Let’s make one balloon rocket with things you have around the house to explore Newton’s third law. This simple balloon science experiment is a rocket that can be built in your backyard or playground with just a piece of twine or fishing line, a water bottle, tape, a straw, and a balloon. Kids of all ages will love this science activity, including older kids. I’m doing it with preschoolers today.
Balloon rocket for kids
My kids are fascinated by anything related to space and real rockets (even if it’s not directly related to Star Wars). Today we bring NASA into our backyard through the magic of fishing line, straws and balloons.
It’s like Apollo 13, but without the danger.
Related: Science projects for kids
What is Newton’s third law?
Sir Isaac Newton is known for his Three Laws of Motion which were published many, many years ago in 1686. His first law is about an object at rest, his second law is about how force equals mass times acceleration, and his third law of motion:
For every action there is an equal and opposite reaction.
Let’s build a balloon rocket to explore how one action (the full balloon deflating) creates an opposite direction (the balloon rocket moves)!
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How do I make a balloon rocket?
Materials required to build a balloon rocket
Instructions for building a balloon rocket
Gather your supplies and cut the straws into smaller pieces.
Place your fishing line between two objects in your yard, 80 to 100 feet apart, and tie one end of the line to the secure object.
Before attaching the second end of the line, thread the fishing line through two of the straws so they can slide down the line.
Take the water bottle and cut off each end so you have a 3-4 inch ring. Glue this ring to one of the straw segments.
Next, get your balloons.
Note: Please learn from my mistake. When I went to the store to buy long balloons, I bought the ones that are for making balloon animals. When I got home I realized that without some kind of pump these are impossible to blow up. I needed bigger balloons! From here I’ll show you how to do this using round balloons, which aren’t nearly as effective as traditional long balloons or inflated balloon animals!
Blow up one balloon, then hold it in the ring to keep the air in while you attach a second balloon.
With the right balloons and better coordination, the second can be positioned to stop the first from escaping air. Each balloon contains different amounts of air.
Balloon Rocket Launch
Release the second balloon… the air will escape! The balloon rocket is moving! We saw the rocket fly!
The second balloon propels the rocket and the rocket flies forward and then as it gets smaller the first balloon takes over.
Reusable balloon rocket
We launched the balloon rocket over and over again. Every time I watch the thrust of the air currents created by our rocket engine.
In subsequent launches I only used one balloon because it was easier to set up and I had very enthusiastic astronauts.
Why the Balloon Rocket works
Why is this happening? For every action there is an equal and opposite reaction. This principle, observed by Newton, lies at the heart of rocket science (in this case, the balloon rocket). The air exiting the balloon pushes the rocket forward in the opposite direction. The force of the escaping balloon air is the same as the propulsive force propelling the ride.
Printable instructions balloon rocket experiment.
Questions Kids Might Have About Newton’s Third Law
- What is Newton’s third law?
- Can you explain it in simple words?
- Who is Newton and why is he important?
- How does Newton’s third law work in everyday life?
- Can you give me an example of Newton’s Third Law?
- Does this law work for everything or just some things?
- What happens if I push or pull something?
- Why do things move when we push or pull them?
- If I push my friend on a swing, does the swing push back?
- How does this law help us understand how things move?
Keep in mind that kindergarteners and first and third graders may not fully understand the scientific concepts behind Newton’s Third Law. So it’s important to provide simple, age-appropriate explanations and examples to help them grasp the idea.
How do I make the balloon rocket fly faster or farther?
- Increase the air pressure in the balloon: Fill the balloon with more air to increase the pressure inside. More air escaping the balloon creates more force, propelling the rocket faster and farther. However, be careful not to over-inflate the balloon as it may burst.
- Use a larger or longer balloon: A larger or longer balloon can hold more air, meaning it has the potential to generate more force when the air is released. Experiment with different balloon sizes to find one that optimizes speed and distance.
- reduce friction: Make sure the string or line used for the rocket’s path is strong and smooth to minimize friction. Lubricate the straw with some washing-up liquid or cooking oil to make it easier to slide along the string.
- Optimize the rocket: Make sure the straw or tube connecting the balloon to the string is lightweight and has a low profile to reduce drag. You can also tape the neck of the balloon in a straight line along the straw to minimize drag.
- Optimize angle: Experiment with different angles of cord or line to find the most efficient trajectory for the balloon rocket. A slightly upward angle can help the rocket fly farther.
- Use a nozzle: Attach a small nozzle or straw to the opening of the balloon to control the air release more effectively. This can help direct the outflowing air more precisely, creating more thrust and potentially allowing the rocket to fly faster and farther.
Challenging kids to make adjustments to their balloon rocket design is a great way to learn about the factors that affect a balloon rocket’s speed and distance.
Related: Use our science methods worksheets for kids to test different balloon rocket designs!
Why does the air in the balloon move the rocket?
The air in a balloon wants to escape due to the difference in air pressure between the inside of the balloon and the outside of the balloon. When you inflate a balloon, you push air molecules into the narrow space inside, increasing the air pressure inside the balloon. The balloon’s elastic material stretches to accommodate the increased air pressure.
The air pressure inside the balloon is higher than the air pressure outside the balloon, creating a pressure differential. The air molecules naturally try to move from an area of high pressure (inside the balloon) to an area of lower pressure (outside the balloon) to equalize the pressure difference.
When you release the balloon opening and let the air out, the high-pressure air in the balloon rushes out through the opening, creating an action force. As the air escapes, it exerts a force on the air outside the balloon.
According to Newton’s third law, the force of the outflowing air has an equal and opposite reaction force. This reaction force acts on the balloon, propelling it in the opposite direction of the outflowing air. The balloon moves forward by this force and works like a rocket.
This science balloon rocket activity demonstrates Newton’s third law of motion in action. Newton’s third law states that for every action there is an equal and opposite reaction. In our balloon rocket activity, this principle can be observed when the air in the balloon is released, causing the rocket to move in the opposite direction.
If you blow up a balloon and then release it without tying the end, the air in the balloon will spill out. When the air is pushed out of the balloon (the action), it exerts an equal and opposite force on the balloon itself (the reaction). This force propels the balloon in the opposite direction of the outflowing air, causing the balloon to propel itself forward like a rocket.
This balloon rocket science experiment is one of my favorite examples of Newton’s Third Law in action! It shows how the force of the air escaping from the balloon results in an equal and opposite force propelling the balloon forward. This hands-on activity can help children better understand the concept of action and reaction in a fun and engaging way.
Is it safe to craft and play with balloon rockets?
Yes! It is generally safe to build and play with balloon rockets as they are powered by balloons. Of course, younger children who could put a balloon in their mouth should not participate without adult supervision as it poses a choking hazard. The other less obvious danger is allergies. Some children are allergic to latex, which is a common balloon material. If necessary, you can find latex-free balloons.
More rocket fun from the Kids Activities Blog
Did you have fun with Newton’s third law and your homemade balloon rocket?