energy conservation in mousetrap cars

12.07.09. A variety of systems can be understood fruitfully and quantitatively through the language of energy conservation, including a living cell, a falling book, or, as with Mr. Seymour and Mr. Wasylyk's Integrated Project Design (IPD) this week, a model car. In teams students constructed cars out of paint stirrers (chassis), CDs (wheels), and mousetraps (the power source), focusing on design concerns such as weight minimization, the tradeoff between distance and speed, and the dual role of friction as both helpful (wheel grip) and harmful (axle rubbing). Energy conservation proved a useful lens as we discovered with students how the initial potential energy stored in the mousetrap spring is converted into the translational kinetic energy of the car, the rotational kinetic energy of the wheels, and the eventually dominant heat energy lost due to axle friction. A visual demonstration of this energy transfer was presented and is included here as a video.