Engineering Goals and Brainstorming(PT 2)

Design Criterion
After much discussion, we have decided on the criterion to follow to determine the best design for our mouse trap car.

We aim to construct our car with respect to the following factors.
  • Weight of Car 
According to the Newton's Second Law, Force = Mass * Acceleration. As the value of the Mass decreases, the value of Mass * Acceleration decreases, thus the magnitude of the force required decreases. This increases the efficiency of the car.
  • Shape of the Car
As the velocity of the car increases, the air resistance acting on the car increases. Having a aerodynamic shape for the car will decrease the air resistance acting on the car.  As air resistance decreases, the net force acting on the car increases, as the acceleration is constant.
  • Materials 
As different materials have different molecular structure, the properties of each material is different. Therefore the material used must be carefully selected based on hardness, strength and flexibility to ensure that the car does not bend or break apart easily.

  • Wheels
The wheels will be the part of the car in contact with the ground, transferring the energy from the spring to rotate the wheels, thus the wheels must have enough surface area to do so. However, the wheels should not be too thick as it would cause the motion of the car to be less supple.

Our goals for the car include:

1. The weight other materials, excluding the mouse trap, to be less than 200g.

This is because the mouse trap is made of metal, therefore it's weight is substantial just by itself. Since the smaller the weight, the smaller the force will be required, keeping the weight of the entire car at it's bare minimal is crucial in achieving a high efficiency for our car.

2. The total displacement of the car to be 7.5m.

This is because according to the scoring system, the maximum displacement is 7.5m. The car having a total displacement of 7.5m will ensure a higher score.

3. Shape of the car to be aerodynamic.

This is because the test will be conducted in a carpark where breezes can often be felt as it is an open area. Wind causes air resistance if the car is moving against it. In order to decrease air resistance by the wind, the shape or the car must be aerodynamic. An aerodynamic car will also increase the speed of the car.

3 Unique Car Designs

*Due to the rat trap being very big and bulky, most people have used normal mousetraps. However, these designs should work the same with a rat trap as a mousetrap.

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