Design and build balloon-powered LEGO cars that will blast off with the help of the air from the balloons! There are unlimited ways to build the cars and your kids will love racing them to see which one will go farther.
We just moved for the 5th time in 6 years, so most of our items are all in cardboard boxes.
I had strategically put some of my kids’ toys aside in a specially marked box. This box arguably was the most important box of all because it gave my kids something to play with right when we move into the new house.
And of course, I packed lots of LEGOs!
I am so glad I did that. You can do so much with LEGO blocks, including designing a balloon-powered LEGO car and a LEGO zip line for the minifigures!
This LEGO balloon car project is easy and simple, and it’s a fun time for the entire family! Even preschoolers can design and build their own LEGO race cars and participate in the activity. My daughter also enjoyed being the referee and watched the finish line closely to see whose car was the fastest.
Ready to race your balloon cars? HERE … WE … GO!
How to Make LEGO Balloon-Powered Cars
1. Have your child create and build his/her own LEGO car.
2. Show your child how you can build a hole to stick the balloon through.
3. Blow up the balloon and hold the end shut while you place the cars on the ground.
4. Let the LEGO cars go and see how far the car can travel!
5. Measure how far the car went and record the distance in the free balloon-powered LEGO cars worksheet under “Car 1”.
6. Blow up the balloon and see how far the car can travel this time.
7. Record the result under “Distance 2” in the worksheet.
8. Make the necessary improvements and repeat steps #4-#7 with “Car 2”.
9. Tweak your LEGO car one more time and repeat steps #4-#7 with “Car 3”.
10. Determine which car has the best design and why and record your observation and reflection on the free balloon-powered LEGO cars worksheet.
Balloon Car Design Tips
When I first tasked my son to design his own LEGO balloon-powered car, I thought I was going to build most of the car. Surprisingly, he told me that he got this and built the race car on his own. Mommy was proud.
His LEGO car had a simple design, but there is no need for more. In fact, if you build too fancy of a car, the weight of the LEGO bricks might impede the car from going far.
We tested our designs before racing our cars. My son’s LEGO car had no issues with the air from the balloon pushing it forward. My car, on the other hand, kept flipping over instead of staying upright on its wheels.
The reason that the balloon was able to propel my son’s car without any issues is that my son’s car was low, flat, and long. Meanwhile, my car was tall and short.
Think of a race car versus an SUV. So when we apply force to the car with the air from the balloon, the air knocked my car over instead of pushing it forward.
Another design issue we noticed was that if the hole where the balloon went was too big, the balloon would fall out or change directions. To make the car go straight, we made the hole smaller. Here is a picture of what we ended up with:
To summarize, here are some tips for building your balloon-powered car:
- Make sure the base of the car is wide and long enough. A short, narrow car may not be able to handle the force applied on the car from the balloon.
- Do not build the car too tall. A lower car means the center of gravity is lower to the ground, which means the car is less likely to flip when turning at high speeds.
- The hole for the balloon should be as small as possible so the balloon doesn’t fly out when released.
If your LEGO balloon car is not working, be patient and try again! It may take a few tries. My first attempt certainly did not work!
I changed my car design to imitate my son’s LEGO car and we were ready to go.
The Science Behind Balloon-Powered LEGO Cars
While you can do this activity just for fun, there is an opportunity to teach your child the physics of force and motion!
Newton’s first law states that “every object will remain at rest or in uniform motion in a straight line unless compelled to change its state by the action of an external force.”
Show your child how the LEGO car by itself will not do anything. It’s not until you release the air from the balloon and apply external force on the car that it starts to move.
For elementary school kids, you can also start explaining the concept of friction to them. According to Newton’s first law, the balloon car should continue moving at a constant speed in a straight line. However, the force of friction between the wheels and the floor slows down the car and causes it to come to a stop.
Here are some experiments you can do with your child:
- Blow up the balloon bigger. Does the car go faster? Farther?
- Add some more LEGO bricks to the car. How does the extra weight impact how far the car can travel?
- Try racing the cars on a different surface (i.e. carpet vs. wood floor).
- Place the balloon higher up or lower down on the LEGO car. How does the placement of the balloon impact how the car moves?
Final Thoughts on the Balloon LEGO Car Activity
If your kid is not into LEGO yet, this is a great activity to get him/her interested. You can do this over and over again with different car designs. Let your kid’s imagination run wild when building the cars and take lots of pictures to document his/her creativity. You can even try different types of balloons!
This balloon-powered LEGO car activity is also awesome for playdates. I bet the kids would have a blast racing their cars with their friends!
This balloon-powered LEGO car activity is part of the 30-day LEGO STEM challenge. Download the free LEGO challenge calendar for a month of LEGO STEM fun.
YOU MAY ALSO LIKE: Free Printable 30-Day LEGO STEM Challenge Calendar
Want this activity in an easy-to-print file? I have compiled 5 super fun LEGO STEM activities for kids in a printable PDF.
Each activity includes a list of supplies, step-by-step directions, an explanation of the science behind the activity, and different extensions based on the science concepts.
The ebook includes:
- Balloon-Powered LEGO Cars
- LEGO Zip Line
- Penny LEGO Boat Challenge
- LEGO Volcano
- LEGO Plinko Board