A 1000-kg rocket has a net propulsion force of 20 kN (kiloNewtons). Over a short time period, it uniformly speeds up from an initial velocity of 30 m/s to a final velocity of 60 m/s. Assume that the mass of the rocket is constant during this time period and that the net force is along the direction of motion. What is the net work done on the rocket in kilojoules (kJ)?