The rocket used to launch the 540-kg spacecraft of Problem 14.95 is redesigned to include two stages

Question:

The rocket used to launch the 540-kg spacecraft of Problem 14.95 is redesigned to include two stages A and B, each of mass 9.5 Mg, including 8.9 Mg of fuel. The fuel is again consumed at a rate of 225 kg/s and ejected with a relative velocity of 3600 m/s. Knowing that when stage A expels its last particle of fuel its casing is released and jettisoned, determine (a) the speed of the rocket at that instant, (b) the maximum speed imparted to the spacecraft.