balloon powered car activity with kids

Easy Balloon Powered Car Science Project

Have you tried this fun activity yet? Making a balloon-powered car is simple and a creative way to learn about forces. 

Thank you to Leah from DIY Creative Home Education for sharing this activity with us! Her kids had so much fun with their balloon cars.

You can find more of Leah’s car-themed activities here.

balloon car science project

What you’ll need to build your balloon cars

This activity is quite versatile, because you can build your own cars from scratch or simply attach a balloon engine to a toy car you already have. 

If you’d like to try making your own balloon car, you might need:

  • Recycled materials like plastic bottles, egg boxes, cereal boxes etc.
  • Other materials (wooden kebab skewers, straws and so on)
  • Materials to hold your car together (rubber bands, tape, glue)
  • Scissors
  • Anything you want to decorate your car with (stickers, colouring pencils, markers, colourful tape)

For your balloon engine (which can be attached to a toy car you already have), all you need is:

  • Balloons
  • Rubber bands
  • Drinking straw or candy floss cone
  • Tape

If you’re using a toy car, small metal or plastic cars work well. You can also build your own out of toy building blocks. 

How to do this balloon car project at home

 1. If you’re making your own balloon racer, first build your car. You want it to be as light as possible – if it’s too heavy, the force of the air leaving the balloon won’t be strong enough to push the car forward!

You also need to make sure it has as little friction as possible. Check that the wheels turn smoothly and that there is nothing hanging down that will drag along the ground.

Leah and her boys found that their homemade cars were too heavy to move much when they released the balloons. However, when they transferred their balloon engines to toy cars, they worked brilliantly!

For your balloon propelled car, you might want to make wheels out of large bottle lids or cardboard. To connect the wheels to the car, you can use wooden kebab skewers (just be careful of sharp points!).

Experimenting with the best balloon car design

2. Once you’ve built your car or chosen which of your toy cars you want to use, you need to create a balloon engine.

Take a straw or candy floss cone and attach a deflated balloon tightly onto one end using a rubber band.

If you want to be extra sure that the balloon will stay in place and that there won’t be any leaks, you can also wrap some tape around the mouth of the balloon and the straw. 

However, if you do this it will be harder to swap out the balloon for a new one if you need to later on.

3. Now attach the balloon engine to the car using tape. Don’t tape down the balloon – you want that to be able to expand as you blow it up. Just add tape to the straw or candy floss cone.

4. Blow through the cone or straw to inflate the balloon. You can hold a finger over the mouth of the straw/cone to keep the air inside the balloon until you’re ready to let go.

Once you have the car in position somewhere flat, release the balloon and watch your car (hopefully!) shoot forward!

A working balloon car engine design

Questions to ask kids about their balloon powered toy car

  • If you made your own car first, did the experiment work? What could you do differently next time to make your car go faster (or go at all!)
  • Do you think the size of the balloon would make a difference in this activity? Why or why not?
  • What problems did you come across during this experiment? How could you fix these next time around?
  • What would happen if you did this experiment on a slope facing downwards? Can you explain what you’d expect to see and why?

A simple balloon car experiment explanation

 This activity is a fun way to explore forces, but how does it actually work?

The reason the car moves forward when you release the air from the balloon is because of Newton’s Third Law of Motion. This states that for every action, there is an equal but opposite reaction.

In this case, the air rushes out of the balloon and pushes against the air behind the car. The air behind the car pushes back, and this moves the car forward.

The balloon has been stretched by being filled with air. This creates something called potential energy. As soon as it can, it will shrink back down to its original size. 

When it releases the air, the potential energy it has been storing turns into kinetic (movement) energy. The car moves forward.

STEM cardboard balloon car activity

We hope your kids have had fun learning how to build a balloon powered car! We think they’ll also love discovering how to make a catapult out of lolly sticks.