Procedure:
Create 40 2.5-lb. bags of sand to be added to the counterweight. Take the trebuchet to a level area free from overhead obstruction. Put the basketball in the sling and pull the arm down to where it touches the ground. Slip the free end of the sling over the firing pin and release the arm. Time the flight of the ball from the point where it passes through the plane of the trebuchet perpendicular to the ground passing through the pivot rod until it hits the ground. Measure from the base of the trebuchet to the point where the basketball first touches the ground. Repeat the firing and recording of the trebuchet for a total of three firings. Add four of the bags of sand to the counterweight bucket, raising the weight by ten lbs. Repeat the firing and recording of the trebuchet, adding ten lbs. every three trials until the trebuchet has been fired three times with 100 lbs. added to the counterweight. Dismantle the trebuchet and remove 1 foot from the end of the arm, keeping the braces 6 inches from the end. Repeat the firing and recording of the trebuchet, removing another 1-foot section when you reach the third trial at 100 lbs. until the trebuchet has fired three times at 100 lbs. with an arm length of 10 feet. Return the trebuchet to its storage space.