Round Up is an amusement ride

Amusement ride

Amusement rides are large mechanical devices that move people to create enjoyment. They are frequently found at amusement parks, traveling carnivals, and funfairs.-Notable types:*Afterburner*Ali Baba*Balloon Race*Booster...

 consisting of a circular horizontal platform with vertical cage like wall around the edge. The platform is attached to a motor on a hydraulic arm. The ride starts out by spinning until the centrifugal force

Centrifugal force

Centrifugal force can generally be any force directed outward relative to some origin. More particularly, in classical mechanics, the centrifugal force is an outward force which arises when describing the motion of objects in a rotating reference frame...

 is enough to push riders against the wall. At that time, the friction

Friction

Friction is the force resisting the relative motion of solid surfaces, fluid layers, and/or material elements sliding against each other. There are several types of friction:...

 between the riders' backs and the walls is enough to hold them against the wall. Then, the arm raises the horizontal platform to a vertical position in which riders, instead of spinning horizontally, are now spinning vertically.

The ride spins for a predetermined cycle until an automatic timer releases the hydraulic fluid from the arm causing the platform to return to its horizontal position.