A50-mg boxcar a is moving in a railroad switchyard with a velocity of 10 km/h toward cars b and c, which are both at rest with their brakes off at a short distance from each other. car b is a 25-mg flatcar supporting a 40-mg container, and car c is a 45-mg boxcar. as the cars hit each other, they get automatically and tightly coupled. determine the velocity of car a immediately after each of the two couplings, assuming that the container does not slide on the flatcar.