For this project, we made a car using an alternative energy source. For example, some of the people in our class used the sun (solar energy) or air as their energy source. We used rubber bands. Our car works by wrapping the rubber band around the axle eight to twelve times, and then letting the car go. While making the car, we first planned what we wanted the car to look like and how it would work. Then, we started to build our car. Most of the time we had during this project we used for testing and modifying our car. Since it was so small, it was hard to make it go the full five meters we needed it to go. In the end, we did get our car to go five meters most of the time.
Concepts
Potential Energy (spring) - the energy stored in a spring (PEe=1/2kx^2). We found the potential energy of our rubber band. Kinetic Energy - energy due to motion (KE=1/2mv^2). We found the kinetic energy of our car at each meter. Spring Constant (k) - the measure of how much a spring wants to pull back together (F=kd). We found the spring constant using the mass, acceleration, and distance of the car. Thermal Energy - the internal energy of an object due to its kinetic energy (Total Energy - (KE+PE) =Thermal Energy). We found the thermal energy after we found the kinetic, potential, and total energies. Distance vs. Time - shows how an objects distance changes with time. We made a graph showing this in our presentation. Acceleration vs. Time - shows how an objects acceleration changes with time. We made a graph showing this in our presentation. Velocity vs; Time - shows how an objects velocity changes with time. We made a graph showing this in our presentation.
Reflection
This project was different from my first two projects. Instead of taking a while to plan out what we were going to do and actually figure out how to accomplish what we had to, we were quick to start building our car. This was great for our group because it boosted our self esteem because things were actually working. It make us work faster. However, because we didn't plan out our car too well, it didn't work too well when we were done building it. This was a major setback because we had to almost completely rebuild our car. After that, we rebuilt and tweaked our car many, many times and we were almost set on it not working. We had started with a small piece of wood as our base which made it more difficult for our car to go five meters. Then, after lots of hard work and different rubber bands, our car worked! We were prepared to spend another day hopelessly trying to make it work, but the screw in our car had fallen too far through and was useless. We drilled a new hole in a slightly different place, and tried our car again, and it worked! The only thing we needed to change was the screw that held the rubber band in place. After testing our car multiple times in disbelief, we began to work on our calculations. This was a whole new experience for me. It turns out elastic energy is a little more confusing to me than I thought. We had to redo our calculations three times to get the correct data, but it worked out okay in the end. Unfortunately, during the presentation, the rubber band got stuck and our car didn't work. After rewinding, we tried again and were successful. This project was a lot of fun and I learned a lot of things. For example, bossing everyone in my group around may not be the best way to work with them. I also learned that planning and preparing are just as important as building and testing. In conclusion, I think this project was a fun way to learn about elastic energy and how to build an alternative energy car.