Materials

balloon (long skinny ones work best) tape clothes peg straw scissors scrap paper cereal box (or stiff paper) paper or plastic cup (optional) long piece of fishing line (or smooth string) bottle cap or marble (to use as cargo)

Your Task

Design and build a rocket that will transport your cargo.

Guidelines

1. The propulsion, or energy, for your rocket will come from an inflated balloon.

2. Build your cargo container from materials such as paper, a cereal box, or a paper or plastic cup.

   

3. Your rocket will travel along a piece of fishing line, which is threaded through a straw on your rocket. Remember to include the straw somewhere in your design.

4. It is up to you to find the best way to attach the cargo container to the straw and the balloon.

Launching your Rocket

1. Blow up your balloon and use the clothes peg to hold it closed.

2. Tape one end of the fishing line to a wall about chest high. Hold the other end in your hand at approximately the same height.

3. Load your cargo (bottle cap, marble or any other small, light object) into the container.

4. Thread the fishing line through the straw attached to your balloon rocket.

5. Unclip your clothes peg and watch your rocket fly!

Taking it a Step Further

Testing is an important part of engineering. Record how far along the fishing line your rocket went, modify your design, and test it again. Did it go as far or farther than your original rocket?

What’s Happening

When you blow up a balloon, you force air into a small space. Air particles don’t like to be squished (engineers call it "compressed"). The particles want to move to a less crowded area. When you let go of the clothes peg, the air in the balloon rushes out to the lower pressure (less crowded) room. All that air rushing out the back of the balloon pushes it forward. Remember, for every action – air rushing out the balloon opening – there is an equal and opposite reaction – the balloon rocket shoots off down the fishing line.