Alright. I have a physics project due in about 10 days and im not quite sure how to go about it. I have to make a "vehicle" move as efficiently as possible. I can only use 1 Joule of potentional gravitational energy per the equation mgh. The only specifications of the vehicle are that it is safe to its surrounding and the people watching and that it has at least 2 wheels on the ground at all times. I can either make it move using an inelastic collision (that way the weight of the car isn't counted into mgh) or i can put the car on a ramp and have its vertical height and mass count into the equation. I think that i should just drop the car because not all the work will be conserved into force during an inelastic collision. The simplest way to do it would be a 100g car and the track 1m high. I dont know what the best way to do it is, whith more mass and less hight or the other way around. My idea is to use a maglev type of thing with 2 guidewheels to keep it straight. Any help is much appreciated!