An impact-G-force, vector-modifying seat structure in a vehicle, which seat structure introduces, in a forward crash situation, and in a generally vertical plane, a special forward, then upward, and then rearward rotation of the base of the spine of a seated occupant. This motion tends to minimize crash injuries.

A roller coaster ride includes a pair of spaced apart parallel tracks and a car assembly. The car assembly includes a superstructure with wheels which engage the track and a passenger compartment which is coupled to the superstructure but force-isolated from it by force controlling devices. According to the presently preferred embodiment, the force controlling devices include springs and pneumatic cylinders. The pneumatic cylinders are preferably controlled by an electrically operated pump/valve in response to signals from the roller coaster operator and/or a computer. The passenger compartment is preferably provided with a plurality of sensors for sensing velocity and acceleration as well as the condition of doors and restraints. According to one embodiment of the invention, the outputs from sensors are transmitted to the roller coaster operator and the operator manually activates pumps/valves to alter the forces acting on the passenger compartment. According to a second embodiment, the outputs from sensors are transmitted to a central computer which sends signals to the pumps/valves in response to a program which responds to the sensor signals. According to a third embodiment, the outputs from sensors are transmitted to an onboard computer which sends signals to the pumps/valves in response to a program which responds to the sensor signals.