A recent assignment in our physics class was to create a physics-mobile: a vehicle that would scale a ramp and go down the other side while preventing our classmates from sending their car up the other side. The catch was, we were only allowed to use the following materials:
Two coffee cans w/ plastic lids, eight rubber bands, one 3-foot wooden dowel, any metal fasteners (nails, screws, bolts, etc.), one 12x12 inch piece of plywood, one 12x12 inch sheet of cardboard, four jar lids, four soda bottles, two mouse (not rat) traps, two wire coat hangers, four 4-ounce lead weights, and any glue/modeling cement.
Here are some further details. The ramp is 91.5 cm to the crest, and rises up to a height of 7.62 cm. It is 25.5 cm wide. The car must be no more than 30.5 cm long and 20.5 cm wide at the start of the race. Your car must be self-propelled. You may touch it at the start of the race, but you may not give it a shove. Nothing can be left behind at the starting line. Finally, if both cars or neither car crosses the crest of the hill, there will be a rematch. After three rematches, both cars are disqualified.
My design consisted of two mouse traps glued to the plywood. A wire hanger was epoxyed to the mouse traps to create a giant mouse trap 20.5 cm long. Attached to the hanger were two strings of four rubber bands which wrapped around two coffee can wheels. Once the car was released, the rubber band turned the wheels and sent it zooming up the hill.
This design wound up 4th place in the class, after being defeated by juggernaut cars that were launched like a slingshot bullet by two rubber bands attached to the car. After the race, our teacher decided that those cars were not truly self-propelled, and will rewrite the rules to specifically exclude that style of car.
Your challenge is to dream up a design that is even better than the cars described above. You, too, can be king of the hill/ramp. | 
