Murphy v. Steeplechase

When should courts presume that a plaintiff has sufficient knowledge to have "assumed the risk"? The plaintiff suffered a fractured of a knee cap while "riding" an attraction maintained by the defendant, known as 'the Flopper'. The injury was caused by the plaintiff tumbling off of the ride; however, as the name implies, the attraction was made to challenge the balance of riders and throw them onto padded walls or flooring. Furthermore, the plaintiff witnessed other riders falling off of the Flopper before he himself stepped on.