5. Discussion and Conclusion

5.1 Key findings

We found that a lightweight body was crucial to allowing the car to travel further, as there is lesser load. This was accomplished by a “skeletal” approach to building our car, where as little components were used as possible to reduce weight. This was proven by early trials which demonstrated the car’s potential to travel a decent distance.

However, while the design of the car had been successful, its implementation into a physical, real-life model has not worked the way we expected it to be. Even if the design was proven to work and the car managed to travel 7 metres, the structural load upon the car was too much for the body to handle. After the third run of the post-modification trial, the car had simply disintegrated. We can conclude that the build of the car was not solid enough to allow the car to function properly.

5.2 Comparisons with other designs based on research

The key feature of our design was its light weight. This may have allowed it to be more successful than other cars which used heavier materials such as wood and gears, if the structural build was not compromised.

However, after comparing with other designs, we feel that maintaining the structural integrity of the car with stronger (and heavier) materials in exchange for weight increase is a much better compromise, as having the car fall apart is more disastrous than having it move slowly.

5.3 Evaluation of engineering goals
In all, most of the engineering goals were accomplished:

a) Uses only the MouseTrap provided as the only energy source
Yes, the car does not utilise any other sources of energy.

(b) Has a maximum length of 30 cm, width of 10 cm, and a height of 10 cm
No, as the length exceeded by 6 centimetres (if including lever). However, the width and height stayed well within limits.

(c) Can travel a minimum distance of 5 meters carrying an egg
Yes. The maximum distance our car could travel was 7 metres. At worst, its performance was only 2 metres short, at 5 metres.

5.4 Areas for Improvement

The axle diameter is an important factor that controls the power output. Smaller drive axles produce less torque and decrease the power output. We can get more turns of string around a smaller drive axle and thus will have more turns of the drive wheel translating into a greater pulling distance. The diameter of the rear wheel axles should be reduced to increase the power output of the mousetrap car.
Secondly, we are currently using a circular axle, rather than preferred hexagonal one. A hexagonal design allows the cotton twine to wrap around tighter, which is more efficient.
The stability of the car’s superstructure is important as it ensures that the car can handle the tension of the mousetrap and other external forces. As we learned the hard way, having a stronger superstructure can prevent the car from disintegrating due to the tension.

5.5 Practical Applications
These individual parts of a mousetrap car can be seen as analogous to the real-life manufacturing of cars. Car designers need a chassis that looks aesthetic while being lightweight and structurally solid. Car engineers want the car to move fast and reduce friction. Through this physics performance task, we can explore through the simplest activity the blood and sweat that goes into designing and making a car, and allows us to appreciate such modern marvels.

At the same time, we were also given the opportunity to use physics formulas and concepts outside of worksheets, and solve problems that expands on our thinking.

5.6 Areas for further study
In the modern world the main problem that we face is the depleting amount of non-renewable energy resources. Fuel consumption by vehicles accounts for a large percentage of use of petroleum or diesel. Even as greener hybrid, natural gas-fuelled and full electric cars are produced, they had not gained traction in the car market. Because internal-combustion-engine cars are unlikely to be fully replaced in the near future, it would be a major breakthrough if one is to develop a kinetic energy retainment system for ordinary combustion engine cars so as to reduce oil consumption. This system may be designed from a few concepts taken from the mouse-trap mechanism.

5.7 Bibliography

[1] Carter, C., et al. (2014). How to Build a Mousetrap Car. Retrieved February 24, 2014, from: http://www.wikihow.com/Build-a-Mousetrap-Car

[2] S. Holmes, G. (n.d.). Mousetrap. How Products Are Made: Volume 5. Retrieved March 25, 2014, from: http://www.madehow.com/Volume-5/Mousetrap.html

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