PT2.4 - Testing of car

Final Design:

Updated dimensions of mousetrap car (post-modifications)

Mass of mousetrap car
Mass of each wheel
Wheel diameter
Axle diameter
Length of string
Length of lever extension
Overall length
Overall width
Overall height

Photo of final design:

Video of final design:


From 1 to 3 seconds, the car was accelerating. After that from 3 to 5s, the car was moving at a constant speed and finally from 5s to 6s, the car slowed down in speed before it came to a complete stop.

Final assessment data table:

Run number(max. 3 trials)
Trial 1
Trial 2
Total time of Run / s
Total distance of Run / m
Total Score

Post-testing Discussion:

1. Using the data table, calculate the average velocity for your mousetrap car during    the best run in the final assessment.

7.5m/6s = 1.25m/s
7.5m/6.2s =75/62 m/s = 1.21m/s(2 d.p.)
Average velocity= 1.23m/s(2 d.p.)

2.Which part of your mousetrap car design worked best? Explain your answer

      The mechanism at the axle worked the best as compared to the other countless mechanisms we had added to the car, it made the most significant change in both the speed the car travelled and the overall distance travelled by the car. This was due to the fact that before we made the improvement, we had hot glued one end of the string to the axle. This caused the car to immediately stop the moment the string had fully unwound from the axle. However, we managed to make a mechanism such that once the string unwound, the string would just detach from the axle causing the car to travel further with the momentum that it already possessed. 

3. If you had more time to work on your mousetrap car, state and explain how you will improve/modify the current design?

   We would have added gears to further maximise the original efficiency that our car had after the final improvement. This was originally supposed to be added to the car. However, due to the fact that there was a delay in the process. The gears added will increase the number of the times the axis turns. The bigger gear (on a separate axis) turning once would result in the smaller gear (attached to the wheel axis) spinning multiple times as the large gear on the right will turn more slowly than the smaller gear on the right.  The large gear also can handle more torque (rotational force) than the small gear does. Therefore, causing the car to go further and faster.

Explained by GIF below

 Ryan, V. (n.d.). Working out Revolutions Per Minute [Digital image]. Retrieved April 3, 2016, from 

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