[jeff5may]

I'm not a physics professor, but I believe the difference here lies between watts and watt hours. In Zwerius' above example, both solitions require 90 watt hours of work. IIRC, the time does not factor in as to the raw amount of work demanded. The supply side is a different story: most jobs are accomplished faster with a less efficient engine. Think corvair versus corvette. Same work performed, corvette gets there faster but uses more fuel.

This same set of misconceptions is manipulated by the "free energy / over unity power gain" folks. A common example is the flywheel: with a really slick set of bearings, friction is very low. As long as you are adding energy to spin the flywheel, it will spin faster and faster. It will coast for a very, very long time if left alone. Many inventions can be rigged to the wheel to do no work but appear to go something special. But once you try to draw a load from the flywheel, it slows down. TANSTAAFL.