During the roller coasters ride through the top of the hill, it begins to gain PE through a machine. It then will beginning ride down the hill causing the gaining of speed. Furthermore, the roller coaster began to gain KE, although it will lose its PE due to losing its height. Kinetic Theory states that the higher the molecules vibrates the higher the temperature, specifically the higher the speed of the roller coaster, the higher the temperature of its wheels cause from friction! Hope this helps
