Help! My son has spent countless hours on his high-school physics project, where the challenge is to make a soda can move as far as possible on its own. Nothing can be placed between the can and the floor surface, and nothing can extend beyond the ends of the can by more than 7 mm. Beyond that, anything goes. He is able to get it to move, using rubber bands and batteries taped to the rubber bands, inside the can, but it only moves about 5 feet. He will only get a passing grade on the project if he makes it move at least 10 feet. Any ideas?