Example:A rocket whose initial mass is 850 kg consumes fuel at the rate R=2.3 kg/s. The speed u of the exhaust gases relative to the rocket engine is 2800 m/s. (a) What is the initial acceleration of the rocket? (b) Suppose, that the rocket is launched from a spacecraft already in deep space, where we can neglect any gravitational force acting on it. The mass of the rocket when its fuel is exhausted is 180 kg. What is its speed relative to the spacecraft at that time? Assume that the spacecraft is so massive that the launch does not alter its speed.