Roller-Coaster Vocabulary: The Science Behind the Screams
Roller coasters play with the laws of physics to excite and terrify riders—all while staying safe and predictable. Read on to learn more about scream machines and how they work.
Lift hill: the first and tallest incline of a roller coaster. Although an electric motor pulls the cars up, the true energy powering the rest of the journey lies in this peak—a massive source of potential energy. As the cars travel down the hill, the energy becomes kinetic, then potential again, then kinetic—and on and on, always losing momentum on each successively shorter hill.
Inertia: the resistance of an object to any change in motion. Remember Newton’s first law: an object in motion stays in motion. As passengers dive, dip, twist, loop, and corkscrew down the track, they often feel out of control. This is because their inertia—their mass, in other words—is different from that of the cars. At times, the bodies move faster than the coaster and vice versa, making passengers feel like they’re being pushed forward against the restraining bar, pressed back into the seat, or thrown up into the air—a sensation often referred to as air time.
G-force: a force of acceleration, typically measured in units equal to the force exerted by standard gravity. For example, if you were to fall at 2 g’s, you’d be falling twice as fast as normal gravity. G-force can be felt everywhere on a roller coaster, from hills and curves to loop-de-loops. As of 2014, the Tower of Terror in Johannesburg, South Africa, holds the record for the highest g-force: up to 6.3 g’s.
Steel rail: roller coasters made of tubular steel tracks. Less expensive to maintain than wooden roller coasters, these steel-rail rides are also much faster, which comes at a cost: they can’t handle the same tight twists and turns that characterize wooden rides. In 1959, Disneyland introduced the first tubular steel coaster, the Matterhorn Bobsleds, modeled after the Swiss Alps’s massive pile of steel girders.