News and Features - NASA's Jet Propulsion Laboratory

What's New At Pacific Science Center

EurekAlert! - Science Reporting for Kids

Friday, June 3, 2011

Summer Fun: Balloon Dragsters



Who can build the fastest car? Use the directions below to build your vehicle, test it, then challenge your friends to a race. Just keep it on the track, okay?
Materials:
Piece of cardboard, 6 x 10 inches
4 straight pins
Colored markers or crayons (optional)
Flexible straw
Tape
Balloons (un-inflated)
What you Do:
Make dragster parts first. Cut 3x4 inch piece of cardboard. This will be the body of your dragster. Cut four circles, each with a 2 inch diameter, for wheels. Use a pin to poke a hole in the center of each wheel and then set the wheels aside. Decorate parts if you like.
Bend the flexible straw into an L-shape. Lay it lengthwise in the middle of the dragster’s body, with the straw’s mouth-end sticking up near the front of the car and the opposite end extending past the rear of the car. Tape the straw in place.
Put the mouth of the balloon over the mouth of the straw. Tape it in place. Just to test your tape job, blow into the open end of the straw to make sure you can inflate the balloon. If it fails, try re-taping the balloon to the straw.
Attach the wheels to the dragster body using a pin for each wheel. Test it to make sure it rolls. Make adjustments if you need to.
Blow into the straw until the balloon is half full of air. As you take your mouth off the straw, quickly block the end of the straw with your finger to keep the air in. Then let go of the straw and watch the dragster take off.
Try different sizes and shapes of balloons. Vary the amount of air in the balloons. What other modifications can you make and what effect do they have? (change the size of the wheels, or shape of body). What makes the fastest dragster?

What’s going on? Dragsters are a special kind of race car. They use the principles of rocket science to move in a straight line as fast as possible. Rocket engines and balloon dragsters work according to Newton’s Third Law of Motion. That law says that for every action (force) there is an equal and opposite reaction (force). In your dragster, the balloon pushes air through the straw—action—so the dragster moves forward—opposite reaction.

We’ll put out more fun ideas through the summer. Hey, and keep your eyes peeled for other cool stuff. We’d love to hear your ideas! You can contact Amy Oliver at AmyROliver@gmail.com.