Science Buddies: "Ask an Expert"

I built a cannon that uses the pressure from sublimation of dry ice to propel a tennis ball. The cannon was built from PVC pipe, etc., according to advice from Make magazine. The pressure is held in the pressure container using a disc of aluminum foil; when the foil disc bursts, the ball is shot out the barrel. For my experiment, I compared a single layer of foil to a double layer of foil. I measured the pressure that built up in the pressure container, and I measured the distance that the ball went before it landed. I did five trials for each condition.

I wonder what category is best for this project? I was thinking that it might go in Eng: Materials & Bioengineering, because it concerns the material used for the burst disc. Other ideas: Energy & Transportation (since the tennis ball is "transported"). Physics and Astronomy (since the physical forces that propel the ball are important). What category would be best?

Another question: I know that ISEF projects can be judged as Science Projects or as Engineering Projects. <http://student.societyforscience.org/ju ... ef?pid=284> As I understand it, the Science projects involve dependent and independent variables, while the Engineering Projects are meant to solve a practical problem rather than test a variable. Can a project in an Engineering category be judged as a Science project because it tests a variable (burst disc made of a single or double layer of foil)? Or are all Engineering projects juged by how well they solve a practical problem (how to shoot a projectile farthest, using dry ice as a propellant)? Which would be best for this project?

Thanks! (Note: I also posted this under "Grades 9-12: Physical Science.")

Hi LaureenMT,

The choice about which category to go in is up to you in the end. But, here are my thoughts on the matter. I don't think Energy and Transportation is a good fit. If you are primarily concerned with improving the design or performance of the dry ice cannon, then I suggest entering as an engineering project in an engineering category. I probably wouldn't choose materials and bioengineering but rather electrical and mechanical engineering. If you are primarily focused on the physics of the problem (e.g., how far the ball goes as a function of pressure, etc.), then physics and astronomy may be the better option.

I suspect you've already read this, but here is the Intel ISEF's guidance on selecting a category:
https://student.societyforscience.org/i ... egories#EE

As far as being judged as an engineering or science experiment project, let me first say that I have only judged at regional fairs, not the actual Intel ISEF. However, I suspect the judges will decide for themselves how to best evaluate your project. That being said, if you enter in an engineering category, it is much more likely you will be evaluated according to the engineering criteria.

Terik, I agree with your analysis. Somehow, I had not seen the Mechanical and Electrical Engineering category on the list, but it is clearly the best fit. And using the engineering criteria for judging probably makes sense as well. Thank you for taking the time to respond.