Given a chain weighing 2 pounds per foot, with a 150 pound weight attached to the end. The weighted end of the chain starts at an initial position 10 feet below a ledge on a 100 foot building. It is lowered to 10 feet above the ground. Calculate the work done by gravity (ignoring all other forces).
Since the building is 100 feet, and the end of the is initially hanging 10 feet over the building edge, it is starts at a position 90 feet above the ground. It is lowered to 10 feet above the ground. The force of gravity acting on the chain is , so the work done is