The culminating task for my physics course was to build a catapult that can launch a ball bearing 2-7m. I built the catapult out of wood and its on a pivot and i'm using a bungee cord to make it snap back when its pulled back. How to I develop a formula to calculate prior to launch how far it can go based on how far is pull back on the bungee cord? what tests should i conduct. I am supposed to be able to develop the formula and the teacher gives me a distance i find out how to calibrate my catapult to hit that distance. I was thinking about just using conservation of energy but i'm not sure about how to go about it since idk the coefficient of elastic nrg for the bungee cord any suggestions?