In Gerdom v. Gerdom, 444 P.2d 34, 35-36 (Wyo. 1968), the Court determined that the instruction was proper where a jury could determine that a driver pulling a trailer was confronted with a sudden emergency when he hit 1000 feet of ice causing the trailer to begin sliding, and the jury also might have found this condition was unforeseen and without negligence on the part of that driver. 444 P.2d at 36.