Physics Crash Barrier Lab To be completed in your lab notebook Pre Lab:  On a fresh piece of paper in your lab notebook write today’s date and the title of the lab.  Don’t forget to continue the page numbers in your lab notebook.  Don’t forget to add this lab and its page number to your Table of Contents. Purpose: To build a model of a crash barrier that will lower the force felt by a car. All crash barriers will be tested the same way by the teacher. The same cart will be rolled down an incline from the same height for all groups. Your crash barrier will be between the cart and a wall. The effectiveness of your bumper will be measured two ways: (1) Using an accelerometer on the cart we will determine the acceleration that the cart experienced when in contact with the crash barrier. With this information and the mass of the cart you will calculate the force that it felt. (2) Measuring the compression of your crash barrier. Materials: For Testing: Accelerometer probe Vernier software and interface Laptop

Incline plane (ramp) Wall or other immovable vertical surface Dynamics cart

Crash Barrier: You will have access to a set amount of 8.5”x11” paper to create your device. You may use only hot glue to connect your pieces. You are not allowed to use hot glue in excess for it is not a “structural material.” The glue should only be used at contact points between the paper and deductions will be made if it is used elsewhere. Design & Pre-Test Analysis: Draw your crash barrier in your lab notebook as much to scale as possible. Be sure to label all the pieces and clearly draw it so you will have a guide when you go to make it. Take as many measurements of your device as possible and record all of the information about it in your lab notebook. Different sketches may be helpful to clearly show different sides or the interior of your design. It is important to make all of these measurements before testing as your device will not be in the same condition after testing. You may draw the sketch on plain white paper and glue it into your lab notebook if you prefer. All groups will have access to the specifics of their test that were constant for all tests: the mass of the cart, the angle of the ramp, the initial height that the cart was released from, dimensions of the cart and distance that the cart traveled from the bottom of the ramp to the wall.

Post-test Measurements & Analysis: Print the graph provided by the computer of your test. Mark the portion of the graph when the cart was experiencing a force exerted by your crash barrier. Glue this graph into your lab notebook. For each measurement you made of your device before the test make those same measurements after the test. Record all of that information in your lab notebook. In your notebook, write a few sentences about which physical properties of your device changed after the test and why you think those particular values changed. Using the information you gathered (measurements, acceleration, etc.) determine the following for your specific crash test barrier: (1) The force experienced by the cart while in contact with your crash test barrier. (2) The time of contact between the cart and the crash test barrier. (3) The distance the cart traveled while this decelerating force occurred. Conclusion & Reflection: Questions: What was the overall effectiveness of your crash test barrier? Which aspects of your crash test barrier worked well and which did not? 1. Make one Claim that answer the questions above and can be supported using your test results and measurements. The Claim should answer the question, “What do you know?” 2. Cite Evidence that supports your claim based on the data you took during the lab. Your evidence should be specific but do not yet explain the next step. The Evidence should answer the question, “How do you know that?” 3. Now, explain your Reasoning, which means explain why the evidence you cited supports your claim (that answers the question). The Reasoning should answer the question, “Why does your Evidence support your Claim?” You may find this graphic organizer helpful for constructing your Claim, Evidence and Reasoning: Evidence #1 A fact you know from your lab; a piece of data but not an inference about that data.

Reasoning #1 Explains what your data tells you and how it supports your Claim in answering the question.

Evidence #2 A fact you know from your lab; a piece of data but not an inference about that data.

Reasoning #2 Explains what your data tells you and how it supports your Claim in answering the question.

Your Claim should answer the question but not include any information from your lab (data, etc.). It should be specific and clear.

Reflect on the following questions and record the answers in your lab notebook. Each should be answered completely and in age-appropriate sentences demonstrating what you have learned through this lab. Which aspects of your design would you change in future designs using the same materials and why? What do you think the effect of that change would be?