Ok so here's the deal. Wind powered machine project.. -Large Industrial Fan blowing -4 meters away from the fan is a wooden block on the ground with a hook in it (to attach rope, etc) -must pull the wooden block 4 meters TOWARDS the fan in the fastest amount of time possible -machine must only be powered by wind. no stored energy, potential energy, etc. -cannot lubricate the floor or put anything under the block -no combustibles/other dangerous thingies :) -to get an A, time must be 2 second or faster So basically need to pull the block 4 meters TOWARDS the fan in the fastest amount of time possible using only the wind power of the fan. I'm thinking I could always use the ol' windmill technique but I'd rather do something different. Any ideas?