A rocket with an initial mass of 1000 kg adjusts its thrust by varying the rate at which mass is ejected. The ejection speed relative to the rocket is 40 km/s. If the acceleration of the rocket is to have a magnitude of 20 m/s2 at an instant when its mass is 80% of the original mass, at what rate is mass being ejected at that instant? Ignore any external forces on the rocket.
1) 0.40 kg/s
2) 0.50 kg/s
3) 0.60 kg/s
4) 0.70 kg/s
5) 0.80 kg/s
Answer: 1