I was interested in this sign at the fair in Hunstanton. As the ride spins fast, the any object with inertial mass will tend to go in a straight line and will need a centripetal resultant force to pull it round in a circle. The heavier the person, the more force needed. Centripetal force = mass x radius x (angular velocity)^2. All objects wil have the same angular velocity. Putting the biggest mass on the biggest radius will mean a bigger centripetal force required. But more mass further out increases the moment of inertia of the ride which would mean that it will tend to go slower. We wondered whether the practical reason was that the heavier person would have more of a tendency to go straight on and would thus be more likely to crush the person outside them if sat on the inside seat.
