Thrill rides, scream machines, loop-de-loops, colossal peaks, and heart-stopping drops—roller coasters may seem to defy all laws of physics, but don’t let that sense of danger fool you. A coaster has potential energy as it is pulled to the top of the highest hill, which changes to kinetic energy as the coaster begins its descent. Once the coaster is underway—gravity, velocity, friction, and acceleration, are just a few of the physics principals controlling the ride. Although coasters are designed to be a frightening experience for passengers, in reality they are safer than crossing the street. Roller coaster designers like Kent Seko create these dynamic rides, which simulate a genuine air of peril.