PT2.3 - Construction of Car

Construction of the car

Prototype 1
Mass of mousetrap car210 g
Mass of each wheel97 g
Wheel diameter10 cm
Axel diameter2 mm
Length of string (from end of lever to axel)17 cm
Length of lever extension-
Overall length25.5 cm
Overall width14.4 cm
Overall height10 cm

Prototype 1 includes
  • CD wheels, coated with duct tape
  • A 3.125:1 gear ratio
  • Duct tape to act as string to pull gears, so as to increase friction and prevent the string from tangling






We quickly realise that the speed and distance achieved by Prototype 1 was not up to expectations. We made some edits to our car.

Thus resulting in our next prototype, Prototype 2.
Prototype 2
Mass of mousetrap car230 g
Mass of each wheel45 g
Wheel diameter8.5 cm
Axel diameter0.5 cm
Length of string (from end of lever to axel)29 cm
Length of lever extension15 cm
Overall length29 cm
Overall width15 cm
Overall height8.5 cm

Prototype 2 includes
  • A re-build of the entire car, using Lego parts
  • Changed gears to direct drive
  • Changed transmission of power to string instead of duct tape
  • Extended the lever



Prototype 2 uses a direct string drive and goes 5 meters in 5 seconds on flat tiled floor. We also extended the lever to ensure that the car can move a further distance. However, this is not fast enough to get the maximum marks for distance.

Prototype 3
Mass of mousetrap car250 g
Mass of each wheel45 g
Wheel diameter8.5 cm
Axel diameter0.5 cm
Length of string (from end of lever to axel)29 cm
Length of lever extension15 cm
Overall length29 cm
Overall width15 cm
Overall height8.5 cm

Prototype 3 includes
  • Changed gear ratio from to 2:1







The car now displays maximum mousetrap to wheel efficiency, achieving 10 meters in 5 seconds on regular tiled floor. This could be expected as we doubled the gear ratio, thus the speed also doubled. We requested for a newer mousetrap in hope that the higher tension in the spring of a newer mousetrap could result in higher speeds (which it did).

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