Hi, I have to do a high school project in physics regarding to build a catapult. The catapult must launch a tennis ball 12 meters from the launch line into the trash can. My friends and I are confused on what materials to use in this project and how to exactly make it so it can fit the requirements of this project ? What exactly is the most important factor in this project to let this catapult launch 12 meters away? Can you help me?