Balloon Rocket: Experiment

“Balloon Rocket” is a fun experiment that demonstrates how propulsion works using a simple balloon rocket.

Materials Needed:

  • Balloon
  • Drinking straw
  • String
  • Tape
  • Scissors
  • Measuring tape

Steps to launch a balloon rocket:

  • Cut a piece of string about 4 feet long and tape one end to the leg of a chair.
  • Thread the straw onto the string. Tie the other end of the string to a stationary object nearby like a desk.
  • Blow up a balloon and pinch the end shut to stop the air from escaping. Don’t tie it off!
  • Without letting any air out, tape the blown-up balloon to the straw with the mouth end facing you.
  • Release the balloon, and see how far it goes!


Science Behind Balloon Rockets

The science behind a balloon rocket involves two main concepts: Newton’s Third Law of Motion and the principles of air pressure.

Newton’s Third Law of Motion: 

  • This law states that for every action, there is an equal and opposite reaction. 
  • When you blow up the balloon and then release the opening, the air rushes out of the balloon in one direction.
  • The air pushing out of the balloon creates an equal and opposite force that pushes the balloon forward. This is the principle of propulsion that allows the balloon rocket to move.

Air Pressure: 

  • When you blow up a balloon, you put a lot of air inside, making the air push hard against the balloon from the inside. 
  • When you let go of the balloon, the air rushes out quickly because it wants to be the same everywhere. 
  • This rush of air pushes the balloon forward, just like when you blow up a balloon and let it go, it flies around the room 

Size of the balloon: A larger balloon can hold more air, providing more thrust to the rocket. 

Launch Angle: Launching the rocket at a slightly upward angle can help it go farther.

By experimenting with these factors, you can make your rocket go faster and farther.


Fun Facts

Here are some interesting facts about rockets:

  • The force that pushes a rocket into space is called thrust. It’s created by burning fuel and shooting the hot gas out of the back of the rocket.
  • Rockets can be used for more than just space travel. They’re also used in fireworks, to launch satellites into orbit, and to study the Earth and other planets.
  • The most powerful rocket in operation today is SpaceX’s Falcon Heavy, which can lift over 140,000 pounds (63,500 kilograms) into orbit.



Let’s quickly recap what we learned about the science behind balloon rockets:

  • What are the two main concepts behind a balloon rocket? Newton’s Third Law of Motion & Air Pressure
  • What is the force that pushes the balloon rocket forward? Propulsion
  • What happens to the air pressure inside the balloon when you let go of the opening? Decreases as the air rushes out
  • What two factors can you experiment with to make the balloon rocket go faster and farther? Size of the Balloon & Launch Angle
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