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Balloon-Powered Racers in 8th Grade Science

Newton's laws of motion seem to work perfectly on the chalkboard, but in real life, we find that surfaces are seldom frictionless and that few moving objects are truly predictable. As a hands-on way to explore how outside forces interfere with Newton's perfect situations, 8th Grade Science students recently built balloon racers, balloon-powered cars that are pushed forward when air rushes backward out of the balloon.

Before starting to build, students reviewed Newton’s laws of motion and considered how the push and pull forces that make objects move will be applied in this project. They planned the elements of their final balloon car design, including how they would connect the wheel to the axle and the axle to the body of the car, what they would use to create the car body and what they could do to reduce friction between the wheels, axle and body of the car. Finally, 8th Graders began constructing their racers, keeping in mind the following parameters: the car must be powered by an inflated balloon, it can be built out of anything, it must be capable of moving, it cannot leave the ground and it must have at least three wheels, made out of a something not originally meant to be used as wheels.

As 8th Graders began to test their models, they began to recognize how friction affects motion and, as a result, how difficult it can be to make something work reliably. They used information gathered in the testing stage to improve their balloon racers and increase their speed in preparation for the final event of this project: a balloon-powered car race!