The+Physics+of+a+Catapult

 The physics of a catapult is the physics of rotational motion. The arm of the catapult rotates around an axis, which provides the movement needed to throw a projectile. The force that causes this movement is known as torque. It is the force applied to the arm through the material applying tension to the arm, in the case of our catapult bungee cords. This torque causes the arm to accelerate, and gain momentum along with angular velocity. Some of this velocity and momentum is transferred to the projectile when it is launched, giving it linear momentum and allowing it to travel as far as possible. Some of the energy stored in the tension material is lost because of the design of a catapult. The trick is to find the proper length of the arm and tension giving material, along with the best launch angle, so as to minimize the amount of energy lost in the launch. The physics of our catapult specifically is very simple. Our tension giving material (bungee chords) is stretched from the front of out catapult to the arm, over the bar that allows for a proper launch angle. The potential energy stored in the bungee chords is at a maximum when the arm is pulled all the way to its farthest angle away from the launching bar. When released, the bungee chords sling the arm forward as it rotates on a dowel. The arm hits the launching bar, causing all the energy transferred from the chords to the arm to be transferred into the tennis ball. The tennis ball is then hurled forward, and can reach a distance of about twenty-five and a half feet, or 8.5 yards.