two trains are moving in opposite directions. train A moves east with a speed of 72km/hr and train B moves west with a speed of 90km/hr. (1) what is the relative velocity of b with respect to A. (2) what is the relative velocity of ground with respect to B. (3) what is the velocity of the dog runnin g on the roof of the train A against its motion( with velocity of 54km/hr with respect to train A) as observed by a man on the ground.
