An 830-kg roller coaster car drops from rest at a height of 93 m along a frictionless track. What is the velocity of the roller coaster at the top of a second hill that is 65 m high? What average force is required to bring the car to a stop along a 110 m stretch of horizontal track at ground level at the end of the ride? Energy _ Energy Initial External Final at hill 1 at hill 2 energy work energy PE PE KE PE O m The velocity of the roller coaster is m/s The average force required is