Energy+example

Problem 1 Black Board the pirate, mass 85kg, enters the "cave of mystery". The first section of the cave is a short (5m) horizontal section followed by a 100m drop off. The width of the drop off is 20m. On the other side of the drop is a small ledge, the small ledge is 2m lower then the "cave of mystery". As Black board enters the this section of the cave he feels a strong pull from the cave it's self. How much work does this section of the cave have to do on Black Board in order to get him to the other side?