This roller coaster’s track is nearly frictionless, so resistance can be ignored. using g = 9.8 m/s2, what best describes the roller coaster car when it is at the top of the loop-de-loop? the car has only potential energy, so it is moving at 0 m/s. the car has both potential and kinetic energy, and it is moving at 24.6 m/s. the car has both potential and kinetic energy, and it is moving at 34.9 m/s. the car’s potential energy has all been converted to kinetic energy, so it moves at 42.7 m/s.