Balloon-powered cars are fun to build and even more fun to play with. In this project, I will be challenged to build and test my own balloon-powered car. The purpose or aim of my project is to make the balloon-powered car move. The potential energy inside the balloon is converted to kinetic energy, or energy of motion, of the fast-moving air through the opening. Because the air is pushed our rapidly backwards, there is a reaction force that pushes the balloon forward.