How does elastic potential energy turn into kinetic energy?
Elastic potential energy comes from applying force to an elastic object, such as a rubber band. The energy is stored until the force is removed from the object and the object goes back to its original shape. For example when you wind up a rubber band car you are using your hand (the force) and applying it to the rubber band by winding the wheel. When you let go of the wheel the rubber band springs back to its original shape, propelling the car in the process converting it into kinetic energy.
What were your 4 most important modifications?
The first modification we made was changing the way we taped the wheels. Instead of only sticking the wooden stick through two pieces of tape, we circled the stick with tape, and it made it a bit more stable. We got 5ft., compared to 3ft, which we got with no mods.
The second major modification we made was taping the wheels differently again, this tome using vertical strips of tape, instead of circling around the wooden stick on the outside of the CD to make the wheels sticker easier to the axle. We also cut off the sides of the cardboard square to reduce friction and make the ride smoother. When we added this modification to the mix, we got 14ft.
For our third mod, we decided to try to slim our car more than last time. This meant using less tape more efficiently, and cutting off more cardboard than last time. This time, we also cut off the center-top part of the cardboard, as well as using less tape in the inside part of the CDs. We also added tape to the top part of the cardboard, to reduce friction even more. With this mod we got up to 17ft., 3 more feet than last time
The most recent (and best) mod was basically a complete make over. We taped the wheels completely differently, by rolling tape around the stick, then putting the roll through the CD hole. Not only was this more stable than before, but it was also much easier. Also, instead of cutting the cardboard piece, we added another wooden stick to reduce friction even more. The last modification we made was putting the rubber band on the second wooden stick, and then rolling it around itself on the other stick. With these final modifications, we got 22ft., our best so far.
Velocity & Acceleration
We used video physics to track the car in motion so we could see how fast the car went, and how fast it accelerated over certain points in time. The video needed to be taken at this angle and with a yard stick in the background because we needed to measure how long a meter is in relation to the video, so we could see how many meters it went.
In the video we shot it from a different angle than usual, because we used a meter stick to show how long a meter was.
On the charts above, they show the velocity and acceleration of the car.
We know that velocity is the speed of something in a given direction at a certain period of time. We pinpointed those certain points in time and converted them in to a graph. The top one shows the acceleration at certain point in time. A= change in velocity/time. So on the bottom one shows the velocity or wether the car is accelerating or decelerating at a certain point in time. V= distance/time.