Roller Coaster Physics: Potential Energy and Kinetic Energy Drive the Ride

Every roller coaster is a gravity-powered conversion machine cycling between two energy forms:

Potential Energy (PE)

Stored energy of position. At the lift hill summit, the train has maximum gravitational potential energy: PE = mgh (mass × gravity × height). The chain lift does work against gravity to "charge" this battery. No engines on the train—just this initial investment.

Kinetic Energy (KE)

Energy of motion. As the train descends, PE converts to KE: KE = ½mv². Speed peaks at the bottom. Hills trade KE back to PE (slowing up), then PE to KE (accelerating down). Each cycle loses energy to friction, air resistance, sound, heat—so each hill is lower.

The Energy Budget

• Input: Lift motor work (or launch system: hydraulic, LSM, LIM, compressed air)
• Storage: Gravitational PE at peaks
• Expression: KE as speed, g-forces, airtime
• Losses: Wheel friction (polyurethane on steel), bearing drag, aerodynamic drag, track vibration, brake heat
• Final dissipation: Magnetic / friction brakes convert remaining KE to heat

Launch Coasters: Different Input, Same Physics

Dodonpa, Top Thrill Dragster, Formula Rossa: hydraulic/air/LSM launch imparts massive KE instantly—no lift hill needed. Still obey conservation: KE → PE → KE until brakes.

Two energies. One direction: downhill overall. The thrill is the exchange rate.