Balloon Powered Race Car

Balloon Powered Race Car Project


  • to create a balloon powered race car for maximum speed between 0 and 3 meters
  • to incorporate Newton’s Laws of Motion

Part 1 (20 points)

Newton’s three laws seem to work perfectly on the chalkboard, but in real life we find that surfaces are seldom frictionless and that few moving objects are truly predictable.  This is because outside forces interfere with Newton’s perfect situations.  Balloon racers rely on Newton’s third law of motion.  As the air rushes backward out of the balloon it pushes the car forward in the opposite direction with an equal force.  Your job is to make the most of this force!  While building balloon racers we will discover how difficult it can be to make something work reliably.


  1. Wheels –plastic bottle caps, cd’s, spools of thread; you may cut-out your own wheels from paper, plastic, Styrofoam, metal, etc…
  2. Axle rod – The rod is the part attached to two wheels so they turn in unison. Small diameter plastic straws, coffee stirrers work well.  You may cut them or use a material of your choice.
  3. Axle housing – You slip the rod through the housing and attach the housing to the car. Regular plastic straws work well. They can be cut to any size you want.
  4. Body – anything you want, popsicle stick, cardboard, styrofoam, balsa wood etc… 
  5. 9” Balloon
  6. Various materials to construct the racers, all materials must be “stuff” lying around your house or school (except for tape or glue)!
  7. tape and glue
  8. You will receive:

–          a 9-inch balloon

–          straws

–          (if you need materials or ideas let me know and I will help you out)

  • Design and contest rules
  1. No kits or pre-made designs may be used. The car must be the individual’s invention.
  2. The car must be completely powered by the balloon.
  3. All self provided materials must not be purchased specifically for this contest; use items you have around the house or if not, ask me for materials from school.
  4. The balloon can be inflated to any size as long as it does not burst. Should the balloon burst during the run, it will count as an official run.
  5. Only 9-inch (22.5 cm) latex balloons will be used during the competition.
  6. The car must have a minimum of three wheels.
  • Judging:
  1. Cars will be tested on a smooth flat surface. Distance is measured from the starting line to the farthest point of travel, utilizing a straight line to connect the two points.
  2. The car must move a minimum of 3 meters, in order for the score to be recorded.
  3. The score will be based on the speed of the car. In case of a tie, a race will be held.

Good Luck!

Part 1 continued: Building the Car : Tips and Tricks

  • The first thing to do is choose the material to build the body of the car.  The body should be both light and sturdy, for this reason styrofoam makes a very good body.  It is also important to design a body that is long enough.  Short cars tend to spin out more often than longer ones.  A good car should be about 30 cm long.
  • The second thing to do is build and mount the wheels.  Wheels can be made out of about anything that is round, such as CDs, caps, and lids.  The hard part, however, is getting them mounted straight with little friction.  If the wheels are not mounted straight or are not free to spin smoothly, the car will not perform.
  • Once the wheels are mounted on the body it is time to put a balloon onto the car.  Having the balloon attached to a pen barrel so that the air comes out in a smooth manner helps.
  • If the car has a sturdy but light body, free moving wheels and a good power supply, you are well on your way to being a balloon racer champion.
  • Tips for attaching balloons to tubes:
    • Make sure tube or straw goes all the way into the balloon (past the neck part and into the body) – this ensures that the balloon won’t fold and stop up the tube
    • Wrap the balloon around the tube end so that it basically seals and you end up with the balloon tightly wrapped around the tube with a flap of balloon left over on one side. Carefully fold the flap around the tube, keeping the seal good, and tape the flap to the rest of the balloon
  • Also, making sure the axles are parallel is key

Part 2 (10 points)

Sketch a diagram of your car on a separate piece of paper. Include the following;

  1. overall length of car
  2. overall width of car
  3. diameter of wheels
  4. length of axle housing
  5. length of axle rods
  6. Force arrows of all forces acting on the moving car
  7. Force arrows must be labeled

 Part 3 (20 points)

Each group member will write a five paragraph typed paper, describing how they used the science and       Newton’s Law’s of Motion to complete their project.

  • First paragraph- Describe the problem you are trying to solve. What are the rules you need to follow to complete the project?
  • Second paragraph- Describe how you solved the problem. What types of problems did you run into?  What process did you go through to complete your car successfully?
  • Third paragraph- Describe what build methods worked best. Specifically, discuss the competition; what traits made the fastest car? What would you have done differently?
  • Fourth paragraph- Describe how Newton’s Law’s of motion were at work on the car while in motion and during construction/design of your car. (Friction, Momentum, Forces etc…)
  • Fifth paragraph- In conclusion, describe what you learned by doing this project. Discuss the best parts of the project and the most difficult moments. Also, what would you do differently next time?

What you must hand in:

  1. Sketch of your car as described in Part 2
  2. 5 Paragraph paper as described in Part 3
  3. Complete answers to questions in procedure section Part 4
  4. Balloon racer car “ready to race” on race day.  Part 1
  5. Cover for written material

Procedure (you can use these steps as a guide or try to do it your own way):

1. Cut the bend off two regular plastic straws.

  • These are called the axle housings.
  • The housing should be slightly shorter than the axle rod (step 2).
  • Measure the length of your axle housing and record your measurement in cm. ______________cmAxle rods:
  • Measure the length of your axle rods, record your measurements in cm. ____________cm
  • Insert the axle rods into each axle housings.
  • You may want to glue one wheel onto each axle rod, then place the axle housing over the axle rod and glue the other wheel onto the axle rod.
  • Center axle housings onto the popsicle stick.
  • Put one axle in front and one in the back.
  • Use the hot glue gun to fit these pieces into place.
  1. Try your car.
  • Put it on the ground.
  • Give it a push.
  • Does it roll, easily?
  • If not, check to make certain your axle rod is not rubbing on the inside of the axle housing.
  • If rubbing is a problem, go see T. Joyce
  • Use the third regular-sized straw and insert about 2 cm of the straw, near the bend, in the opening/neck of a balloon (22.5 cm or 9 inch).
  • Secure the balloon in place by looping a small rubber band several times around the neck of the balloon containing the straw.
  • Make sure the rubber band does not crush the straw.
  • Tape the straw to the car – leave enough straw to blow into the balloon and fill the balloon with air.
  • To move the balloon car, blow into the free end of the long straw until the balloon is the desired size.
  • Quickly squeeze the opening of the straw to keep the air from escaping from the balloon.
  • Position the car, balloon end in the front.
  • The car should begin to travel as soon as you remove your finger from the straw.
  • If your car moves sluggishly or not at all, it is because the axle is rubbing and you did not adhere to the requirements of Step 6.
  • Use a ruler to measure the:
  • Overall length of your car (cm): _________
  • Use the digital scale to measure the overall weight of your car (grams): _________
  • Did you fill-in all the blank spaces on the previous 10 steps?

   Test your car.

  • Inflate the balloon without breaking it.
  • Hold the nozzle shut until you are ready to race.
  • Release the nozzle and start the stopwatch.
  • Stop the watch when the balloon runs out of air.
  • Mark the spot on the floor where that occurred.
  • Record your results on the data table.

Test Your Car


Your time

in seconds

Distance traveled

in meters



Run #1

Run #2

Run #3

Competition racing with group members in the hallway





Who’s car traveled the farthest? ______________________________

Who’s car traveled the fastest in the first 3 meters? ________________

Who’s car exhibited the fastest overall speed? ________________

Part 4  (5 points)


1.Does the length, width and weight of the car make a difference in its performance?  Explain by providing evidence from your races.

2.The key word in this project is friction. Did friction play a role in your races? Explain by providing evidence from your races.

3.  Look-up the word momentum.  Was momentum a factor in your races? Explain your thinking and provide evidence from your data to support your opinion.

The Balloon Car Race!

Rubric: 60 points total!


The car: (up to 20 points)

  • 20 points- The car follows all rules and travels 3 m with fastest speed
  • 19 Points- The car follows all rules and travels 3 m in the 2nd fastest speed
  • 18 Points- The car follows all rules and travels 3 m in the 3rd fastest Speed
  • 17 Points- The car follows all rules and travels 3 m
  • 15 Points- The car follows all rules and travels only 2 m
  • 14 Points- The car does not meet regulations or does not travel 2 m

 The car sketch: (up to 10 points)

  • All details in part 2 are in the sketch and legible
    • -1 point for each missing item from part 2

 The 5 paragraph paper: (up to 20 points)

  • 5 Points: Complete Paragraphs (at least 4 sentences per paragraph): (-1 for each missing paragraph)
  • 5 Points for perfect grammar and spelling (-.25 points for each error up to -3 points)
  • 10 Points did the writer address all questions as described in part 3 (-1 point for each missing question)

 The questions: (5 Points)

  • (-1 for each incomplete answer)

 Cover: ( 5 Points)

  • Name, Date, Class Period, Picture, Packet stapled correctly (-1 for each missing item)