The train consists of a 30-Mg engine E, and cars A, B, and C, which have a mass of 15 Mg,...

The train consists of a 30-Mg engine E, and cars A, B, and C, which have a mass of 15 Mg, 10 Mg, and 8 Mg, respectively. If the tracks provide a traction force of F = 30 kN on the engine wheels, determine the speed of the train when t = 30 s, starting from rest. Also, find the horizontal coupling force at D between the engine E and car A. Neglect rolling resistance.