Make Your Own Balloon-Powered Car!
Ready, Set, ZOOM!
Printable instructions
At Half Pint Co., we love hands-on experiments that make learning fun—and this Balloon-Powered Car is a perfect mix of creativity, engineering, and play! Using Newton’s Third Law of Motion, kids can build their own mini race cars using simple household materials.
This is an excellent S.T.E.M. activity for budding engineers and scientists and best of all? You can build it at home!
What You’ll Need:
A push pin (for making small holes)
Bottle cap × 4
Cardboard rectangle (ours was 7” x 4”)
Straws x 3
Bamboo stick x 2
How to Build Your Balloon-Powered Car:
Carboard rectangle with straws attached.
Step 1: Make the Wheels
Ask a grownup to use a push pin to poke a hole in the center of each bottle cap—these will be your wheels.
Step 2: Build the Axles
Wheels and axels for the balloon-powered car.
First, take your cardboard rectangle and attach two straws with tape about l" from each end. The straws should be about the same length as the cardboard.
Next, attach a bottle cap wheel to only one side of the bamboo stick. Place your bamboo stick through the straw so the end pokes out the other side. Attach a wheel to the other side of the stick. Repeat with the remaining stick and wheels. Flip your car over and make sure it's moving well. Adjust your wheels if needed.
Step 3: Prep the Balloon
Prepping the balloon for the balloon-powered car.
Then, place your remaining straw about 1" inside the balloon. Use electrical tape to attach the balloon and straw. Make sure it is secure by blowing up the balloon with the straw. If needed, add more tape so no air gets out.
Step 4: Secure the Balloon to the Car
The balloon-powered car is complete!
Finally, use tape to attach the straw to the top side of the car. Place the balloon so the straw is hanging off the board's edge and the balloon is toward the middle.
Blow up your balloon and hold the straw while you place it on the floor.
Release your finger from the straw and watch the car race around!
Step 5: Ready, Set Go!
Blow air into the straw to inflate the balloon, pinch the end shut, place your car on a smooth surface… and release! Watch as the escaping air propels your car forward!
What’s Happening Here?
(The Science Behind It! )
This experiment demonstrates Newton’s Third Law of Motion: For every action, there is an equal and opposite reaction.
The air rushing out of the balloon pushes backward, which in turn propels the car forward!
This is the same principle that rockets and jet engines use to move—pretty cool, right?
Share Your Cars with Us!
We’d love to see what you create! Tag us on Instagram @half.pint.co to show off your balloon-powered race cars.
Keep Exploring!
More DIY S.T.E.M. fun here.
Come to a live event!
Did you enjoy this activity? Are you in the Twin Cities area? We’d love to see you at one of our upcoming free, family-friendly events!
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