Balloon Cars Revisited: Alternative Fuel Gases

This activity is an extension of the commonly used balloon car activity. This activity is designed for students to use a variety of skills including critical thinking, questioning, and developing of a working model to create the cars in the first part of this activity. In addition, the use of different gases as a fuel source is intended to have the students use data analysis and critical thinking to explain the results.

The alternative fuel sources part of the activity is a one day activity which will be added onto the car creation component. The total time devoted to both parts of this activity is 5 class periods: 3 for the construction of the cars, 1 to race the cars with only air, and 1 to implement the alternative fuel portion. This additional exploration of fuel sources is intended to a chemistry component into the physics component of the project.

The introduction of this activity takes most of a class period as rules, safety, materials, requirements, groups, assessments, etc. are explained. The students use the rest of this day in their groups to draw out and plan their cars. On day two, they can't start construction of their cars until I sign off on their plan (this doesn't mean they can't change their ideas, but it helps with the conservation of materials). The student groups can pick one of two classes of cars to create, either a stock class or modified class. The stock cars can only be made from the materials I provide for them, while the modified cars can use materials from outside the classroom. However, all cars must operate with the balloon motor setup I provide for them. The students are given two full class periods to create and test their new cars. If desired they are allowed to work in the shop, art room, or at home. The beginning of day three starts with a car show, where each class stock and modified compete in the best of show car show. (I use this as a means of making sure all groups have a completed car on time) The best looking car, as voted by their classmates, receive a prize. We then go to the gym and run distance trial races for the cars. Each group participates in a set number of trial runs of their can completing a data table of the distances the car traveled. at the end of this day they are assigned to add an essay to their data sheet that includes what they could do to improve the car and to explain how this car relates to Newton's Laws. At the beginning of the final day, they are allowed 15 minutes to make any modifications they want to the cars. We return to the gym and conduct distance trials again using three separate fuel sources: air, helium, and carbon dioxide. They record this information into a data table and are to answer the following questions: 1.Did all of the fuels cause the cars to travel the same distance? 2.Which of the fuels caused the car to travel the longest distance? 3.Why do you think that the fuel that caused your car to travel the longest distance did so? 4.What do you think would happen if we had also used nitrogen gas and oxygen gas to fuel the cars? Following this activity, we wrap up by discussing the results, how this relates to Newton's Laws, and how this relates to the idea that at the same temperature the gas with the smaller molecular mass travels faster and thus leaves the balloon at a faster rate and should push the car a further distance.

1. You need an almost endless supply of balloons
2. I used to use plastic milk tops as wheels, but I now use a collection of plastic wheels from my kids toys.
3. Small diameter skewer sticks inside straws work well as axles.

1. creation of the car
2. the car actually moves
3. the data table and Newton Law essay
4. the alternative fuel source data table and questions
***The alternate fuel sources on the second day of racing is what has been added to what I have done in the past. (The biggest question I have at this point is how it is going to go trying to fill balloons with the other gases.)

2009 Minnesota Science standards
8.1.1.2.1 science 9-12
9C.2.1.2.4 chemistry