We have to choose project in school about the lessons we take. I chose physics, and decided to compose the project about mechanic energy. Actually I purposed to explain the formulas with a simple experiment. In my idea, we leave the ball (enough highness) with no velocity into a big container which fulled with dense fluid. So we can understand the kinetic energy won't continuing to increase because of the friction, and it will be going with fixed velocity. However I thought to increase the potential energy, and keep the ball fixed place for a while. Thus I want to choose the densiest fluid to increase the friction but the ball might burn, and the highness is the big problem. Have you any suggestion about it?