A sled and rider with a combined mass of 103.96 kg are at the top of a hill a height of 158 m above the level ground below. The sled is given a push providing an initial kinetic energy at the top of the hill of 76 J. (a) Choosing a reference level at the bottom of the hill, what is the potential energy of the sled and rider at the top of the hill? (b) After the push, what is the total mechanical energy of the sled and rider at the top of the hill? (c) If friction can be ignored, what will be the kinetic energy of the sled and rider at the bottom of the hill? Use g = 9.8 m/s²