Consider a railroad flat car of weight W=2760 N that can roll without friction along a straight horizontal track. Initially a man of weight w=496 N is simply standing on the car, which is moving to the right with speed Vo=3.8km/hr. What is the change in speed of the car (in km/hr, ) if the man runs to the left so that his speed relative to the car is Vrel=13.8km/hr?