Avan is traveling at a speed of 55 km/h. a girl sitting near the driver of the van throws a paper airplane to a boy at the back of the van with a speed of 2 km/h. the speed of the paper airplane, to the nearest whole number relative to the boy, is (blank) km/h.

Complete these sentences. if a roller coaster train has a potential energy of 1,500 j and a kinetic energy of 500 j as it starts to travel downhill, its total energy isj. once the roller coaster train gets closer to the bottom of the hill, its kinetic energy increases to 1,100 j, and its potential energy decreases to j. when the train reaches the bottom of the track and is traveling along the ground, its kinetic energy isj.