the catapult that my group built was somewhat of a success, thanks to physics. when we pulled the trigger, our weights were pulled towards the earth at a rate of 9m/s^2. when this happened, it exerted a force on the arm of the catapult which rotated around the pipe. the force of the weights on the arm was exactly the same as the force of the arm on the weights as newtons 3rd law states. when the other end of the arm reaches about 45 degrees, it lets go of the softball which was traveling at around 7m/s. the project was really fun but it also taught me about how much physics is involved with everyday life.