram below (PASCO now sells a multifan bracket ME-6616). Cardboard beam on cart held with one rubber band. Beam with one PASCO fan unit mounted and room for two more. (R.A. Morse photo) Beam with one PASCO fan unit mounted and room for two more. (R.A. Morse photo) |
Batteries |
Radio Shack – various batteries and rechargers, and battery testers. Other sources for NiCad rechargeable and chargers: Mouser Electronics – 639-CHG-6P four-cell charger $22, 800-346-6873; www.mouser.com Herbach and Rademan –18 Canal St., PO Box 122, Bristol, PA 19007; 800-848-8001; www.herbach.com |
Dummy AA cell | Used in constant speed buggy to reduce speed by replacing one of the cells. (Wrap in cardboard to match diameter of C cell.) Can also be used to reduce the thrust of the fan unit in order to get more variation of force.
|
Coffee filters | Basket-type coffee filters, about 4-inch diameter. One box provides filters for many experiments. |
Thread | Ordinary cotton or polyester sewing thread. Used to break in tension experiment. |
Graham crackers | Any brand. Must be fresh and brittle to make brittle table in normal force experiment. |
Bricks or wood blocks | Used to support ends of Graham cracker table. (Clean new bricks wrapped in duct tape or contact paper make a nice set of supports for many laboratory experiments. The duct tape or contact paper keeps them from crumbling.) |
Weights for tension force and normal force | The weights that come with PASCO carts come in 500-gram mass with the original carts or in 250-gram mass for the PAScar and GOcar. Duct tape a heavy paper clip or loop of string to make masses for hanging. Stack them on the Graham cracker table for table-breaking experiment. |
Gear motor for friction lab (optional) | Herbach and Rademan sells a variety of motors. A low rpm DC gearhead motor such as Buehler #127K25790 costs about $20. A wooden drum with a diameter of about 4.0 to 8.0 cm can be press fit on the shaft, and the motor with a variable DC power supply can be used to tow a force probe along a track for friction experiments. (You can simply tow the probe by hand, but it is harder to keep a constant speed); www.herbach.com |
Fan Unit Version Two – Construction with Ducted Fan
This second version uses an electric ducted fan intended for model airplane use. It costs more for parts and is less robust, but is lighter and easier to assemble than version one.
Parts list
Ducted fan: GWS-EDF-50 Electric Ducted Fan. From hobby shops or websites. List price between $10 and $20. May be found for less on sale or by bulk purchase. Some sources: www.bphobbies.com, www.hobbyking.com/hobbycity/store/, www.aeromicro.com/Catalog/ducted_fan_systems_108649_products.htm (Sept. 2012)
Battery case with switch: Radio Shack – 270-409 ($2.30)
Mouser Electronics – Part number 12BH348/CS holds 4 AA cells and has a built-in slide switch, $1.55 each. Cheaper in bulk. www.mouser.com (Sept. 2012)
Double-sided mounting tape or carpet tape
Duct tape
Two wooden skewers or thin dowels: about 1/8-inch diameter about 9 inches long.
Corrugated plastic: From craft stores. 20 inch by 30 inch piece about $4.00. You may substitute corrugated cardboard cut from a cardboard box, but it is less durable.
Utility knife or compass cutter or 52 mm (2 and 1/16 inch) hole saw: (2 and 1/8 inch hole saw is easier to find— wrap ducted fan with duct tape to fit larger hole.)
Construction details
Cut 5.0 cm by 5.5 cm piece of corrugated plastic, with corrugations running along the short axis.
Cut two 5 cm strips of mounting tape.
Center the corrugated strip on the bottom of the battery case and mount it with corrugations paralleling the battery alignment. This serves to locate the battery holder on top of a low-friction PASCO cart. (Other carts may require a different mounting system.)
Cut a 7.5 cm by 18 cm piece of corrugated plastic or cardboard with corrugations running parallel to the short axis. Cut two 5.2 cm diameter holes centered 3.5 cm from each end using a utility knife or a compass cutter (available at craft or art supply store) or for large numbers, a 52 mm (2 and 1/16 inch) diameter hole saw. Crease the center on two corrugations to fold up with a 3 cm base. Pop the ducted fan unit into the holes as shown in the diagrams and pictures on the next page.
Mounting for ducted fan.
Corrugated cardboard or plastic, 7.5 cm wide, 18 cm long.
Corrugations run short way Two 5.2 cm (2 1/16 inch) holes on center-line
– centered 3.5 cm from ends.
Crease and fold on corrugations to make 3 cm base section.
Cut two 6.0 cm strips of mounting tape. Stick them to the bottom of the corrugated plastic and ducted fan assembly.
Mount the plastic and fan assembly on top of the battery case with corrugations running perpendicular to the battery alignment. Make sure you do not obstruct the switch. The fan blades should be farthest from the switch. See assembled fan unit diagram below left.
Solder the battery pack leads to the fan leads, or use connectors of your choice. For a remote switch you will need some kind of connector to allow you to break the circuit or a remote power source and switch. You may use a closed-circuit two-conductor phone jack as in the “push-me pull-you” modification of the first version (see pp. 22–23). Mount the jack in an upper corner of the fan holder by drilling a hole through the corrugated plastic or cardboard. See directions and parts in next section. This also allows use of a timed switch, such as the one sold by PASCO.
Fasten the fan unit to the cart with two strips of duct tape. You may gang three fan units together by using two wooden skewers passed through the corrugations on the plastic on the tops of the three battery cases. A rubber band around the ends of the skewers where they stick out of the sides of the outside fan unit corrugations will keep the fan units from sliding off.
“Push-me Pull-you” Fan Cart Controller
A push-button controller lets a demonstrator or students apply forces from opposing homemade or commercial fan units to a low-friction cart and observe the motion with none, one, or both forces exerted. Demonstrator or students keep the cart moving back and forth, and students fill in worksheets showing force, acceleration, and velocity vectors. (See Section II, Activity 12.)
Sketch of the apparatus.
“Push-me Pull-you” fan setups. (R.A. Morse photos)
Description
Addition of a closed-circuit type 3.5-mm phone jack (Radio Shack 274-246, Mouser 16PJ135) to home-made fan units such as those described above, allows two such fan units to be mounted in opposition on a PASCO low-friction cart and controlled by a simple two-button control box.
Part’s list
2 fan units
1 PASCO low-friction cart
1 PASCO track or homemade track for cart
2 two-conductor 3.5-mm phone jacks closed circuit type Radio Shack 274-246 or Mouser Electronics 16PJ135
2 SPST momentary contact push-button switches Radio Shack 275-646 or Mouser Electronics 10PA005
2 six-ft mini phone plugs to wire end cable (Radio Shack) or Mouser Electronics 172-2103
1 plastic project box 3 by 2 by 1 Radio Shack 270-1801
Construction
Drill holes in the homemade fan units to mount the closed-circuit phone jacks (hole size depends on jack used). Cut the wire connection for the positive motor lead and connect the wires to the closed-circuit jack. (Note: there are three connectors on the jack. One lead goes to the solder lug that connects the inner conductor on the plug. The other lead connects to the remaining two lugs on the jack.)
Drill holes for switches in top of project box (hole size determined by switch diameter).
Solder leads from the phone plug cords to the switches. Notch edge of box so that the leads will be lightly clamped when the top is in place. Label the buttons and plugs.
Operation
Secure fan units to cart so they oppose each other. With the plugs inserted in the jacks on the fan units, the buttons will allow the fans to be turned on and off.
Start cart at one end of the track. Use buttons to control the motion so that the cart moves back and forth on the track without hitting the ends. (Support the wires so they do not drag on the cart.)
8. Software and Software Settings
Microcomputer-based laboratory data collection software
There is a variety of different hardware and software available for microcomputer-based laboratory experiments. To try all the possible combinations and test these activities with them would be impossible. All of the activities were developed using Vernier Software LabPro interfaces and LoggerPro 2.1 software (www.vernier.com). All the activities also can be done using PASCO DataStudio software with one of its interface sets (www.pasco.com). (Sept. 2012 – Activities are supported by current versions of the interface software.) Other hardware and software combinations may be suitable. The essential ability required is to measure motion and force variables simultaneously with a force detector that can be fastened onto a cart.
Because of the variety of software and the rate at which new software is introduced, I have included below a list of settings for the principal features of the data collection. Individuals will have to set up templates for their own particular combination of hardware and software. Since most of these setups are based on standard motion and force templates, much of the work can be done by taking a setup that comes with the software, modifying the parameters, and saving the template.
Since detailed information on the use of the software comes with the software, and since other AAPT/ PTRA manuals address specific software and hardware interfaces, I will not duplicate that information. Workshop leaders should make sure participants have access to the needed information for their software interface.
Display sizing of graph setups
Students (and some teachers) have a tendency to get rid of the text window and/or data columns and spread out the width of the graphs to cover the whole width of the computer screen. This is not good! By keeping the graph width down, there is a reasonable ratio of graph height to graph width, making it possible to distinguish and compare slopes, and see contrasts between values of the vertical coordinates. This is lost if the graphs are over wide compared to their height. Ideally, the height of a graph should be about equal to its width. The limited size of the computer screen makes that difficult if you also wish to keep the horizontal axes (time axes in most of the graphs) aligned for easy comparison of events at the exact same time. An additional benefit of keeping the graph window taller than it is wide is that the graphs then print out neatly in the usual vertical format of the paper. Keep your graph windows under control!
Description of software settings
All activities that use MBL equipment use either an ultrasonic motion detector, a force probe, or both.
All graphs in a display are arranged vertically, one above the other, with common time axes.
All graphs are set for manual scaling, not automatic scaling. In some activities, students will be expected to adjust the scales after collecting data. Since appropriate scale settings in a given laboratory activity will depend on force available from fan units and masses of low-friction carts, fan units, and cart-mounted force probes, the preset ranges for the values may need to be modified for particular classroom conditions. I suggest that you try all activities in advance and save setups with the correct ranges for your situation.
All data in these activities are collected and displayed in real time.
Direction away from motion sensor is positive unless otherwise specified.
Derivative specifies number of points used to find slopes to obtain the value of the derivative, i.e., to calculate a velocity value from position-time data. Too few points may give “jumpy” graphs but too many may smooth over details of motion. Depending on your equipment and software, you may need to experiment with the sampling rate and derivative settings to give a usable display.
Measurement and display setup for activities
The following information provides typical interface and display setups for activities in Section II. Saving these setups so students can simply open the software setup for a specific activity helps students concentrate on the physics and not the equipment. Some activities have students modify the setup so that they learn to use some of the many features of the software. Each setup has a code for the file. Thus N2L01, for example, stands for Newton’s Second Law – Activity 1. All activities in this manual will use real-time collection and display of data. Each setup specification lists the type of sensor (e.g., motion or force), the graphs that appear on the setup (e.g., position vs time or acceleration vs force), the limits on the vertical and horizontal axes (e.g., 0 m to 4 m for position and 0 s to 10 s for time), and the sampling rate, derivative, and averaging settings as described above.
N2L01 | Measuring position and velocity | ||||
sensors | graphs | range | sampling | 20 Hz | |
MOTION | pos-time | 0 to 4 m | derivative | 7 pts | |
vel-time | -2 to +2 m/s | averaging | off | ||
0 to 10 s | |||||
N2L02 | Position matching | ||||
sensors | graphs | range | sampling | 20 Hz | |
MOTION | pos-time | 0 to 3 m | derivative | 7 pts | |
0 to 10 s | averaging | off | |||
Match data: pieced line (1 m, 0 s)-(1 m, 1 s)-(2.5 m, 4 s)-(2.5 m, 6 s)-(1.75 m,7.5 s)-(1.75 m, 10 s) | |||||
N2L03 | Velocity matching | ||||
sensors | graphs | range | sampling | 20 Hz | |
MOTION | vel-time | -1.0 to +1.0 m/s | derivative | 7 pts | |
0 to 10 s | averaging | off | |||
Match data: pieced line (0 m/s,0 s) − (0 m/s,2 s) − (0.5 m/s,2.01 s) − (0.5 m/s,4 s) − (0 m/s,4.01 s) − (0 m/s,7 s) − (-0.5 m/s,7.01 s) − ( -0.5 m/s,9.99 s) − (0 m/s,10 s) | |||||
N2L04 | Fast and slow electric cars | ||||
sensors | graphs | range | sampling | 20 Hz | |
MOTION | pos-time | 0 to 4 m | derivative | 7 pts | |
vel-time | -2 to +2 m/s | averaging | off | ||
0 to 10 s | |||||
N2L05 | Measuring velocity and acceleration | ||||
sensors | graphs | range | sampling | 40 Hz | |
MOTION | vel-time | -2 to +2 m/s | derivative | 7 pts | |
acc-time | -4 to +4 m/s/s | averaging | off | ||
0 to 5 s | |||||
N2L06 | Position, velocity, acceleration of fan-driven cart | ||||
sensors | graphs | range | sampling | 40 Hz | |
MOTION | pos-time | 0 to 2.5 m | derivative | 7 pts | |
vel-time | -2 to +2 m/s | averaging | off | ||
acc-time | -1 to +1 m/s/s | ||||
0 to 5 s | |||||
N2L07 | Measuring forces | ||||
sensors | graphs | range | sampling | 40 Hz | |
FORCE | force-time | -10 to 10 N | derivative | 7 pts | |
0 to 30 s | averaging | off | |||
N2L08 | What connects motion and force? | ||||
sensors | graphs | range | sampling | 30 Hz | |
MOTION | vel-time | -2 to +2 m/s | derivative | 7 pts | |
FORCE | force-time | -8 to +8 N | averaging | off | |
acc-time | -10 to +10 m/s/s | ||||
0 to 5 s | |||||
N2L09 | Acceleration-force and velocity-force graphs | ||||
sensors | graphs | range | sampling | 40 Hz | |
MOTION | vel-force | -2 to +2 m/s | derivative | 7 pts | |
FORCE | acc-force | -8 to +8 m/s/s | averaging | off | |
-10 to +10 N | |||||
0 to 10 s | |||||
N2L10 | Motion with a constant force | ||||
sensors | graphs | range | sampling | 30 Hz | |
MOTION | vel-time | -1 to +4 m/s | derivative | 7 pts | |
FORCE | force-time | -0.6 to +0.6 N | averaging | off | |
acc-time | -0.5 to +2 m/s/s | ||||
0 to 5 s | |||||
N2L11 | Combinations of forces and masses | ||||
sensors | graphs | range | sampling | 30 Hz | |
MOTION | vel-time | 0 to 2 m/s | derivative | 7 pts | |
0 to 5 s | averaging | off | |||
N2L12 | Dueling fan units | ||||
sensors | graphs | range | sampling | 30 Hz | |
MOTION | vel-time | 0 to 2 m/s | derivative | 7 pts | |
0 to 5 s | averaging | off | |||
N2L13 | Elastic force | ||||
sensors | graphs | range | sampling | 40 Hz | |
FORCE | force-extension | 0 to 10 N | derivative | 7 pts | |
MOTION | -0.2 to +1 m | averaging | off | ||
position is defined as positive, variable called “extension” is defined as equal to -1 * “position” motion detector placed so cart moves toward it, extension and force zeroed at start of each run. | |||||
N2L15 | Air resistance | ||||
sensors | graphs | range | sampling | 40 Hz | |
MOTION | pos-time | 0 to +3 m | derivative | 7 pts | |
0 to 10 s | |||||
N2L17 | Frictional force | ||||
sensors | graphs | range | sampling | 40 Hz | |
FORCE | force-time | -1 to 10 N | derivative | 7 pts | |
0 to 30 s | averaging | off | |||
N2L18 | Sliding to a halt | ||||
sensors | graphs | range | sampling | 30 Hz | |
MOTION | vel-time | -2 to +2 m/s | derivative | 7 pts | |
0 to 5 s | averaging | off |
N2L01 | Measuring position and velocity | ||||
sensors | graphs | range | sampling | 20 Hz | |
MOTION | pos-time | 0 to 4 m | derivative | 7 pts | |
vel-time | -2 to +2 m/s | averaging | off | ||
0 to 10 s | |||||
N2L02 | Position matching | ||||
sensors | graphs | range | sampling | 20 Hz | |
MOTION | pos-time | 0 to 3 m | derivative | 7 pts | |
0 to 10 s | averaging | off | |||
Match data: pieced line (1 m, 0 s)-(1 m, 1 s)-(2.5 m, 4 s)-(2.5 m, 6 s)-(1.75 m,7.5 s)-(1.75 m, 10 s) | |||||
N2L03 | Velocity matching | ||||
sensors | graphs | range | sampling | 20 Hz | |
MOTION | vel-time | -1.0 to +1.0 m/s | derivative | 7 pts | |
0 to 10 s | averaging | off | |||
Match data: pieced line (0 m/s,0 s) − (0 m/s,2 s) − (0.5 m/s,2.01 s) − (0.5 m/s,4 s) − (0 m/s,4.01 s) − (0 m/s,7 s) − (-0.5 m/s,7.01 s) − ( -0.5 m/s,9.99 s) − (0 m/s,10 s) | |||||
N2L04 | Fast and slow electric cars | ||||
sensors | graphs | range | sampling | 20 Hz | |
MOTION | pos-time | 0 to 4 m | derivative | 7 pts | |
vel-time | -2 to +2 m/s | averaging | off | ||
0 to 10 s | |||||
N2L05 | Measuring velocity and acceleration | ||||
sensors | graphs | range | sampling | 40 Hz | |
MOTION | vel-time | -2 to +2 m/s | derivative | 7 pts | |
acc-time | -4 to +4 m/s/s | averaging | off | ||
0 to 5 s | |||||
N2L06 | Position, velocity, acceleration of fan-driven cart | ||||
sensors | graphs | range | sampling | 40 Hz | |
MOTION | pos-time | 0 to 2.5 m | derivative | 7 pts | |
vel-time | -2 to +2 m/s | averaging | off | ||
acc-time | -1 to +1 m/s/s | ||||
0 to 5 s | |||||
N2L07 | Measuring forces | ||||
sensors | graphs | range | sampling | 40 Hz | |
FORCE | force-time | -10 to 10 N | derivative | 7 pts | |
0 to 30 s | averaging | off | |||
N2L08 | What connects motion and force? | ||||
sensors | graphs | range | sampling | 30 Hz | |
MOTION | vel-time | -2 to +2 m/s | derivative | 7 pts | |
FORCE | force-time | -8 to +8 N | averaging | off | |
acc-time | -10 to +10 m/s/s | ||||
0 to 5 s | |||||
N2L09 | Acceleration-force and velocity-force graphs | ||||
sensors | graphs | range | sampling | 40 Hz | |
MOTION | vel-force | -2 to +2 m/s | derivative | 7 pts | |
FORCE | acc-force | -8 to +8 m/s/s | averaging | off | |
-10 to +10 N | |||||
0 to 10 s | |||||
N2L10 | Motion with a constant force | ||||
sensors | graphs | range | sampling | 30 Hz | |
MOTION | vel-time | -1 to +4 m/s | derivative | 7 pts | |
FORCE | force-time | -0.6 to +0.6 N | averaging | off | |
acc-time | -0.5 to +2 m/s/s | ||||
0 to 5 s | |||||
N2L11 | Combinations of forces and masses | ||||
sensors | graphs | range | sampling | 30 Hz | |
MOTION | vel-time | 0 to 2 m/s | derivative | 7 pts | |
0 to 5 s | averaging | off | |||
N2L12 | Dueling fan units | ||||
sensors | graphs | range | sampling | 30 Hz | |
MOTION | vel-time | 0 to 2 m/s | derivative | 7 pts | |
0 to 5 s | averaging | off | |||
N2L13 | Elastic force | ||||
sensors | graphs | range | sampling | 40 Hz | |
FORCE | force-extension | 0 to 10 N | derivative | 7 pts | |
MOTION | -0.2 to +1 m | averaging | off | ||
position is defined as positive, variable called “extension” is defined as equal to -1 * “position” motion detector placed so cart moves toward it, extension and force zeroed at start of each run. | |||||
N2L15 | Air resistance | ||||
sensors | graphs | range | sampling | 40 Hz | |
MOTION | pos-time | 0 to +3 m | derivative | 7 pts | |
0 to 10 s | |||||
N2L17 | Frictional force | ||||
sensors | graphs | range | sampling | 40 Hz | |
FORCE | force-time | -1 to 10 N | derivative | 7 pts | |
0 to 30 s | averaging | off | |||
N2L18 | Sliding to a halt | ||||
sensors | graphs | range | sampling | 30 Hz | |
MOTION | vel-time | -2 to +2 m/s | derivative | 7 pts | |
0 to 5 s | averaging | off |
9. Selected Bibliography
The amount of information available on teaching Newton’s laws is enormous, consequently this section is selective rather than exhaustive.
Newton’s own work:
New translation of Newton’s Principia:
Textbooks:
Computer aided instruction:
PTRA teaching manuals:
Books and articles about physics teaching:
Books about Newton:
Books about standards and learning: