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.")

