This in-depth physics / science / technology activity can be modified to require 2 to 5 hours, depending on the number of redesign steps students are permitted, and the number of educational standards you want to address. 4 In addition, the following non-expendable items are required (and can be used many times): A basic wooden ramp with a variable angle and cars for each group.

Student groups are provided with a generic car base for which design a device/enclosure to protect an egg on or in the car as it rolls down a ramp at increasing slopes. Students are expected to perform basic mathematical calculations using their data.

Automotive manufacturers hire engineers to redesign cars in an effort to make them safer. This process always involves a trade-off between cost of manufacturing a new design and level of safety. After this activity, students will be able to recognize this trade-off and understand the concept of cost to benefit ratio. engineering design process inertia center of gravity material properties mass weight speed acceleration friction Newton's laws gravity angles slopes ratio cost to benefit ratio Ratios, proportions, Newton's laws, linear motion calculations, data collection and graphing. explain the engineering design process. explain the relationship between distance, time and speed. describe how one can use math to solve a problem. wooden ramp with adjustable incline (6 ft long, 7-8 inch wide track, elevation 0º to 90º) (one per class - see attachment for details on how to build one) 5" x 8" wooden base (1 per group) screw eyes (4 per group) threaded rod to fit through screw eyes or wooden dowel (2 per group) wheels (hobby or cut from a dowel) (4 per group) e-clips or washers (4 per goup) stop watches meter stick protractor balance string stapler scissors razor blade eggs (at least one per group) (optional) wooden eggs for practice Assortment of construction materials and supplies, such as: cardboard squares, pipe cleaners, small and large rubber bands, cotton balls, soda straws, craft sticks, masking and scotch tape, soda bottles, super glue, packaging peanuts, paper and plastic cups, bubble wrap, binder clips, staples You and your team are members in the research and development department of a major car manufacturing company. You are in charge of testing a prototype safety harness on the latest line of cars. Your research team has provided you with instructions to create the device. Now it's your job to construct and test this prototype and determine how effective it is. In a real lab situation, the car would be accelerated into a wall. As you do not have the facilities to perform this test, you will use a ramp to simulate acceleration. To do your test, run your prototype car down the ramp starting at the lowest angle and see how well it performs. If it passes one angle, increase the slope and run the experiment again. If it fails, record the angle and stop testing. Compare your results with those of the other tests in the class to determine the average angle at which the prototype's safety mechanism failed. Based upon your results, make a recommendation as to whether or not the safety mechanism is effective. The company standards require that the safety mechanism be able to withstand an impact at a 50º incline run. Introduce the challenge: To design a safety device that can hold an egg on the model car and keep it from breaking as the car is rolled down the ramp at increasing slopes. The target is to have the egg roll down the ramp at a 50 degree angle without cracking. Give extra credit to groups that can acheive success at greater angles. Ensure that while the students are making the total cost calculations, they include only the cost of the materials used in the final devices. They may have redesigned their devices while constructing and decided not to use some of the materials they chose initially. They should not be charged for materials that they did not end up using in their final product. Explain the constraints (see attachment). Conduct the activity. After completion of the activity, discuss the importance of having the "cost-to-performance" ratio and review the physics principles that can be observed in each device prototype. (see the attached Notes By a Teacher for details) Distribute student handouts (see attachments). Work in groups to discuss and draw possible solutions and choose the best ideas. (Make a brainstorming/sketch graded component of the project). This is a possible breakpoint for a short activity. The teacher verifies that the group has a unified drawing or idea, and the group is allowed to "purchase" materials. Groups are given 30-60 minutes to construct their devices. Calculate materials cost. This is another possible breakpoint. One group presents its design, describing the construction, explaining why it is designed as it is, and announcing the construction cost to the class. The teacher records the construction cost in the design database (which could be a chart on the wall or a spreadsheet projected for the class to see). S/he then revisits the design constraints and verifies that the device is in conformance. Have each group take the mass of its device (record in data table). The device is then tested at a low slope on the ramp. Record the time it takes to move down the ramp and the incline number of the ramp in the data table. The device is repeatedly tested until the highest slope is reached or the egg is broken (to any observable degree). If a device needs minor repairs between runs, the design team can be given a set amount of time (perhaps 1-2 minutes) to make the minor repairs (record mass of newly designed device). Each device is checked and tested in the same manner. (optional) Determine angle measurements for each incline number. Calculate weight, speed and cost/performance ratio*. Use the attached Excel file to project the results on a screen/wall. * Note: The fictional dollar cost from the "Cost Account" sheet is divided by the highest ramp level survived to create the cost/performance ratio. Design Constraints Handout (doc) Design Constraints Handout (pdf) Cost of Materials and Data Table Handout (doc) Cost of Materials and Data Table Handout (pdf) Notes By a Teacher (doc) Notes By a Teacher (pdf) Performance vs. Cost Projection Sheet/Handout (xls) Performance vs. Cost Projection Sheet/Handout (pdf) Ramp Construction Method (pdf) Picture of Car Assembly Parts (jpg) Sample Rubric (pdf) Sample Rubric (xls) Team Member Peer Evaluation Form (doc) Team Member Peer Evaluation Form (pdf) Controlled use of incline ramp (pinched fingers, watch your toes, etc.). Wooden eggs could be provided for designing purposes. An option for teachers who have enough material is to not charge for materials used in designs that were not tested. You want the students to experiment. The cost should be the finished cost (manufacture cost) not the development cost. It should be the cost of the materials needed to make the car they dropped. See the attached sample rubric. If cooperation and doing one's fair share of the work are issues, consider giving the group a fictional dollar amount bonus to divide amongst the group members at the end of the project as they deem fair, or use a peer evaluation sheet (see attachment). If time and enthusiasm permit, have students re-design their solutions at home for presentation to the class at a later date. Have students evaluate their own devices: What is good/bad about the design solution and why? How could it be improved? Explore what formula might provide a fairer cost/performance ratio. Explore how to mass-produce the best design(s). All of the standards related to manufacturing could be addressed through the production process. Use weight of the device constructed as a design constraint. Refer to the attached Notes By a Teacher document, created by Joshua Abrams of Meridian Academy, which explores possible activity extensions, scaling and concepts addressed by the activity from the physics and math perspective. Depending on the level of the class, make use of the "possible breakpoints" indication in the procedure. If availability of materials is an issue, stop at the point at which students draw device sketches. Have them explain their designs and discuss how they might be successful or not. Another possibility is to have students bring in their own materials for the cars, although this makes the car bases uneven across the class, but the physics principles can still be observed in the devices they build.