TECHNOLOGY-BASED LAB ACTIVITIES

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DEVELOPING THE MODEL Large rates of acceleration experienced by the human body are often measured in units of the free-fall acceleration g. The body of a healthy person can safely withstand accelerations of about five times the free-fall acceleration, or 5g, for periods of a few seconds. As a guideline, you have been given a graph of acceleration versus time for a real bungee jumper using a standard bungee cord (below). In real bungee jumping, the bungee cord should stretch from 2.5 to 4 times its original length before stopping. In addition, the bungee cord should be matched to the weight of the jumper so that it still has a significant ability to stretch when the jumper reaches the bottom of the ride. The jumper should also experience at least two bounces with little or no tension in the bungee cord. Your laboratory model should approximate these specifications. 40 Data from an Actual Bungee Jump 30 Acceleration (m/s 2 ) 20 10 0 –10 Free fall –20 0 5 10 15 20 Time (s) When setting up your model, start by checking the following characteristics of the bungee cord you will be using. Write answers to the questions before going on to the Procedure section. 1. Determine the cord’s ability to stretch. You can do this by measuring the length of a small section, then stretching it and measuring the stretched length. Describe in writing the ability of your cord to stretch. 2. You will use a plastic bottle filled with gravel to model the jumper. Securely attach the cord with a solid knot through an eyebolt in the lid or around the neck of the bottle. Ask for help if necessary. Hold the end of the cord in one hand and the bottle in the other hand. Make sure the bottle will not hit your feet or any other students, then drop the bottle. Use the meterstick to determine if the bottle causes the cord to stretch to at least two times its original length. Make sure that the cord does not stretch to its maximum length and that the bottle does not hit the ground. Add gravel to or remove gravel from the bottle to adjust the model, always making sure you securely tighten the lid. Comment on the range of displacement experienced by the jumper. 3. When you dropped the jumper, did the jumper experience two bounces in which the cord lost all or nearly all of the tension? Explain how you could tell when this happened. Copyright © by Holt, Rinehart and Winston. All rights reserved. 8 HOLT PHYSICS Technology-Based Lab Activities
PROCEDURE Copyright © by Holt, Rinehart and Winston. All rights reserved. 1. Connect the accelerometer to CH 1 of the CBL unit. Use the black link cable to connect the CBL unit to the calculator. Firmly press in the cable ends. Use tape to securely attach the accelerometer to the plastic bottle. The arrow on the accelerometer should point upward. 2. Securely attach the cord to the neck of the bottle or to an eyebolt in the lid of the bottle. Securely attach the other end of the cord to a rod that is clamped to the edge of the lab table. Adjust the length of the cord so that the bottle does not hit the floor when dropped. Ask your teacher for help if necessary. Measure and record the unstretched length of the cord. 3. Turn on the CBL unit and the calculator. Start the PHYSICS application and proceed to the MAIN MENU. 4. Set up the calculator and CBL for the accelerometer. • Select SET UP PROBES from the MAIN MENU. • Select ONE as the number of probes. • Select ACCELEROMETER from the SELECT PROBE menu. • Confirm that the accelerometer is connected to CHANNEL 1, and press e. • Select USE STORED from the CALIBRATION menu. • Select LOW-G from the ACCELEROMETER menu. 5. The accelerometer must be calibrated so that it records for the vertical direction only. The accelerometer should record zero acceleration when at rest and −9.8 m/s 2 during free fall. You will verify this later in steps 8–9. • Rest the bottle on the table, so that the accelerometer arrow points directly upward. • Select ZERO PROBES from the MAIN MENU. • Select CHANNEL 1 from the SELECT CHANNEL menu. • When the reading on the screen is stable, follow the instructions on the calculator to zero the sensor. 6. Set up the calculator and CBL for data collection. • Select COLLECT DATA from the MAIN MENU. • Select TIME GRAPH from the DATA COLLECTION menu. • Enter “0.05” as the time between samples in seconds. • Enter “80” as the number of samples. • Press e, and select USE TIME SETUP to continue. To change the sample time or sample number, select MODIFY SETUP instead. 7. Hold the bottle at the height of the rod. Make sure the arrow on the accelerometer points up. Press e to begin collecting data. Hold the bottle motionless for one second, then release it. Catch the bottle before it reaches the bottom of its fall, while the cord is still slack. 8. When data collection has finished, press e to see your graph. Trace across the graph with the cursor keys. For the first second or so, the acceleration should be near zero. This value represents the acceleration of the bottle before it began to fall. CHAPTER 2A 9
Page 1 and 2: TECHNOLOGY-BASED LAB ACTIVITIES CBL
Page 3 and 4: Contents Introduction to the Techno
Page 5 and 6: HOLT PHYSICS Introduction to the Te
Page 7 and 8: HOLT PHYSICS Downloading Graphing C
Page 9 and 10: HOLT PHYSICS Safety in the Physics
Page 11 and 12: Chapter 1 HOLT PHYSICS Technology L
Page 13 and 14: • Press e, then select USE TIME S
Page 15 and 16: 21. Remove the masking tape strips
Page 17: Chapter 2 HOLT PHYSICS Technology L
Page 21 and 22: ANALYSIS 1. Graph tracing Use the c
Page 25 and 26: Copyright © by Holt, Rinehart and
Page 27 and 28: the rates of free-fall acceleration
Page 33 and 34: 5. Applying theory The equation in
Page 39 and 40: Shoe: _______________ Mass of shoe:
Page 45 and 46: CONCLUSIONS 6. Applying the model A
Page 47 and 48: DEVELOPING THE MODEL You have decid
Page 49 and 50: ANALYSIS Copyright © by Holt, Rine
Page 51 and 52: 10. Applying results According to y
Page 53 and 54: DEVELOPING THE MODEL You will use a
Page 55 and 56: • Press e and select CHANNEL 1 fr
Page 57 and 58: 6. Calculating The change in moment
Page 59 and 60: DEVELOPING THE MODEL In this activi
Page 63 and 64: • Press e, and read the mean acce
Page 65 and 66: 2. Making predictions You can also
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DATA TABLES Fabric type Wet or dry?
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Chapter 12 HOLT PHYSICS Technology
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5. Observe the reading on the calcu
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8. Thinking critically In designing
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DEVELOPING THE MODEL The microphone
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• Select ADJUST A from the MODEL
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Copyright © by Holt, Rinehart and
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DATA TABLE Artificial light and two
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6. Comparing results Compare the av
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DEVELOPING THE MODEL Figure 19-1 sh
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6. Drawing conclusions What is the
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DEVELOPING THE MODEL The ability to
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Part II Parallel Circuits 14. Conne
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3. Calculating Using your measureme
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DEVELOPING THE MODEL First, you wil
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• Press e to see a graph of your
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