MOUSETRAP CAR PROJECT EWS Overview: You have just formed a racing team that will design and build the first mousetrap-powered race car. Your racing team will consist of 1-4 members. Engineering utilizes the steps of scientific inquiry to solve a problem by designing a solution. The problem you are being asked to solve is how to build a mousetrap-powered vehicle for maximum speed and distance. Just like any engineering / design team, you will work your way through the engineering cycle to help produce your vehicle. The cycle consists of 4 repeating phases: Design, Build, Test, Revise. You will continue the process until you come up with a design that meets the standards given below and bring you to engineering glory!! Objectives: ● to create a Mousetrap powered race car for maximum speed and distance ● to incorporate simple machines ● to learn how to calculate speed and acceleration Materials: ● 1 standard spring mousetrap (no rat traps) – any brand ● various materials to construct the racers depending on ● Grading Rubric (PDF) Rules: ● ● ● ● ● ● ● The mousetrap must power the car. You can build the car out of anything. It must have at least three wheels. Wheels are defined as anything that is round and goes around. The wheels cannot be wheels from a toy car. They must be made out of something that was not originally meant to be used as wheels. None of the wheels may leave the ground. THE CAR MAY NOT BE MADE FROM A KIT!! The car must be capable of traveling at least 3 meters. MORE POINTS for 10m of further!! ● Phase 1: Collect Background Information Define the following terms and give examples, then answer the questions that follow. You may use your textbook, the class PowerPoint, the mousetrap cars Slides, OR the Internet Term Definition Example Potential Energy Kinetic Energy Mechanical Advantage Work Power Lever Wheel and Axle 1. Watch the following video: https://www.youtube.com/watch?v=MqELXnBEEig Describe how you think potential and kinetic energy are demonstrated in a spring mousetrap. 2. A spring mousetrap is effectively a 3rd class lever. Look at the diagram below and use it to explain if a 3 rd class lever is a distance multiplier or a force multiplier. 3. How would energy use be different in a mousetrap car built for maximal distance compared to one built for maximal power/speed? 4. What are two types of friction that will affect the performance of your mousetrap car? Where specifically will these be encountered? Which would you want to minimize and which would you want to maximize? Part 1 Score Part 2: Design Considerations You are being asked to design a car that balances speed and distance. That means you will have to optimize your design for that purpose. When considering your design you must keep in mind the following features: 1) weight of the car, 2) placement of the mousetrap, 3) length of the snapper arm (also called pulling arm, lever or hammer depending on source), 4) size and type of wheels, 5) wheel to axle ratio. Use the pdf from Mesa to answer the following questions about each. 1. What do you think will happen if your car is too heavy? What if it is too light? 2. You may want to lengthen the snapper arm. How will lengthen the snapper arm affect the performance of your car considering long or short arms will release the same amount of energy but at different rates. 3. Where should the end of the snapper arm sit in comparison to the drive axle (the axle the snapper arm will pull on)? 4. How will you determine the length of string you will use? 5. Why would moving the mousetrap closer to the drive axle increase power / speed? Why would moving it further away increase distance? 6. Why would larger wheels be better for optimizing distance? What force do you want to increase on the wheels to help maximize power / speed? 7. Compare the optimal wheel to axle ratios for power versus distance cars. Part 2 Score Part 3: Design Your Car Materials – List all materials you plan to use Design Rationale – Address the following concepts in your design. How did you compensate for these forces and/or optimize your car to take advantage of them, include your blueprint on a separate sheet of paper. Sliding Friction (between axle and car body) Traction (rolling friction between wheel and floor) Power and Distance Weight (force of gravity on your car) BLUE PRINT: On graph paper, draw your design showing side, front, rear and top views. Include as much detail as possible giving estimated measurements etc. Part 3 Score Part 4: Build / Test / Revise - Analysis Build your car, test it and make any revisions keeping in mind you are trying to build a car that can travel up to 10m (~ 30 feet). Once you have a car you like. You will determine its average speed and acceleration. In the Table Below, calculate the mechanical advantage of the snapper arm (pulling lever) of your car: Table 1: Mechanical Advantage of Snapper Arm (pulling arm) Length (cm) Show work Answer Length of output arm (measure full length of snapper arm from spring (fulcrum) Length of input arm (measure length of spring arm from fulcrum – see diagram “applied force”) In the table below, calculate the mechanical advantage of your wheel and axle setup. If you have two different setups for front and back, just use the drive axle. Table 2: Mechanical Advantage of Wheel and Axle Radius (cm) Show work Radius of wheel Answer Radius of axle Speed and acceleration determination protocol: 1. mark out a 3 meter or 9 foot track on a smooth floor 2. divide the track into 1 meter lengths 3. time how long it takes for your car to travel 1 meter 4. repeat 3x and record the average 5. repeat steps 3 and 4 for distances of 2 and 3 meters. 6. Using the average time for each distance, calculate an average speed for each distance. 7. Record all data and calculations in Table 3 8. Make a scatter graph of average speed v. time (speed on the y-axis). Add a trend line and calculate the slope. ***If your car can go much further than 3 meters, use your cars max distance and divide into thirds instead of using 1, 2, and 3 meters) example: if your car can go 9 meters, use 3, 6, and 9 meters as your distances. Table 3: Speed and Acceleration Data Distance (m) Time (s) Average Time (s) Average Speed (m/s) 1 2 3 INSERT YOUR GRAPH IN THIS SPACE: Part 5: Discussion 1. What is the slope of your graph? 2. Describe how you calculated the slope of your graph. 3. What does the slope of your trend line reveal about your car? Remember, by calculating slope, you divided speed (velocity) by time. . . . . 4. What changes could you make to increase your vehicles acceleration? How do you think that would impact its maximum distance traveled? 5. What problems related to friction did you encounter and how did you solve them? FINAL GRADING RUBRIC: Part 1: BACKGROUND INFORMATION (5 points possible) All checkpoint work complete and on time Most Work completed and on time Minimal work completed or work turned in late 5 points 4 points 3 points Part 2: DESIGN CONSIDERATIONS (5 points possible) All checkpoint work complete and on time Most Work completed and on time Minimal work completed or work turned in late 5 points 4 points 3 points Part 3: CAR DESIGN PLAN: (10 points possible) List of parts needed/used to build vehicle. Drawings of vehicle (side view and top view). Sliding Friction section Rolling Friction section Power and Distance (modification of pulling arm) Weight section 2 points 4 points 1 points 1 points 1 points 1 points Parts 4 and 5: ANALYSIS AND DISCUSSION (20 points possible) Demonstrates excellent conceptual understanding of the physics principles behind a mousetrap car. Applies this understanding in conducting an excellent, meaningful investigation. Demonstrates good conceptual understanding of the physics principles behind a mousetrap car. Applies this understanding in conducting a good investigation. Demonstrates minimal understanding of physics principles behind a mousetrap car. Conducts a basic investigation. Demonstrates poor conceptual understanding of the physics principles behind a mousetrap car. Does not fully apply this understanding in conducting a meaningful investigation. 18-20 points 15-17 points 12-14 points 0-11 points MOUSE TRAP CAR CONSTRUCTION AND DESIGN: (20 points possible) Excellent application of design, construction and assembly. Very good construction and assembly and very good attention to detail. Good construction and assembly and some attention to detail. Fair construction and assembly. Minimum attention to detail. Last minute project. No attention to detail. Car is not homemade i.e. purchased kit was used: car is disqualified from race. Car travels 3m (5 points) +1 point up to 8m (max of 10) AWARD: COMMENTS 10 points 8 points 6 points 4 points 2 points 0 points 5+ +5
