i asked to make gravity drive ( vehicle powered by potential energy, which is to travel in an approximately as far as possible). And i need to make the report. But there is part that i cant understand. can someone help me to explain, about analysis of the possible motion of that vehicle ( car) ? thank you :) Solution To be driven by potential energy, the car must move downwards by some distance Consider the bottom half of a circle. If the car starts from Rest at one end, It gains v=(2gR) 1/2 at the bottom of the semi-circle.which is used to move to the other end.So, The car has moved a distance of 2R using potential energy . So, basically the car must go from high to low height in order to drive using potential energy.There must be a part where the car goes to lower height than it initially started with .