Potential and Kinetic Energy Car: Two Wheels, Rubber Bands, and Iterations

On Friday, we were asked to design a car that stored potential energy and converted it into kinetic energy.  Using the materials provided, my group designed a car with two wheels made of CDs held to cardboard with a wooden skewer and duct tape.  We launched it with a rubber band.

When tested, it went only about 2 feet, which, honestly, was farther than the majority of the other cars.  I heard someone mention that our car "was a piece of crap and wasn't even a car", which I fully disagree with, because I think it highly unlikely that future cars will have four wheels.  In the picture, the wheels can be seen bending, towards the left, which happened after a few tests.  We set out to find a way for the wheels to support themselves on the road.

The above picture is our redesigned car.  As you can see, we made each wheel out of two CDs, separated with cardboard to make them more sturdy and able to stand on their own.  This car went at least five feet before it swerved off course and hit a curb.  The wheels moved very freely, allowing the vehicle to be able to spin 360 degrees, but proved to be a disadvantage in the distance competition.  If we were to do this again, we would fix the wheels better for better distance, but otherwise, we are happy with our car and the way that it spins so easily.