Three identical train cars, coupled together, are rolling east at speed vo. A fourth car traveling east at 2uo catches up with the three and couples to make a four-car train. A moment later, the train cars hit a fifth car that was at rest on the tracks, and it couples to make a five-car train. Part A What is the speed of the five-car train? Express your answer in terms of up. View Available Hint(s) VO ΑΣΦ ? U5 = Submit