During this project, my group — the same group I was in during the ¨Fire Away!¨ project — had to design — and build — a vehicle that could safely transport two 125g passengers (250g total) as close to 5m as possible. We were not allowed to alter the ground, or use chemical or nuclear energy. My group decided to use spring energy (or elastic energy). We built a car with thick, small front wheels and thin, large back wheels. This design helped the car travel smoothly, while still utilizing rotational inertia). The power source is essentially a sling shot that is pulled back 0.12m. The body of the car is a large, heavy piece of redwood and the axles are wooden dowels that rotate in a combination of metal and PVC pipe. On the back, we attached a long piece of wood that could easily be pulled back against the slingshot — without damaging the back wheels. The passengers are secured in PVC pipes on top of the car. We continued to slightly alter our car as we began to test it; a few examples would be making the back wheels larger and thinner, attaching a long piece of wood to the back of the car so it could easily be launched with the slingshot and moving the passengers closer to the front of the top of the car — to help reduce drag.

Spring Potential Energy: potential energy stored in the structure of an object that occurs when [temporary] elastic deformation is applied to it through work; e.g. compress, stretch, etc. In this case, the spring potential energy of our slingshot was stored in the stretch of our rubber bands. The equation is PE = ½*k*x² where k is the spring constant and x is the distance the rubber bands are stretched — about 0.12m. The spring potential energy of our slingshot was 3.95J.

Kinetic Energy: the energy an object has in motion. We calculated this for our car to see how much of our potential energy was not lost to heat. The equation is KE = ½*m*v². The result was 2.98J at 1m, 2.27J at 2m, 1.79J at 3m, 0.85J at 4m, 0.27J at 5m, and 0J at 5.1m.

Total Energy: the total amount of energy the vehicle has during its run. The equation is TotalE = PE + KE + TE. The result was 3.95J.

Thermal Energy: the amount of potential energy lost to heat. The equation is TE = TotalE - PE - KE, or, in our case, TE = PE - KE. We calculated this to help determine the efficiency of our vehicle. The result was 0.97J at 1m, 1.68J at 2m, 2.16J at 3m, 3.1J at 4m, 3.68J at 5m, and 3.95J at 5.1m.

Velocity: the speed a moving body has in a specific direction. We used this to find the acceleration of our car throughout its run. The equation is V = Δd/Δt. The result was 2.44m/s at 1m, 2.13m/s at 2m, 1.89m/s at 3m, 1.3m/s at 4m, 0.74m/s at 5m, and 0.25m/s at 5.1m.

Acceleration: the rate of change of an object´s velocity in a certain amount of time. We used this to see how kinetic and thermal energy changed [proportionally] throughout the car´s run. The equation is a = Δv/Δt. The result was 5.95m/s² from 0m to 1m, -0.66m/s² from 1m to 2m, -0.45m/s² from 2m to 3m, -0.77m/s² from 3m to 4m, -0.41m/s² from 4m to 5m, and -1.23m/s² from 5m to 5.1m.

Rotational inertia: a scalar value that determines the difficulty to alter the rotational velocity of an object around its axis of rotation. We used this to determine the difference between the inertia of the front and back wheels of our car. The equation is Rotational Inertia = m*r², where r is the radius of the rotating object. The result was a rotational inertia of about 0.94kg m² for the front wheels, and 0.54kg m² for the back wheels.

During this project, I feel like I did a good job utilizing citizenship, as well as thinking critically. I thought critically when I helped my group think of ways to get values for our calculations (e.g. time, distance, etc.). I also thought critically when our car began to turn right during every run, and helped my group replace the axles — which had broken, and reattach the wheels to the new axles. I utilized citizenship when I helped my group calculate other values, as well as when I helped work on — and revise — the presentation, and when we were actually building our car; I listened and communicated respectfully with my group and tried my best to think ethically while working.

In the future, I can improve on my creativity and collaboration. I can think more outside-the-box — so to speak — and come up with fresh ideas to make my group´s project function in ways different than my other classmates; for instance, during this project, every group in my STEM periods used spring energy to power their cars, and I feel like I could have done a more original idea — like a ramp. I can improve my collaborating by dividing up work better; some group members met to work on our project after school, but they did not contact me. I could have reached out and done a better job communicating outside of class as well. That way, hopefully, my future group members won´t feel like they have to work on our project alone after school.