Rearward tipping seat to prevent whiplash in collisions

A seat comprising a squab (1) and a hack (2) is intended to be mounted in a motor vehicle. The seat is provided with a roller (4) located at the rear part of the squab which engages a rail (5) mounted on the floor of the motor vehicle. The seat may thus be moved forwardly and rearwardly. The seat may pivot rearwardly about the roller (4) in a rear-impact situation. An element (12) provides a resistive force which resists the rearward tipping action, the element (12) being connected between the floor of the vehicle and a rail (7) provided on the vehicle seat. The level of the resistive force is dependent upon the position of the seat, and thus the resistive force is variable in dependence upon a physical characteristic (height) of the occupant of the seat.