I’m posting this again as the other thread is really old and I have more questions about how to build one. This is a project for a high school physics class. Here’s the general instructiona: I need to make a car powered only by gravity/a 1kg mass. The 1 kg mass must fall and power the car. No spring, electrical, chemical, elastic etc power. ONLY GRAVITY. The mass and everything else I use, must travel with the car (although I am creating it so the weight drops off once it falls the distance between the top of the car and the ground.) It must travel 3 meters (32 feet). Right now I have a ca