Make a Recycled Bottle Balloon Racecar
In this science experiment, kids will build a rocket balloon racecar and explore Newton's Third Law of Motion.
Newton’s Third Law of Motion states that for every action, there is an equal and opposite reaction. In this experiment, when the balloon pushes air out of the back of the car, there is an equal and opposite push that forces the car forward.
This project also presents an opportunity to experiment with how cars are engineered, as kids can work to make their cars move faster, straighter, etc.
- Recycled plastic water bottle - 1 per student
- Recycled plastic bottle caps (all same) - 4 per student
- Large toothpicks or wooden skewers (axles) - 2 per student
- Straws - 6-10 per student
- Balloon - 1 per student
- Decorations as desired
Remove the cap from the water bottle.
Cut the straws so they are just slightly shorter than your toothpicks. Glue or tape them to the bottom of the bottle so that they can hold the wheel axles (toothpicks) in place.
Poke small holes in the plastic caps. Attach one to one end of each of toothpicks. Thread the end of the toothpick without the cap through the straw, then attach a plastic cap to the other end. Be sure all of this is secure and not too wobbly. Now you have a basic car!
To make your car go, you’ll need a force; wind power from a balloon will work nicely!
Tape together 3 or more straws, then securely tape an uninflated balloon to one end.
Make a hole in the top center of the water bottle (with the wheels on the ground) and thread the end of the straws that aren't attached to the balloon through the hole and out the neck of the bottle. The balloon should be above the car; the open ends of the straws should be sticking out through the neck.
Decorate your car as desired. Now you are ready to race!
To race your car, blow up the balloon through the straws then twist the balloon to hold the air in. When you are ready to launch, place the car on the ground, untwist the balloon and let the car go!
Encourage kids to re-engineer their cars to create more wind power (Bigger balloon? More straws? Fatter straws?), more speed (Add fins? Bigger wheels? Less wobble in the wheels?), etc.
In a classroom or group setting, create a starting line and let the kids race their cars together.