I am wondering how this all works and am hoping to get some guidance. If a 1000 lb weight freefalls vertically from 660 ft the energy is 894,289 joules. If the fall is down a 30 degree slope that is 1300 ft long, then it takes 17 seconds and the potential energy can be said to be 53 KW. If, and I really mean if, I did that math right then my question has to do with converting that 53KW into kinetic energy. If the 1000 lb. weight is brought to a stop by a mechanical device, rather than impacting the earth, does the 53KW transfer to the mechanical device? If so does all or most of it transfer? Secondly, if the mechanical device takes longer than the 17 seconds of freefall to bring the weight to a stop is the 53KW of potential energy still available? My guess is that no matter how long the mechanical device takes to bring the weight to a stop the potential energy, of 53KW, would remain the same.