) A sled and rider with combined mass of 65 kg are perched at the top of a hill. The top of this hill is 50 m above level ground below. A second bump in the hill 35 m above the ground. Suppose that we also know that approximately 4500 J of work is done against friction as the sled travels between these two points. (a) Choosing ground as a reference level, what is the potential energy of sled and rider at the top of first hill? (b) What is the Potential energy of sled and rider at top of second peak? (c)Will the sled make it to the top of the second bump if no kinetic energy is given to sled at the start of its motion? Explain. d) If friction is ignored, what will be the Kinetic energy and speed of the sled and rider at the bottom of hill (point C)?