Each car that was built moved by elastic potential energy turning into kinetic energy. Elastic potential energy is potential energy stored by the stretching or pulling of a spring, and in this case the spring being the rubber band. Kinetic energy is the energy that an object or thing has in motion. The Elastic potential energy that was stored by winding up each rubber band turned into kinetic energy when the tension and potential energy in the rubber band was released. When the tension was released from the rubber band being wound up around the axel, the potential energy that was stored in the rubber band was released, and turned into kinetic energy, and moved the car forward.
Even though each group was given a basic default car to start with, there were still a lot of modifications that could be done to change certain aspects of the car. These modifications had to do with what type of rubber band was used, the shape of the cardboard, the location of the axel, etc.
Rubber bands on the wheels
One of the most significant changes we made to our car was putting the thickest variant of rubber bands around the edge of the wheels, to create more friction against the ground. One of the biggest problems our car had before this modification is the wheels kept spinning out before they had enough friction against the ground to create momentum and start moving the car forward. After this modification, our car went a total of 22 feet, up from our previous record of 17 feet.
Long, thin rubber ban.
The second important modification we added to our car was the use of the long, thin rubber band as opposed to other thicker or shorter options. As we tested the different types of rubber bands available we found that short rubber bands released their energy too quickly to be able to carry the car a long distance. In addition to this, when we tested the thicker rubber bands, we found that although they are strong and have the most amount of Elastic Potential Energy than any other rubber band, they release that energy too quickly, and do not carry the car far enough. The long thin rubber bands, when wound up, release their potential energy at a slow rate, and move the car a much farther distance, with this modification, our car went 27 feet.
Skewer out the back
Another important modification we added to our car was the skew that came out the back of the car. This helped the car by not only helping the car become centered and balanced, but also help the rubber band have more tension and more elastic potential energy. Before the skewer was added at the back, the rubber band was attached to the cardboard itself. Not only does this create less kinetic energy, it also creates a situation where the car easily can turn and not go in a straight line. In addition to putting the skewer in the back, the rubber band was cause as to be one straight piece of rubber as opposed to a loop, so it could be wound up more around the axel and turn into more kinetic energy over a longer period of time. With this modification, our car went 34 feet.
The Final modification we made to our car was wrapping duct tape around the parts of the axel were the wheels were located, so the skewer could tightly fit in the center hole of the CD. Before this, we were attaching our wheels by putting tape on the surface of the CD and sloppily attaching that to the skewer. This was not optimal, as the wheels were all too often crooked and did not go straight. After we made this modification, our wheels were stable and are car almost always went straight. After this modification, our car went 39 feet.