W=F d F=MA F 12 = -F 21 FACILITATOR - APPENDICES
APPENDIX A: CALCULATE IT (OPTIONAL ACTIVITY) Time required: 20 minutes If you have additional time or are interested in building quantitative skills, consider completing this additional activity. Step 1: Collect stopping distance data for different ramp heights. Measure the height of the car from the table in meters and record the value in the data table. Release the car and measure (in meters) the distance on the table from the bottom of the ramp to the place where the car stopped. Record this measurement and repeat for two additional ramp heights Stopping Distance (m) 1.05.094.69 2.07.135.82 3.10.190.98 4.13.250 1.12 5.15.285 1.20 6.18.348 1.31 2 4-H NATIONAL YOUTH SCIENCE DAY
Step 2: Collect speed data for different ramp heights. Using the same ramp heights, repeat the experiment to determine the car s speed using one of the following options: Option 1: App-ly Yourself! Download the Vernier Video Physics and the Vernier Graphical Analysis apps from the App Store. Participants can use the video and automated object tracking features to measure the velocity of the car. 3. Use the Origin and Scale tool to set the scale. Drag the Scale tool to each end of the car in the video. Set the scale to the length of the car, for example,.15 m. Video Recording Tips: Keep the camera centered on the experiment and do not move or pan the camera. Try to get as much light as you can on the subject. 1. In the Video Physics app, set up and record video of your car rolling down the ramp and crashing into the obstacle. Place your ruler or a meter stick so that it is beside the track and visible on the camera. 2. Move the tracking tool to the car and adjust its size to match the car. Tap Track. 4. Tap the Share button and select Data File. Then Open in the Graphical Analysis app. 5. Tap to select the highest point on the X velocity graph. Record the maximum velocity of the car in the table. 6. Repeat for two more ramp heights. APPENDIX 3
Option 2: Keep it Simple Use the camera on your phone to collect a video. Note: If this technology is not available, you can measure the car s time using the stopwatch. Consider measuring multiple trails and averaging the results to determine the time elapsed. This replaces substeps 2-5. To compute the average speed of the car, use the following steps: Average speed = distance traveled / time elapsed 1. Measure the length of the track. (This will be the distance traveled). 2. Record video of the car rolling down the ramp. 3. 4. 5. 6. Use the controls and the recorded video to find the frame where the car is released. Record the time, for example, 3.10 s. Find the frame where the car reaches the bottom of the ramp. Record the time. Subtract the first time value from the second. This is your time elapsed. Divide the distance traveled by the time elapsed. 7. Record the average speed in the table. 8. Repeat for the other two ramp heights examined in Step 1. 4 4-H NATIONAL YOUTH SCIENCE DAY
Step 3: Create a Stopping Distance vs. Speed graph. Using the graph below (or the Graphical Analysis app) graph your Stopping Distance and Speed data from your data table. Note that Stopping Distance values are plotted on the vertical y-axis and the Speed values are plotted on the horizontal x-axis. This yields a graph of the Stopping Distance vs. Speed. Step 4: Analyze the data and discuss trends. Examine your graph. Does the data fall in a straight line or a curved line? What conclusion can you draw about how the car s Stopping Distance is related to its Speed? Leader Notes Use your judgment to determine the appropriate level of analysis for your participants. Using one of the following approaches, help them observe that the data is not linear: What happens if you double the speed? Does the stopping distance double? What if you triple the speed? Does the stopping distance triple? If this is not the case, then the data is not linear. What happens if the car s speed is close to zero? Logically, we expect the stopping distance to be close to zero. Adding this additional point to the graph helps students see the data is not linear. If you are using the Graphical Analysis app, you will find that a Quadratic Curve Fit is a much better fit. Not only does it look like a better fit, but also the Root Mean Square Error (RMSE) value is smaller, which indicates a better the curve fit. Advanced participants may determine that stopping distance is proportional to the square of the velocity. As such, if you double the velocity, the stopping distance quadruples. If you triple the velocity, the stopping distance required to stop will be nine times the stopping distance of the original velocity. NINE TIMES! For teens that are learning drive, have them consider how far it takes them to stop when going 25 mph. If they re traveling at 50 mph, they will need four times that distance to stop. If traveling at 75 mph, they will need nine times that distance to stop! APPENDIX 5
APPENDIX B: TAKE IT FURTHER: MAKE IT SAFE The Engineering Design Challenge A safety engineer designs materials that allow cars and their passengers to stop more safely, usually by increasing the stopping time. An example is an airbag. An airbag s job is to quickly slow the passenger s speed to zero with little or no damage and before colliding into a steering wheel. Try this engineering design challenge! Think Like An Engineer The Engineering Design Process is a series of steps that engineers use to create a new product or process that solves a problem: 1. Identify criteria and constraints. 2. Brainstorm possible solutions. 3. Generate ideas. 4. Explore the possibilities. 5. Select an approach. 6. Build a model or prototype. 7. Refine the design. Challenge Using the heavy book as an obstacle, design an apparatus that stops the car safely without ejecting the passenger. Build and test your apparatus. Now revise your design. Test your design from different ramp heights and see whose design can go the fastest without losing the passenger. Did You Know? Statistics show that airbags reduce the risk of dying in a direct frontal crash by about 30%. 6 4-H NATIONAL YOUTH SCIENCE DAY
APPENDIX C: PULSE Time required: 15 minutes For younger participants, you may choose to replace We Need More Time! with this activity. Objective: Take your investigation further by exploring the human factors of motion. What is your reaction time? Materials A timer Step 1: Create a human circuit. Invite participants to form a circle either sitting or standing and hold hands. Ask everyone to close his or her eyes and concentrate. Explain that you will start a pulse by squeezing your right hand. Have a volunteer start a timer. As soon as your neighbor feels the squeeze in their left hand, they will squeeze their right hand to pass the pulse along. Continue in this manner until you receive the pulse in your left hand. Stop the timer. Step 2: Record your data. Divide the total time by the total number of participants in the circle. This yields the average reaction time, namely the average time it takes for a participant to recognize their left hand is being squeezed, and then squeeze their right hand. If time permits, you can repeat the activity three times and average the results. Step 5: Talk about it. Ask youth how the distracted reaction time compares to the undistracted reaction time. Do distractions increase or decrease your reaction time? What conclusions can you draw about how human factors, such as reaction time, affect your body s motion? How do you think talking or playing while trying to cross the street might affect your reaction time? The goal is for students to unite the concepts of motion and understand that both physical factors and human factors influence how our bodies move. In doing so, we can begin making connections to safety. Step 3: Think about it. Facilitate a discussion to help youth understand what their body is doing during the game. For example, when their left hand is squeezed, a message is sent to their brain notifying them that their hand is being squeezed. Their brain then sends a message to their right hand and initiates muscle movement in their right hand. All of these processes take time. The total time it takes our body to react and respond is called our reaction time. Step 4: Add a distraction. Repeat the same activity except this time, ask your participants to sing a song, such as Row, Row, Row Your Boat. This simulates a distraction. The resulting time recorded will be a distracted reaction time. APPENDIX 7
APPENDIX D: ADDITIONAL ACTIVITIES Extend your investigation beyond 4-H National Youth Science Day (NYSD) by performing any of the following supplemental activities. Each activity is designed to provide a better understanding of the relevance of motion in today s world. Capture and analyze everyday motion on a mobile device using the Vernier Video Physics app, available for purchase on the App Store. For more information, visit www.vernier.com/videophysics Additional Vernier activities include: Graphing Your Motion using a Vernier Motion Detector www.vernier.com/files/sample_labs/msv-33-comp-graphing_motion.pdf Crash Dummies using a Vernier Motion Detector www.vernier.com/files/sample_labs/msv-36-comp-crash_dummies.pdf Real-World Accelerations using a Vernier Accelerometer www.vernier.com/files/sample_labs/pwv-21-labq-accelerations_real_world.pdf About Vernier Software & Technology Vernier Software & Technology has been a leading innovator of scientific data-collection technology for 34 years. Focused on science, technology, engineering, and mathematics (STEM), Vernier is dedicated to developing creative ways to teach and learn using hands-on science. For more information, visit http://www.vernier.com Oregon State University 4-H Youth Development Programs Additional STEM experiments are available free, online from Oregon 4-H at http://oregon.4h.oregonstate.edu/science-engineering-and-technology 8 4-H NATIONAL YOUTH SCIENCE DAY