Moving models always make good science fair projects. The motion involved makes the project more interesting to the judges and the general audience who comes along. the best part of the deal is that if it moves it is usually based on a good scientific principle that can be used effectively in the display part of the project.

This light weight model car is based on the Third Law of Motion as given by Newton. The law states that when a particle A exerts force on particle B, then the particle B exerts an equal force on particle A in the opposite direction. Which basically comes down to saying that every action has an equal and opposite reaction.

What all will you need to make the balloon rocket car? A piece of Styrofoam which is light weight and sturdy for the body of the car. Add some pins to serve as wheel axles and cut out some wheels out of the piece of Styrofoam as well. Make sure that you test the wheels and that they move freely.

Paste a straw down the center of the rectangular body piece of the car model.At one end of the straw attach a balloon that fits well and leaves no space for air to get out. The other end of the straw should jut out enough for you to blow air through the straw into the balloon. Now fill it up and let go. The car will move as the balloon wheezes out the air giving you a science fair project.