Mousetrap car design and performance report

Engineering Design Project -- Mousetrap Car

This project involves the development of a self-propelled vehicle from a standard mousetrap. To meet that objective, the experimenter must convert a tool designed for a specific use unrelated to locomotion (i.e. trapping mice) into a self-propelled vehicle capable of traveling 10 meters without external propulsion assistance. That process requires a practical design phase and the conceptual consideration of several conceivable approaches to the task. The selected design will be constructed and tested to determine whether the project objective has been achievable.

In general, the design process consists of conceptualizing the expected viability of all of the identifiable ways to achieve the objective. After identifying the design engineering task, the experimenter must eliminate those approaches that are valid in principle but impractical to achieve with the materials provided. Then, the remaining approaches will be considered in terms of relative likelihood of success, cost, and ease of implementation. Usually, that process will also include drawings and the construction and testing of scale prototypes to estimate effectiveness, but the most important phase is testing of the completed design.

Identifying the Engineering Task

In this case, the engineering task consists of two principal issues: (1) eliminating as much resistance (mainly friction) to efficient propulsion as possible, and (2) applying the mechanical energy potential of the mousetrap frame to produce mechanical energy that propels the device forward.

Conceptualizing and Evaluating Different Engineering Solutions

The two methods of generating mechanical propulsion were: (1) altering the trapping bar to exert backwards force against the surface of the floor to produce forward momentum, and (2) altering the trapping bar to propel a weight backwards to generate forward momentum through Newton's Second Law of Motion. In either configuration, two sets of wheels would be mounted on rotating axles. During the conceptualization phase, it was determined that the first approach was impractical because the amount of force generated by the trap would be too great to convert the rotational force of the bar into a lateral force in the backward direction. The second approach was accepted.

Manufacturing, Assembly, and Implementation of Selected Design

During preliminary testing, it was determined that the main engineering problems would be: (1) limiting the force of the mechanism, and (2) determining the best way to attach an appropriate weight so that the release point would allow energy to be converted into forward propulsion as efficiently as possible. In that regard, string with attached metal hooks was used to hold back the trapping bar at the halfway position and a slipknot was used to permit the activation and release of the bar. A small piece of tin was added to the middle of the horizontal segment of the trapping bar and positioned at an appropriate angle to launch a small weight backwards.

Testing, Evaluation, and Conclusion