Roller Coasters, how do they move so fast without any motor pushing them? Energy! More specifically kinetic and potential energy. In the beginning of a roller coaster ride, there is an ascension to the top of hill. The purpose of this is that as the roller coaster gets higher and higher up, it gains potential energy. You could calculate this by doing mass times gravity times height. After the the roller coaster reaches to the top and starts fall down, the potential energy is then transferred in kinetic energy, which moves the roller coaster. Kinetic energy can be calculated by doing one-half times mass times velocity squared. Energy can never be destroyed or created so the the roller coaster has a constant energy total. Therefore kinetic energy can be also transferred to potential energy. This is why roller coasters can move without any motor pushing it.