Physics: Energy

When in the firing position, the counterweight is suspended in the air. This give it potential energy. The arm is at rest as is the sling, which is laying on the ground (our point of reference) meaning it has no potential energy. Once the trigger mechanism is activated, the counter weight drops and the arm and sling begin to move upwards. This is a conversion of the counter weight's potential energy into kinetic energy, which is transferred to the arm and sling. As the sling reaches up, over the trebuchet, both it and the balloon have kinetic energy and gain potential energy. At the top of the arc, the sling begins to lose both potential and kinetic energy as it falls. The balloon comes out of the sling and begins its descent. During this descent, the balloon gains kinetic energy as it converts potential into kinetic. When the balloon strikes the ground, it has converted all of its potential energy into kinetic energy, which it then loses through a transfer to the ground. If we were to move the arm even further down, therefore the counterweight even further up more potential energy would be available to be converted into kinetic energy as the arm swings. This increased amount of kinetic energy would transfer into the balloon, increasing its range.