a)A rocket takes off from from a space station, where there is no gravity other than the negligible gravity due to the space station at speed of 125 m/s. If the exhaust speed is 1500 m/s and the mass of fuel burned is 81 kg, what was the initial mass (in kg) of the rocket?

b)What exhaust speed in km/s is required to accelerate a rocket in deep space from 800 m/s to 1000 m/s in 5.0 s if the total rocket mass is 1200 kg and the rocket only has 50 kg of fuel left? Give your answers to two significant figures without units.