Balloon Rocket Experiment

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Author: Alex Jacobsen
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Summertime Science

You need to send a message to home from your tree house, but it’s too windy to send a paper airplane! Fortunately, you have a taut clothesline and a supply of balloons from last week’s birthday party. How can you make a balloon rocket, and how can you make it travel as far as possible?


How does the volume of air in a balloon affect the distance it travels?


  • Rubber Balloons
  • Binder clip
  • String or Thin Rope
  • Straws
  • Tape
  • Cloth Tape Measure
  • Two Posts (At least three feet tall and fifteen feet apart)
  • Paper
  • Pencil
  • Graph paper
  • Helper


  1. Tie the string or rope to one of the posts at the height of at least three feet. Leave the other end loose.
  2. Cut some straws into lengths that will fit on your balloon. One third of a straw is usually a good length.
  3. Inflate a balloon and seal the air inside by folding the neck over once and clamping it shut with a binder clip.
  4. Measure and record your balloon’s circumference by wrapping your tape measure around the balloon’s widest point. You might need your helper to lend a hand:

Balloon Rocket Diameter Diagram

  1. Keeping the balloon’s opening shut, tape a straw to your inflated balloon. Make sure the straw and the nozzle of the balloon are parallel to each other.
  2. Thread the loose end of your string through the straw so that the neck of the balloon is facing towards you.
  3. Pull your string taut and line it up with your second post. Measure a point off the ground that’s the same height as the knot holding the other end of the string to the first post. Be sure to hold the string at this height whenever you’re conducting a balloon launching trial. Why do you think holding your end of the string at the same height is important?

Balloon Rocket Diagram

  1. Count down to zero, and let the rocket fly! Have your helper use the tape measure to measure and record the point on the string at which the balloon stopped.
  2. Repeat steps 5-8 with two more balloons inflated to the same circumference as your first balloon.
  3. Average the distance traveled for all three trials.
  4. Repeat steps 5-10 with three balloons inflated to a circumference 5cm greater than your first balloons were.
  5. Keep conducting trials using balloons inflated to progressively bigger circumferences. You can use a table like this as a guide:
  20cm 25cm 30cm 35cm 40cm 45cm
Trial 1            
Trial 2            
Trial 3            
  1. Using a sheet of graph paper, plot your trials on a line graph. The x axis should be circumference in centimeters. The y axis should be distance travelled in feet.
  2. Look at your graph. What is it telling you?


 If you had a large enough difference between your smallest and largest circumferences, you should see the average distance traveled go up very quickly as the balloon’s circumference increases.

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