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By Audra D.

Get ready to blast off with this month’s Simple Science experiment! This five-step balloon rocket project can be completed with materials you likely have at home. Balloon rockets are a great way to learn about air propulsion and thrust, the same scientific concepts real rockets use. You can customize the variables in this experiment for hours of exploration. Check out these titles on Hoopla to continue the fun:  Rockets, Inflating A Balloon, and The Great Balloon Hullaballoo.

Materials needed

  • 1 large smoothie straw
  • 1 balloon 
  • Approximately 8-10 ft of string
  • Tape 
  • Something sturdy to tie your string to

Instructions

  1. Tie one end of your string to a chair, doorknob, or another sturdy object. You can use anything stable that you can get the string around!
  2. Lace the free end of your string through the middle of the straw.
  3. Pull the string tightly and tie it to another support in the room that is the same height. Remember this can be a chair, doorknob, or anything else sturdy. You don’t want any slack in your string, meaning you don’t want the middle to dip down, so pull tight!
  4. Blow up your balloon but do not tie it closed, just pinch the end together. While still pinching it, tape the balloon to the straw.
  5. When you are ready, let go and watch your rocket fly! Repeat the experiment in different ways using the questions below.

Questions to ask

  • Does the amount of air in the balloon affect how far it goes? Try blowing the balloon up halfway to see the difference. What about blowing it up as big as it will get? 
  • Does the length of the straw affect the speed or distance? Cut your straw in half and see what happens.
  • Does the angle of the string affect how fast the balloon can go? Tie the string to two things that are different heights and repeat the experiment.

How it works

Your balloon rocket uses the same forces as real rockets use to fly into space! When the air flows out of the balloon it creates a forward motion. This force is called thrust. Thrust is a pushing force that requires energy. The air rushing out of the balloon is exerting a force on the balloon itself, propelling it forward. In a real rocket, thrust comes from the force made by the burning rocket fuel.

Check out this video tutorial from SciShow Kids on how to create a Balloon Rocket!

Audra D.
Adult & Teen Librarian

Audra D.


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