Engineers are using computer models to study train collisions to design safer train cars. They start by modeling an elastic collision between two train cars
traveling toware each other. Car 1 is traveling east at 6 m/s and has a mass
of 3,154 kg. Car 2 is traveling west at 23 m/s and has a mass of 8,296 kg.
After the collision, car 1 has a final velocity of 7 m/s west. What is the final
velocity of car 2?
A. 23 m/s west
B. 18 m/s west
O C. 23 m/s east
D. 18 m/s east

At a certain instant after jumping from the airplane a, a skydiver b is in the position shown and has reached a terminal (constant) speed vb = 52 m/s. the airplane has the same constant speed va = 52 m/s, and after a period of level flight is just beginning to follow the circular path shown of radius ρa = 2330 m. (a) determine the velocity and acceleration of the airplane relative to the skydiver. (b) determine the time rate of change of the speed vr of the airplane and the radius of curvature ρr of its path, both as observed by the nonrotating skydiver.