A balloon-powered car is a great way to learn about kinetic energy, potential energy, conservation of energy and Newton’s Laws of Motion. When you blow up a balloon, it stores potential energy in the form of the stretched skin of the balloon and compressed air inside the balloon. When you let go of the balloon, the stored energy is converted into kinetic energy as the balloon flies around ( some energy is also converted to heat because of friction ). The laws of conservation of energy say that energy doesn’t disappear but changes to different forms.
When you let go of the balloon, the stored energy is converted into kinetic energy as the balloon flies around ( some energy is also converted to heat because of friction ). The laws of conservation of energy say that energy doesn’t disappear but changes to different forms.
We’ve made balloon-powered cars using cardboard before, but this LEGO® version worked well and made it easy to add and remove bits to make the car heavier or lighter.
How to make a balloon powered car
We added a section onto the back of a LEGO car to hold a balloon, blew up the balloon and then watched the car zoom along as the air escaped from the balloon.
I need to spend more time perfecting our design, but this was a good start and gave us lots of ideas for the future.
Balloon Powered LEGO Car
Things to change
Our car fell over quite a lot. I think a lighter, wider car would be better, as it would be more stable.
Another idea is to place a straw into the end of the balloon to make it easier to blow up each time.
Newton’s Laws of Motion
Our balloon-powered car is also a great example of Newton’s Third Law of Motion.
For every action, there is an equal and opposite reaction
Air is forced out of the end of the balloon, which means there must be an equal and opposite reaction pushing the car forward!
You can also see this in action with a water powered bottle rocket.
Balloon Powered Car Extension Activity
Design a LEGO® car first, then consider the features the car needs to work well, considering the above points.
You can also make a balloon powered car from cardboard and milk jug tops!
More LEGO Activity Ideas
Design, build and test a LEGO parachute or try one of my other science experiments using LEGO.
Last Updated on February 25, 2025 by Emma Vanstone
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Hayle Larimore
do you think I can turn the scribble bot into a middle school science project