The student is concerned about pollution caused by gasoline-powered cars and wonders if balloons could power cars instead. They conduct an experiment to test how far different types of homemade cars move when blown by balloons. A plastic car and Lego car are each tested 4 times with balloons blown to different strengths. The results show the Lego car, being heavier, travels farther each time due to greater momentum keeping its wheels spinning longer. The student concludes that a car's weight impacts how far it can move when powered by balloons.