Aroller coaster (378 kg) moves from a (3.24 m above the ground) to b (28.3 m above the ground). two non-conservative forces are present: friction does -2.84 x 104 j of work on the car, and a chain mechanism does +5.24 x 104 j of work to the car up a long climb. what is the change in the car's kinetic energy kef - keo from a to b?