Rubber bands provided the thrust to get your rocket going. Why did the rocket keep moving after it left the launch pad and the rubber bands were no longer pushing it?

The ivanpah solar thermal power plant cost $2.2 billion to build. the gross plant electric output is 392 mw, and the net output is 377 mw. the planned capacity factor was 27.4%, but the actual capacity factor in 2016 was 20.5%. at best the plant thermal efficiency appears to be 18%. in addition, for the daily startup process, the solar plant also burned 1.3x10^12 btu of natural gas in 2016. the cost of natural gas in 2016 was about $2.5 per million btu. assuming a levelized annual fixed charge rate of 7%, determine (a) the capital cost (c/kwh) and (b) the fuel cost (e/k wh) for the electricity in 2016.