Graphing Your Motion

Transcription

1 Name Date Graphing Your Motion Palm 33 Graphs made using a Motion Detector can be used to study motion. In this experiment, you will use a Motion Detector to make graphs of your own motion. OBJECTIVES In this experiment, you will Use a Motion Detector to measure position, velocity, and acceleration. Use a computer to produce graphs of your motion. Analyze the graphs you produce. Match position vs. time and velocity vs. time graphs. MATERIALS LabPro interface Palm handheld Data Pro program Vernier Motion Detector masking tape meter stick walk back and forth in front of Motion Detector PROCEDURE Part A Position 1. Fasten a Vernier Motion Detector to a tabletop facing an aisle. Connect the Motion Detector to the DIG/SONIC 1 port of the LabPro interface. Connect the handheld to the LabPro using the interface cable. Firmly press in the cable ends. 2. Use short strips of masking tape on the floor to mark the 1 m, 2 m, 3 m, and 4 m positions from the Motion Detector. 3. Press the power button on the handheld to turn it on. To start Data Pro, tap the Data Pro icon on the Applications screen. Choose New from the Data Pro menu or tap to reset the program. Middle School Science with Vernier 2007 Vernier Software & Technology 33-1

2 Graphing Your Motion Palm Set up the handheld and interface for data collection. a. On the Main screen, a live distance reading should be displayed for the Motion Detector in DIG/SON 1 (in units of meters). a. Tap. b. Tap and choose Graph Matching. c. Tap to return to the Main screen. d. Tap on the Main screen to view a randomly generated target distance graph. You will return to this graph later in the procedure. For now, tap to view a blank distance vs. time graph. The vertical axis is scaled from 0 to 3 meters, and the time axis is scaled from 0 to 10 seconds. 5. Make a graph of your motion when you walk away from the detector with constant velocity. To do this, stand about 1 m from the Motion Detector and have your lab partner tap. Walk slowly away from the Motion Detector when you hear it begin to click. After data collection is complete, a graph of distance vs. time will be displayed. 6. Sketch what the graph will look like if you walk faster. Check your prediction with the Motion Detector. To take more data, tap again and then tap when you are ready to begin walking. 7. Sketch your results. 8. When you have completed Step 7, tap. 9. The Data Pro program will generate a random target distance graphs for you to match. 10. Write down how you would walk to reproduce the target graph. Sketch or print a copy of the graph. The vertical axis is scaled from 0 to 3 meters, and the time axis is scaled from 0 to 10 seconds. 11. To test your prediction, choose a starting position and stand at that point. Have your partner tap to begin data collection. When you hear the Motion Detector begin to click, walk in such a way that the graph of your motion matches the target graph on the handheld screen. 12. If you were not successful, tap to view a clean version of the same target graph. Have your partner tap to begin data collection when you are ready to begin walking. Repeat this process until your motion closely matches the graph on the screen. Print or sketch the graph with your best attempt. 13. Perform a second distance graph match (Steps 10-12) by tapping. This will generate a new target distance graph for you to match. PROCESSING THE DATA (Part A) 1. Describe the difference between the two lines on your graph made in Steps 5 and 6. Explain why the lines are different Middle School Science with Vernier

3 Name Date 2. How would the graph change if you walked toward the Motion Detector rather than away from it? Test your answer. 3. What did you have to do to match the graph you were given in Step 9? Part B Velocity 14. Tap the y-axis label and choose Velocity Match. Tap to view a blank velocity vs. time graph. The vertical axis is scaled from 2.0 m/s to 2.0 m/s, and the time axis is scaled from 0 to 10 seconds. 15. Make a graph of your motion when you walk away from the detector with constant velocity. To do this, stand about 1 m from the Motion Detector and have your lab partner tap. Walk slowly away from the Motion Detector when you hear it begin to click. After data collection is complete, a graph of velocity vs. time will be displayed. 16. Sketch your results. 17. Sketch what the graph will look like if you walk faster. Check your prediction with the Motion Detector. To take more data, tap again and then tap when you are ready to begin walking. 18. The Data Pro program can also generate random target velocity graphs for you to match. Tap. A new target graph will be displayed. The vertical axis is scaled from 2.0 to 2.0 m/s, and the time axis is scaled from 0 to 10 seconds. 19. Write down how you would walk to produce this target graph. Sketch or print a copy of the graph. 20. To test your prediction, choose a starting position and stand at that point. Have your partner tap to begin data collection. When you hear the Motion Detector begin to click, walk in such a way that the graph of your motion matches the target graph on the handheld screen. It will be more difficult to match the velocity graph than it was for the distance graph. 21. If you were not successful, tap to view a clean version of the same target graph. Have your partner tap to begin data collection when you are ready to start walking. Repeat this process until your motion closely matches the graph on the screen. Print or sketch the graph with your best attempt. Middle School Science with Vernier 33-3

4 Graphing Your Motion Palm 33 PROCESSING THE DATA (Part B) 4. Describe the difference between the two lines on the graph made in Steps 15 and 17. Explain why the lines are different. 5. What is the definition of velocity? 6. What did you have to do to match the graph you were given in Step 19? How well does your graph match the given graph? 7. Describe the motion needed to make this graph: If it is a position vs. time graph: If it is a velocity vs. time graph: You can check your answers using a Motion Detector. Part C Acceleration 22. Tap. Once the Main screen reappears a. Tap. b. Tap and choose Time Graph. c. Tap to return to the Main screen Middle School Science with Vernier

5 Name Date 23. Stand at the 1 m position, this time with your back to the Motion Detector. Have your partner tap. Pause for about one second and then walk rapidly to the 3 m mark and stop. Say stop when you have stopped. As you say stop, your partner should tap. 24. Tap on the y-axis label and choose ACC(m/s 2 ). Sketch the graph. PROCESSING THE DATA (Part C) 8. How does the acceleration vs. time graph differ from the other two graphs? 9. On your acceleration vs. time graph, label the acceleration and deceleration portions. 10. What is acceleration? Middle School Science with Vernier 33-5

6 Experiment TEACHER INFORMATION 33 Graphing Your Motion 1. The student pages with complete instructions for data collection using LabQuest App, Logger Pro (computers), EasyData or DataMate (calculators), and DataPro (Palm handhelds) can be found on the CD that accompanies this book. See Appendix A for more information. 2. There are three motion detectors that can be used for this activity. See for a comparison chart. 3. This experiment may be the first time your students use the Motion Detector. A little coaching on its use now will save time later in the year as the Motion Detector is used in other experiments. Here are some hints for effective use of the Motion Detector. In using the Motion Detector, it is important to realize that the ultra sound is emitted in a cone about 30 wide. Anything within the cone of ultrasound can cause a reflection and possibly an accidental measurement. A common problem in using Motion Detectors is getting unintentional reflections from a desk, chair, or computer in the room. Often unintended reflections can be minimized by tilting the Motion Detector slightly. If you begin with a velocity or acceleration graph and obtain a confusing display, switch back to a position graph to see if it makes sense. If not, the Motion Detector may not be properly targeting the target. The Motion Detector has a switch under the pivoting head. Set the switch to Normal mode. In Normal mode, the Motion Detector does not properly detect objects closer than 0.15 m. The maximum range is about 6 m, but stray objects in the wide detection cone can be problematic at this position. Sometimes a target may not supply a strong reflection of the ultrasound. For example, if the target is a person wearing a bulky sweater, the resulting graph may be inconsistent. If the velocity and acceleration graphs are noisy, try to increase the strength of the ultrasonic reflection from the target by increasing the target s area. 4. You may want to have your students hold a large book in front of them as they walk in front of the Motion Detector. This will produce better graphs because it smoothes out the motion. 5. The Part C graph is the only graph that should be printed in this experiment. Middle School Science with Vernier 33-1 T

7 Experiment 33 ANSWERS TO QUESTIONS Part A Position Answers have been removed from the online versions of Vernier curriculum material in order to prevent inappropriate student use. Graphs and data tables have also been obscured. Full answers and sample data are available in the print versions of these labs. Part B Velocity 33-2 T Middle School Science with Vernier

8 Teacher Information Graphing Your Motion Part C Acceleration (computer only) Middle School Science with Vernier 33-3 T